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ltc5598 1 5598f typical application description 5mhz to 1600mhz high linearity direct quadrature modulator the ltc ? 5598 is a direct i/q modulator designed for high performance wireless applications, including wireless infrastructure. it allows direct modulation of an rf signal using differential baseband i and q signals. it supports point-to-point microwave link, gsm, edge, cdma, 700mhz band lte, cdma2000, catv applications and other systems. it may also be con? gured as an image reject upconverting mixer, by applying 90 phase-shifted signals to the i and q inputs. the i/q baseband inputs consist of voltage-to-current converters that in turn drive double-balanced mixers. the outputs of these mixers are summed and applied to a buffer, which converts the differential mixer signals to a 50 single-ended buffered rf output. the four balanced i and q baseband input ports are intended for dc coupling from a source with a common-mode voltage level of about 0.5v. the lo path consists of an lo buffer with single-ended or differential inputs, and precision quadrature generators that produce the lo drive for the mixers. the supply voltage range is 4.5v to 5.25v, with about 168ma current. 5mhz to 1600mhz direct conversion transmitter application l , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. features applications n frequency range: 5mhz to 1600mhz n high output ip3: +27.7dbm at 140mhz +22.9dbm at 900mhz n low output noise floor at 6mhz offset: no baseband ac input: C161.2dbm/hz p out = 5.5dbm: C160dbm/hz n low lo feedthrough: C55dbm at 140mhz n high image rejection: C50.4dbc at 140mhz n integrated lo buffer and lo quadrature phase generator n 50 single-ended lo and rf ports n >400mhz baseband bandwidth n 24-lead qfn 4mm 4mm package n pin-compatible with industry standard pin-out n shut-down mode n point-to-point microwave link n military radio n basestation transmitter gsm/edge/cdma2k n 700mhz lte basestation transmitter n satellite communication n catv/cable broadband modulator n 13.56mhz/uhf rfid modulator 90 o 0 o ltc5598 10nf 50 10nf 470nf 10nf baseband generator pa rf = 5mhz to 1600mhz 1nf x2 4.7f x2 en 5v v-i v-i i-channel q-channel v cc 5598 ta01 i-dac q-dac vco/synthesizer rf output power (dbm) noise floor at 6mhz offset (dbm/hz) C152 C154 C156 C158 C160 C162 5598 ta02 8 246 C4 C2 0 C12 C10 C8 C6 C14 f lo = 140mhz; f bb = 2khz; cw (note 3) 20dbm 19.3dbm 13.4dbm 10.4dbm 8.4dbm 6.4dbm noise floor vs rf output power and differential lo input power
ltc5598 2 5598f pin configuration absolute maximum ratings supply voltage .........................................................5.6v common mode level of bbpi, bbmi and bbpq, bbmq ...........................................................0.6v lop, lom input ....................................................20dbm voltage on any pin not to exceed ...................................?0.3v to v cc + 0.3v t jmax .................................................................... 150c operating temperature range..................? 40c to 85c storage temperature range ...................?65c to 150c (note 1) 24 23 22 21 20 19 7 8 9 top view uf package 24-lead (4mm s 4mm) plastic qfn 10 11 12 6 5 4 3 25 2 1 13 14 15 16 17 18 en gnd lop lom gnd capa v cc2 gndrf rf nc gndrf nc v cc1 gnd bbmi bbpi gnd gnd capb gnd bbmq bbpq gnd gnd t jmax = 150c, ja = 37c/w exposed pad (pin 25) is gnd, must be soldered to pcb order information lead free finish tape and reel part marking package description temperature range LTC5598IUF#pbf LTC5598IUF#trpbf 5598 24-lead (4mm 4mm) plastic qfn ?40c to 85c consult ltc marketing for parts speci? ed with wider operating temperature ranges. consult ltc marketing for information on non-standard lead based ? nish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel speci? cations, go to: http://www.linear.com/tapeandreel/
ltc5598 3 5598f symbol parameter conditions min typ max units rf output (rf) f rf rf frequency range 5 to 1600 mhz s 22, on rf output return loss en = high, 5mhz to 1600mhz < C20 db f lo = 140mhz, f rf = 139.9mhz g v conversion voltage gain 20 ? log (v rf, out, 50 /v in, diff, i or q )C2db p out absolute output power 1v pp,diff on each i&q inputs 2 dbm op1db output 1db compression 8.5 dbm oip2 output 2nd order intercept (notes 4, 5) 74 dbm oip3 output 3rd order intercept (notes 4, 6) 27.7 dbm nfloor rf output noise floor no baseband ac input signal (note 3) p out = 4.6dbm (note 3) p lo, se = 10dbm p out = 5.5dbm (note 3) p lo, diff = 20dbm C161.2 C154.5 C160 dbm/hz dbm/hz dbm/hz ir image rejection (note 7) C50.4 dbc loft lo feedthrough (carrier leakage) en = high (note 7) en = low (note 7) C55 C78 dbm dbm f lo = 450mhz, f rf = 449.9mhz g v conversion voltage gain 20 ? log (v rf, out, 50 /v in, diff, i or q ) C5.0 C2.1 0.5 db p out absolute output power 1v pp,diff on each i&q inputs 1.9 dbm op1db output 1db compression 8.4 dbm oip2 output 2nd order intercept (notes 4, 5) 72 dbm oip3 output 3rd order intercept (notes 4, 6) 25.5 dbm nfloor rf output noise floor no baseband ac input signal (note 3) C160.9 dbm/hz ir image rejection (note 7) C55 dbc loft lo feedthrough (carrier leakage) en = high (note 7) en = low (note 7) C51 C68 dbm dbm f lo = 900mhz, f rf = 899.9mhz g v conversion voltage gain 20 ? log (v rf, out, 50 /v in, diff, i or q )C2db p out absolute output power 1v pp,diff on each i&q inputs 2 dbm op1db output 1db compression 8.5 dbm oip2 output 2nd order intercept (notes 4, 5) 69 dbm oip3 output 3rd order intercept (notes 4, 6) 22.9 dbm nfloor rf output noise floor no baseband ac input signal (note 3) p out = 5.2dbm (note 3) p lo, se = 10dbm C160.3 C154.5 dbm/hz dbm/hz ir image rejection (note 7) C54 dbc loft lo feedthrough (carrier leakage) en = high (note 7) en = low (note 7) C48 C54 dbm dbm electrical characteristics v cc = 5v, en = 5v, t a = 25oc, p lo = 0dbm, single-ended; bbpi, bbmi, bbpq, bbmq common-mode dc voltage v cmbb = 0.5v dc , i&q baseband input signal = 100khz cw, 0.8v pp,diff each, i&q 90 shifted (lower side-band selection), unless otherwise noted. (note 11)
ltc5598 4 5598f electrical characteristics v cc = 5v, en = 5v, t a = 25oc, p lo = 0dbm, single-ended; bbpi, bbmi, bbpq, bbmq common-mode dc voltage v cmbb = 0.5v dc , i&q baseband input signal = 100khz cw, 0.8v pp,diff each, i&q 90 shifted (lower side-band selection), unless otherwise noted. (note 11) symbol parameter conditions min typ max units lo input (lop) f lo lo frequency range 5 to 1600 mhz p lo,diff differential lo input power range C10 to 20 dbm p lo, se single-ended lo input power range C10 to 12 dbm s 11, on lo input return loss en = high C10.5 db s 11, off lo input return loss en = low C9.6 db baseband inputs (bbpi, bbmi, bbpq, bbmq) bw bb baseband bandwidth -3db bandwidth >400 mhz i b,bb baseband input current single-ended C 68 a r in, se input resistance single-ended C7.4 k v cmbb dc common-mode voltage externally applied 0.5 v v swing amplitude swing no hard clipping, single-ended 0.86 v p-p power supply (v cc1 , v cc2 ) v cc supply voltage 4.5 5 5.25 v i cc(on) supply current en = high, i cc1 + i cc2 130 165 200 ma i cc(off) supply current, sleep mode en = 0v, i cc1 + i cc2 0.24 0.9 ma t on turn-on time en = low to high (notes 8, 10) 75 ns t off turn-off time en = high to low (notes 9, 10) 10 ns power up/down enable input high voltage input high current en = high en = 5v 2 43 v a sleep input low voltage input low current en = low en = 0v C40 1v a note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: the ltc5598 is guaranteed functional over the operating temperature range C40oc to 85oc. note 3: at 6mhz offset from the lo signal frequency. 100nf between bbpi and bbmi, 100nf between bbpq and bbmq. note 4: baseband is driven by 2mhz and 2.1mhz tones with 1v pp,diff for two-tone signals at each i or q input (0.5v pp,diff for each tone). note 5: im2 is measured at lo frequency C 4.1mhz. note 6: im3 is measured at lo frequency C 1.9 mhz and lo frequency C 2.2mhz. note 7: amplitude average of the characterization data set without image or lo feedthrough nulling (unadjusted). note 8: rf power is within 10% of ? nal value. note 9: rf power is at least 30db lower than in the on state. note 10: external coupling capacitors at pins lop , lom and rf are 100pf each. note 11: tests are performed as shown in the con? guration of figure 10. the lo power is applied to j3 while j5 is terminated with 50 to ground for single-ended lo drive.
ltc5598 5 5598f typical performance characteristics temperature (c) C40 140 supply current (ma) 170 160 150 180 85 C15 10 35 5598 g01 60 5.25v 5.0v 4.5v output ip2 vs rf frequency output 1db compression vs rf frequency lo feedthrough to rf output vs lo frequency image rejection vs lo frequency noise floor vs rf frequency (no ac baseband input signal) supply current vs temperature voltage gain vs rf frequency output ip3 vs rf frequency v cc = 5v, en = 5v, t a = 25oc, f rf = f lo C f bb , p lo = 0dbm single-ended, bbpi, bbmi, bbpq, bbmq common-mode dc voltage v cmbb = 0.5v dc , i&q baseband input signal = 100khz, 0.8v pp,diff , two-tone baseband input signal = 2mhz, 2.1mhz, 0.5v pp,diff each tone, i&q 90 shifted (lower side-band selection); f noise = f lo C 6mhz; unless otherwise noted. (note 11) rf two-tone power (each tone), im2 and im3 vs rf frequency rf frequency (mhz) voltage gain (db) C1 C3 C2 C4 C5 1000 5598 g02 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) oip3 (dbm) 29 21 23 27 25 19 17 1000 5598 g03 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) oip2 (dbm) 85 70 75 80 65 60 55 5598 g04 100 1000 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) op1db (dbm) 10 6 8 4 2 0 5598 g05 100 1000 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c lo frequency (mhz) lo feedthrough (dbm) C40 C50 C60 C70 5598 g06 100 1000 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c lo frequency (mhz) image rejection (dbc) C20 C30 C40 C50 C60 C70 5598 g07 100 1000 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) noise floor (dbm/hz) C145 C155 C150 C160 C165 5598 g08 100 1000 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c (note 3) rf frequency (mhz) p rf,tone (dbm) im2 (dbm), im3 (dbm) 0 C50 C40 C30 C20 C10 C60 C40 C90 C80 C70 C60 C50 C100 5598 g09 1000 100 10 f rf, each = f lo C f bb1 f im3 = f lo + 2*f bb1 +f bb2 f im3 = f lo C 2*f bb1 +f bb2 f im2 = f lo C f bb1 Cf bb2
ltc5598 6 5598f lo feedthrough to rf output vs lo frequency (p lo = 10dbm) image rejection vs lo frequency (p lo = 10dbm) rf two-tone power (each tone), im2 and im3 vs rf frequency (p lo = 10dbm) output ip3 vs rf frequency (p lo = 10dbm) output ip2 vs rf frequency (p lo = 10dbm) output 1db compression vs rf frequency (p lo = 10dbm) typical performance characteristics v cc = 5v, en = 5v, t a = 25oc, f rf = f lo C f bb , p lo = 0dbm single-ended, bbpi, bbmi, bbpq, bbmq common-mode dc voltage v cmbb = 0.5v dc , i&q baseband input signal = 100khz, 0.8v pp,diff , two-tone baseband input signal = 2mhz, 2.1mhz, 0.5v pp,diff each tone, i&q 90 shifted (lower side-band selection); f noise = f lo C 6mhz; unless otherwise noted. (note 11) voltage gain vs rf frequency (p lo = 10dbm) rf two-tone power (each tone), im2 and im3 vs baseband voltage and temperature (f lo = 140mhz) rf two-tone power (each tone), im2 and im3 vs baseband voltage and temperature (f lo = 900mhz) f rf, each = f lo Cf bb1 f im3 = f lo C 2*f bb1 +f bb2 f im3 = f lo + 2*f bb1 +f bb2 f im2 = f lo C f bb1 Cf bb2 i and q baseband voltage (v pp , diff, each tone ) 0.1 p rf, tone (dbm) 10 C40 C30 C20 C10 0 C50 C30 C80 C70 C60 C50 C40 C90 5598 g10 1 im2 (dbm), im3 (dbm) i and q baseband voltage (v pp , diff, each tone ) 0.1 p rf,tone (dbm) im2 (dbm), im3 (dbm) 10 C40 C30 C20 C10 0 C50 C30 C80 C70 C60 C50 C40 C90 5598 g11 1 f rf, each = f lo C f bb1 f im3 = f lo + 2*f bb1 +f bb2 f im3 = f lo C 2*f bb1 +f bb2 f im2 = f lo C f bb1 Cf bb2 rf frequency (mhz) voltage gain (db) C1 C4 C3 C2 C5 5598 g12 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c p lo = 10dbm rf frequency (mhz) oip3 (dbm) 29 25 23 21 19 27 17 5598 g13 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) oip2 (dbm) 85 75 70 65 60 80 55 5598 g14 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) op1db (dbm) 10 8 6 4 2 0 5598 g15 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c lo frequency (mhz) lo feedthrough (dbm) C40 C50 C60 C70 5598 g16 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c lo frequency (mhz) image rejection (dbc) C20 C30 C40 C50 C60 C70 5598 g17 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c rf frequency (mhz) p rf, tone (dbm) im2 (dbm), im3 (dbm) 0 C60 C40 C100 5598 g18 1000 100 10 f rf, each = f lo C f bb1 f im3 = f lo C 2*f bb1 +f bb2 f im3 = f lo + 2*f bb1 +f bb2 f im2 = f lo C f bb1 Cf bb2
ltc5598 7 5598f noise floor vs rf frequency (p lo = 10dbm, no ac baseband input signal) image rejection distribution lo feedthrough distribution gain distribution lo feedthrough to rf output vs lo frequency for en = low output ip3 distribution at 25c typical performance characteristics v cc = 5v, en = 5v, t a = 25oc, f rf = f lo C f bb , f lo = 450mhz, p lo = 0dbm single-ended, bbpi, bbmi, bbpq, bbmq common-mode dc voltage v cmbb = 0.5v dc , i&q baseband input signal = 100khz, 0.8v pp,diff , two-tone baseband input signal = 2mhz, 2.1mhz, 0.5v pp,diff each tone, i&q 90 shifted (lower side-band selection); f noise = f lo C 6mhz; unless otherwise noted. (note 11) rf frequency (mhz) noise floor (dbm/hz) C145 C150 C155 C160 C165 5598 g19 1000 100 10 5v, 25c 5.25v, 25c 4.5v, 25c 5v, C40c 5v, 85c (note 3) lo frequency (mhz) lo feedthrough (dbm) C40 C80 C60 C100 C120 C140 5598 g20 1000 100 10 p lo = 10dbm p lo = 0dbm C40c 85c gain (db) percentage (%) 60 50 40 30 20 10 0 5598 g21 C1.9 C2 C2.2 C2.1 C2.3 C2.4 85 o c 25 o c C40 o c oip3 (dbm) percentage (%) 30 25 20 10 15 5 0 5598 g22 26.8 27.2 25.6 26 26.4 24.8 25.2 24.4 24 lo feedthrough (dbm) percentage (%) 25 20 15 10 5 0 5598 g23 C42 C38 C54 C50 C46 C62 C58 C66 C70 85 o c 25 o c C40 o c image rejection (dbc) percentage (%) 40 35 30 20 25 15 10 5 0 5598 g24 C42 C46 C62 C58 C54 C50 C66 C70 85 o c 25 o c C40 o c noise floor (dbm/hz) percentage (%) 70 60 50 20 40 30 10 0 5598 g25 C160.4 C160 C161.2 C160.8 C161.6 C162 C162.4 85 o c 25 o c C40 o c no rf noise floor distribution lo frequency (mhz) image rejection (dbc) 0 C80 C70 C60 C50 C40 C30 C20 C10 5598 g20a 1000 100 10 c8 = 0 c8 = 470nf image rejection vs lo frequency (p lo = 10dbm) rf output power (dbm) noise floor at 6mhz offset (dbm/hz) C152 C154 C156 C160 C158 C162 5598 g20b 8 6 4 2 0 C2 C4 C6 C8 C10 C12 C14 20dbm 19.3dbm 13.4dbm 10.4dbm 8.4dbm 6.4dbm f lo = 140mhz; f bb = 2khz; cw (note 3) noise floor vs rf output power and differential lo input power
ltc5598 8 5598f block diagram pin functions en (pin 1): enable input. when the enable pin voltage is higher than 2 v, the ic is turned on. when the input voltage is less than 1 v, the ic is turned off. if not connected, the ic is enabled. gnd (pins 2, 5, 8, 11, 12, 19, 20, 23 and 25): ground. pins 2, 5, 8, 11, 12, 19, 20, 23 and exposed pad 25 are connected to each other internally. for best rf performance, pins 2, 5, 8, 11, 12, 19, 20, 23 and the exposed pad 25 should be connected to rf ground. lop (pin 3): positive lo input. this lo input is internally biased at about 2.3v. an ac de-coupling capacitor should be used at this pin to match to an external 50 source. lom (pin 4): negative lo input. this input is internally biased at about 2.3v. an ac de-coupling capacitor should be used at this pin via a 50 to ground for best oip2 performance. capa, capb (pins 6, 7): external capacitor pins. a cap- acitor between the capa and the capb pin can be used in order to improve the image rejection for frequencies below 100mhz. a capacitor value of 470nf is recommended. these pins are internally biased at about 2.3v. bbmq, bbpq (pins 9, 10): baseband inputs for the q-channel, each high input impedance. they should be externally biased at 0.5v common-mode level and not be left ? oating. applied common-mode voltage must stay below 0.6v dc . nc (pins 13, 15): no connect. these pins are ? oating. gndrf (pins 14, 17): ground. pins 14 and 17 are connected to each other internally and function as the ground return for the rf output buffer. they are connected via back-to-back diodes to the exposed pad 25. for best lo suppression performance those pins should be grounded separately from the exposed paddle 25. for best rf performance, pins 14 and 17 should be connected to rf ground. rf (pin 16): rf output. the rf output is a dc-coupled single-ended output with approximately 50 output impedance at rf frequencies. an ac coupling capacitor should be used at this pin to connect to an external load. v cc (pins 18, 24): power supply. it is recommended to use 1nf and 4.7f capacitors for decoupling to ground on each of these pins. bbpi, bbmi (pins 21, 22): baseband inputs for the q- channel, each high input impedance. they should be externally biased at 0.5v common-mode level and not be left ? oating. applied common-mode voltage must stay below 0.6v dc . exposed pad (pin 25): ground. this pin must be soldered to the printed circuit board ground plane. 90 o 0 o ltc5598 v-i v-i rf gndrf lop lom capa capb 16 en 1 3 11 8 gnd 5 2 9 10 22 21 24 18 nc 13 15 bbpi bbmi bbpq bbmq 25 23 20 gnd 7 6 4 5598 bd 19 17 gnd 14 12 v cc1 v cc2
ltc5598 9 5598f the ltc5598 consists of i and q input differential voltage- to-current converters, i and q up-conversion mixers, an rf output buffer, an lo quadrature phase generator and lo buffers. external i and q baseband signals are applied to the differential baseband input pins, bbpi, bbmi, and bbpq, bbmq. these voltage signals are converted to currents and translated to rf frequency by means of double-balanced up-converting mixers. the mixer outputs are combined in an rf output buffer, which also transforms the output impedance to 50. the center frequency of the resulting rf signal is equal to the lo signal frequency. the lo input drives a phase shifter which splits the lo signal into in- phase and quadrature lo signals. these lo signals are then applied to on-chip buffers which drive the up-conversion mixers. in most applications, the lop input is driven by the lo source via an optional matching network, while the lom input is terminated with 50 to rf ground via a similar optional matching network. the rf output is single-ended and internally 50 matched. baseband interface the circuit is optimized for a common mode voltage of 0.5v which should be externally applied. the baseband pins should not be left ? oating because the internal pnps base current will pull the common mode voltage higher than the 0.6v limit. this condition may damage the part. in shut-down mode, it is recommended to have a termination to ground or to a 0.5v source with a value lower than 1k. the pnps base current is about C68a in normal operation. the baseband inputs (bbpi, bbmi, bbpq, bbmq) present a single-ended input impedance of about C7.4k each. because of the negative input impedance, it is important to keep the source resistance at each baseband input low enough such that the parallel value remains positive vs baseband frequency. at each of the four baseband inputs, a capacitor of 4pf in series with 30 is connected to ground. this is in parallel with a pnp emitter follower (see figure 1). the baseband bandwidth depends on the source impedance. for a 25 source impedance, the baseband bandwidth (C1db) is about 300mhz. if a 5.6nh s eries inductor is applications information inserted in each of the four baseband connections, the C1db baseband bandwidth increases to about 800mhz. it is recommended to include the baseband input impedance in the baseband lowpass ? lter design. the input impedance of each baseband input is given in table 1. table 1. single-ended bb port input impedance vs frequency for en = high and v cmbb = 0.5v dc frequency (mhz) bb input impedance reflection coefficient mag angle 0.1 C10578 C j263 1.01 C0.02 1 C8436 C j1930 1.011 C0.15 2 C6340 C j3143 1.013 C0.36 4 C3672 C j3712 1.014 C0.78 8 C1644 C j2833 1.015 C1.51 16 C527 C j1765 1.016 C2.98 30 C177 C j1015 1.017 C5.48 60 C45.2 C j514 1.017 C11 100 C13.2 C j306 1.014 C18.5 140 C0.2 C j219 1 C25.7 200 4.5 C j151 0.982 C36.6 300 10.4 C j99.4 0.921 C52.9 400 12.3 C j72.4 0.854 C68.2 500 14.7 C j57.5 0.780 C79.9 600 15.5 C j46.3 0.720 C91.4 the baseband inputs should be driven differentially; otherwise, the even-order distortion products may degrade the overall linearity performance. typically, a dac will figure 1. simpli? ed circuit schematic of the ltc5598 (only i-half is drawn) bbpi bbmi gnd lomi lopi gndrf rf from q 55682 f01 30 30 4pf 4pf ltc5598 v cc1 = 5v v cmbb = 0.5v dc v cc2 = 5v buffer
ltc5598 10 5598f applications information be the signal source for the ltc5598. a reconstruction ? lter should be placed between the dac output and the ltc5598s baseband inputs. in figure 2 a typical baseband interface is shown, using a ? fth-order lowpass ladder ? lter. in table 3. in table 4 and 5, the lop port input impedance is given for en = high and low under the condition of p lo = 10dbm. figure 4 shows the lop port return loss for the standard demo board (schematic is shown in figure 10) when the lom port is terminated with 50 to gnd. the values of l1, l2, c9 and c10 are chosen such that the bandwidth for the lop port of the standard demo board is maximized while meeting the lo input return loss s 11, on < C10db. table 2. lop port input impedance vs frequency for en = high and p lo = 0dbm (lom ac coupled with 50 to ground). frequency (mhz) lo input impedance reflection coefficient mag angle 0.1 333 C j10.0 0.739 C0.5 1 318 C j59.9 0.737 C3.3 2 285 C j94.7 0.728 C6.1 4 227 C j120 0.708 C10.6 8 154 C j124 0.678 C18.7 16 89.9 C j95.4 0.611 C33.0 30 60.4 C j60.6 0.420 C41.3 60 54.8 C j35.8 0.489 C51.5 100 43.6 C j24.4 0.261 C89.9 200 37.9 C j17.3 0.235 C113 400 31.8 C j12.4 0.266 C137 800 23.6 C j8.2 0.374 C156 1000 19.8 C j5.5 0.437 C165 1250 16.0 C j1.8 0.515 C175 1500 13.6 + j2.4 0.574 174 1800 12.1 + j7.3 0.618 162 bbpi r2a 100 7 l2a l2b gnd 0.5v dc 0.5v dc c3 r2b 100 7 bbmi 5598 f02 r1a 100 7 r1b 100 7 l1a l1b c2 c1 dac 0ma to 20ma 0ma to 20ma figure 2. baseband interface with 5th order filter and 0.5v cm dac (only i channel is shown) for each baseband pin, a 0 to 1v swing is developed corresponding to a dac output current of 0ma to 20ma. the maximum sinusoidal single side-band rf output power is about +7.3dbm for full 0v to 1v swing on each i- and q- channel baseband input (2v pp, diff ). lo section the internal lo chain consists of poly-phase phase shifters followed by lo buffers. the lop input is designed as a single-ended input with about 50 input impedance. the lom input should be terminated with 50 through a dc blocking capacitor. the lop and lom inputs can be driven differentially in case an exceptionally low large-signal output noise ? oor is required (see graph 5598 g20b). a simpli? ed circuit schematic for the lop, lom, capa and capb inputs is given in figure 3. a feedback path is implemented from the lo buffer outputs to the lo inputs in order to minimize offsets in the lo chain by storing the offsets on c5, c7 and c8 (see figure 10). optional capacitor c8 improves the image rejection below 100mhz (see graph 5598 g20a). because of the feedback path, the input impedance for p lo = 0dbm is somewhat different than for p lo = 10dbm for the lower part of the operating frequency range. in table 2, the lop port input impedance vs frequency is given for en = high and p lo = 0dbm. for en = low and p lo = 0dbm, the input impedance is given v cc1 2.8v (4.3v in shutdown) lop lom capa capb 5598 f03 + figure 3. simpli? ed circuit schematic for the lop, lom, capa and capb inputs.
ltc5598 11 5598f applications information table 3. lop port input impedance vs frequency for en = low and p lo = 0dbm (lom ac coupled with 50 to ground). frequency (mhz) lo input impedance reflection coefficient mag angle 0.1 1376 C j84.4 0.930 C0.3 1 541 C j1593 0.980 C3.2 2 177 C j877 0.977 C6.2 4 75.3 C j452 0.965 C12.2 8 49.2 C j228 0.918 C23.6 16 43.3 C j117 0.784 C41.8 30 40.7 C j64.1 0.585 C62.7 60 39.1 C j34.6 0.382 C86 100 37.6 C j23.8 0.296 C102 200 33.4 C j16.4 0.275 C124 400 27.5 C j11.1 0.320 C145 800 20.1 C j4.9 0.430 C167 1000 17.5 C j1.6 0.479 C176 1250 15.3 + j2.1 0.532 175 1500 13.8 + j5.6 0.571 167 1800 12.8 + j9.7 0.605 157 table 4. lop port input impedance vs frequency for en = high and p lo = 10dbm (lom ac coupled with 50 to ground). frequency (mhz) lo input impedance reflection coefficient mag angle 0.1 360-j14.8 0.756 C0.7 1 349-j70.5 0.758 C3.2 2 311-j113 0.752 C6.0 4 240-j148 0.739 C10.9 8 148-j146 0.715 C19.7 16 81.3-j102 0.641 C35.2 30 55.4-j61.6 0.506 C54.7 60 45.7-j34.4 0.341 C77.4 100 43.0-j24.1 0.261 C91.6 200 38.0-j17.1 0.234 C114 400 32.0-j12.5 0.265 C137 800 23.6-j8.3 0.374 C156 1000 19.8-j5.6 0.438 C165 1250 15.8-j1.7 0.520 C176 1500 13.5+j2.4 0.575 174 1800 12.0+j7.3 0.619 162 table 5. lop port input impedance vs frequency for en = low and p lo = 10dbm (lom ac coupled with 50 to ground). frequency (mhz) lo input impedance reflection coefficient mag angle 0.1 454 C j30.5 0.802 C0.9 1 423 C j102 0.780 C3.2 2 365 C j165 0.796 C5.9 4 249 C j219 0.798 C11.4 8 117 C j179 0.781 C22.4 16 60.7 C j106 0.697 C40.3 30 43.1 C j62.0 0.559 C62.4 60 38.6 C j34.6 0.386 C86.7 100 37.6 C j23.9 0.297 C102 200 33.5 C j16.5 0.274 C124 400 27.6 C j11.3 0.319 C145 800 20.2 C j5.1 0.429 C166 1000 17.7 C j1.7 0.478 C175 1250 15.2 + j2.0 0.533 175 1500 13.9 + j5.4 0.570 167 1800 12.9 + j9.5 0.604 158 frequency (mhz) 1 return loss (db) C10 C5 C15 C20 100 10 1000 C25 0 5598 f04 en = low; p lo = 0dbm en = low; p lo = 10dbm en = high; p lo = 0dbm en = high; p lo = 10dbm c9, c10: 2.2pf; l1, l2: 3.3nh; c5, c7: 10nf figure 4. lop port return loss vs frequency for standard board (see figure 10)
ltc5598 12 5598f the lop port return loss for the low end of the operating frequency range can be optimized using extra 120 terminations at the lo inputs (replace c9 and c10 with 120 resistors, see figure 10), and is shown in figure 5. the large-signal noise ? gure can be improved with a higher lo input power. however, if the lo input power is too large and causes internal clipping in the phase shifter section, the image rejection can be degraded rapidly. this clipping point depends on the supply voltage, lo frequency, temperature and single-ended vs differential lo drive. at f lo = 140mhz, v cc = 5v, t = 25c and single-ended lo drive, this clipping point is at about 16.6dbm. for 4.5v it lowers to 14.6dbm. for differential drive with v cc = 5v it is about 20dbm. the differential lo port input impedance for en = high and p lo = 10dbm is given in table 6. table 6. lop - lom port differential input impedance vs frequency for en = high and p lo = 10dbm frequency (mhz) lo differential input impedance 0.1 642 C j25.7 1.0 626 C j112 2.0 572 C j204 4.0 429 C j305 8.0 222 C j287 16 102 C j181 30 64.2 C j104 60 50.9 C j58.9 100 46.2 C j40.2 200 37.4 C j28.6 400 28.3 C j19.4 800 20.0 C j10.6 1000 17.5 C j7.9 1250 16.6 C j2.7 1500 17.3 + j3.3 1800 20.6 + j10.2 rf section after upconversion, the rf outputs of the i and q mixers are combined. an on-chip buffer performs internal differential to single-ended conversion, while transforming the output impedance to 50. table 7 shows the rf port output impedance vs frequency for en = high. applications information frequency (mhz) 1 return loss (db) C5 C6 C10 C12 100 10 1000 C14 C4 5598 f05 en = low; p lo = 0dbm en = low; p lo = 10dbm en = high; p lo = 0dbm en = high; p lo = 10dbm c9, c10: 120; l1, l2: 0; c5, c7: 100nf figure 5. lo port return loss vs frequency optimized for low frequency (see figure 10) the lop port return loss for the high end of the operating frequency range can be optimized using slightly different values for c9, c10 and l1, l2 (see figure 6). frequency (mhz) 1000 return loss (db) C10 C20 C30 1400 1200 1600 1800 2000 C40 0 5598 f06 en = low en = high c9, c10: 2.7pf; l1, l2: 1.5nh; c5, c7: 10nf figure 6. lo port return loss vs frequency optimized for high frequency (see figure 10) the third-harmonic rejection on the applied lo signal is recommended to be equal or better than the desired image rejection performance since third-harmonic lo content can degrade the image rejection severely. image rejection is not sensitive to second-harmonic lo content.
ltc5598 13 5598f table 7. rf output impedance vs frequency for en = high frequency (mhz) rf output impedance reflection coefficient mag angle 0.1 59.0 C j0.6 0.083 C3.6 1 58.5 C j2.1 0.081 C12.7 2 57.3 C j3.5 0.076 C23.6 4 54.6 C j4.5 0.061 C41.6 8 51.9 C j3.6 0.040 C60.8 16 50.5 C j2.1 0.022 C74.8 30 50.2 C j1.1 0.011 C80 60 50 C j0.5 0.005 C86.5 100 50 C j0.2 0.002 C84.9 200 49.7 + j0 0.003 177.4 400 48.9 + j0.3 0.011 162 800 46.1 + j0.4 0.041 173.3 1000 44.5 + j0.2 0.058 178 1250 42.8 + j0 0.077 C179.7 1500 41.2 C j0.1 0.097 C179.4 1800 39.9 + j0.4 0.113 177.4 the rf port output impedance for en = low is given in table 8. it is roughly equivalent to a 1.3pf capacitor to ground. table 8. rf output impedance vs frequency for en = low frequency (mhz) lo input impedance reflection coefficient mag angle 100 82.3 C j1223 0.995 C4.6 200 51.1 C j618 0.987 C9.2 400 35.3 C j310 0.965 C18.1 800 24.4 C j148 0.906 C36.6 1000 20.4 C j114 0.878 C46.4 1250 17 C j87 0.847 C58.4 1500 14.7 C j68 0.818 C70.7 1800 13.1 C j54 0.785 C84.3 in figure 7 the simpli? ed circuit schematic of the rf output buffer is drawn. a plot of the rf port return loss vs frequency is drawn in figure 8 for en = high and low. enable interface figure 9 shows a simpli? ed schematic of the en pin interface. the voltage necessary to turn on the ltc5598 is 2v. to disable (shut down) the chip, the enable voltage must be below 1v. if the en pin is not connected, the chip is enabled. this en = high condition is assured by the 125k on-chip pull-up resistor. it is important that the voltage at the en pin does not exceed v cc by more than 0.3v. should applications information rf 1k 1.8v 4.6v 48 48 1k 1v 2.8v from internal mixers internal bias 5598 f07 v cc2 figure 7. simpli? ed circuit schematic of the rf output frequency (mhz) 1 return loss (db) C10 C30 C20 C40 100 1000 10 C60 C50 0 5598 f08 en = low en = high c6 = 220nf, see figure 10 figure 8. rf port return loss vs frequency en v cc1 125k 50k 2v 3v internal enable circuit 5598 f09 figure 9: en pin interface
ltc5598 14 5598f applications information figure 12. bottom side of evaluation board figure 11. component side of evaluation board c8 470nf c6 10nf c7 10nf c5 10nf c3 1nf r2 5.6 r1 1 c4 4.7f c1 4.7f c2 1nf en gnd lop lom gnd capa 1 2 3 4 5 6 18 17 16 15 14 13 7 8 9 10 11 12 25 24 23 22 21 20 19 v cc2 gndrf rf nc gndrf nc gnd gnd bbpi bbmi gnd v cc1 capb gnd bbmq bbpq gnd gnd gnd bbmq en bbpq rf out u1 ltc5598 board number: dc1455a j6 j1 lop j3 lom j5 j7 j2 j4 gnd 5598 f10 c10 2.2pf c9 2.2pf l1 3.3nh l2 3.3nh v cc bbmi bbpi figure 10. evaluation circuit schematic this occur, the supply current could be sourced through the en pin esd protection diodes, which are not designed to carry the full supply current, and damage may result. evaluation board figure 10 shows the evaluation board schematic. a good ground connection is required for the exposed pad. if this is not done properly, the rf performance will degrade. additionally, the exposed pad provides heat sinking for the part and minimizes the possibility of the chip overheating. resistors r1 and r2 reduce the charging current in capacitors c1 and c4 (see figure 10) and will reduce supply ringing during a fast power supply ramp-up in case an inductive cable is connected to the v cc and gnd turrets. for en = high, the voltage drop over r1 and r2 is about 0.15v. if a power supply is used that ramps up slower than 10v/s and limits the overshoot on the supply below 5.6v, r1 and r2 can be omitted. the ltc5598 can be used for base-station applications with various modulation formats. figure 13 shows a typical application.
ltc5598 15 5598f information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description uf package 24-lead (4mm 4mm) plastic qfn (reference ltc dwg # 05-08-1697) 4.00 p 0.10 (4 sides) note: 1. drawing proposed to be made a jedec package outline mo-220 variation (wggd-x)to be approved 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side, if present 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package pin 1 top mark (note 6) 0.40 p 0.10 24 23 1 2 bottom viewexposed pad 2.45 p 0.10 (4-sides) 0.75 p 0.05 r = 0.115 typ 0.25 p 0.05 0.50 bsc 0.200 ref 0.00 C 0.05 (uf24) qfn 0105 recommended solder pad pitch and dimensions 0.70 p 0.05 0.25 p 0.05 0.50 bsc 2.45 p 0.05 (4 sides) 3.10 p 0.05 4.50 p 0.05 package outline pin 1 notch r = 0.20 typ or 0.35 s 45 o chamfer figure 13: 5mhz to 1600mhz direct conversion transmitter application 90 o 0 o ltc5598 nc 21 22 1 10 9 2, 5, 8, 11, 12, 19, 20, 23, 25 467 16 13, 15 14, 17 10nf 50 3 18, 24 10nf 470nf 10nf baseband generator pa rf = 5mhz to 1600mhz 1nf x2 4.7f x2 en 5v v-i v-i i-channel q-channel v cc 5598 f13 i-dac q-dac vco/synthesizer applications information
ltc5598 16 5598f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2009 lt 0509 ? printed in usa related parts part number description comments infrastructure lt5514 ultralow distortion, if ampli? er/adc driver with digitally controlled gain 850mhz bandwidth, 47dbm oip3 at 100mhz, 10.5db to 33db gain control range lt5517 40mhz to 900mhz quadrature demodulator 21dbm iip3, integrated lo quadrature generator lt5518 1.5ghz to 2.4ghz high linearity direct quadrature modulator 22.8dbm oip3 at 2ghz, C158.2dbm/hz noise floor, 50 single-ended rf and lo ports, 4-channel w-cdma acpr = C64dbc at 2.14ghz lt5519 0.7ghz to 1.4ghz high linearity upconverting mixer 17.1dbm iip3 at 1ghz, integrated rf output transformer with 50 matching, single-ended lo and rf ports operation lt5520 1.3ghz to 2.3ghz high linearity upconverting mixer 15.9dbm iip3 at 1.9ghz, integrated rf output transformer with 50 matching, single-ended lo and rf ports operation lt5521 10mhz to 3700mhz high linearity upconverting mixer 24.2dbm iip3 at 1.95ghz, nf = 12.5db, 3.15v to 5.25v supply, single-ended lo port operation lt5522 600mhz to 2.7ghz high signal level downconverting mixer 4.5v to 5.25v supply, 25dbm iip3 at 900mhz, nf = 12.5db, 50 single-ended rf and lo ports lt5527 400mhz to 3.7ghz high signal level downconverting mixer iip3 = 23.5dbm and nf = 12.5dbm at 1900mhz, 4.5v to 5.25v supply, i cc = 78ma, conversion gain = 2db. lt5528 1.5ghz to 2.4ghz high linearity direct quadrature modulator 21.8dbm oip3 at 2ghz, C159.3dbm/hz noise floor, 50 , 0.5v dc baseband interface, 4-channel w-cdma acpr = C66dbc at 2.14ghz lt5554 broadband ultra low distortion 7-bit digitally controlled vga 48dbm oip3 at 200mhz, 1.4nv/ hz input-referred noise, 2db to 18db gain range, 0.125db gain step size lt5557 400mhz to 3.8ghz high signal level downconverting mixer iip3 = 23.7dbm at 2600mhz, 23.5dbm at 3600mhz, i cc = 82ma at 3.3v lt5560 ultra-low power active mixer 10ma supply current, 10dbm iip3, 10db nf, usable as up- or down-converter. lt5568 700mhz to 1050mhz high linearity direct quadrature modulator 22.9dbm oip3 at 850mhz, C160.3dbm/hz noise floor, 50 , 0.5v dc baseband interface, 3-ch cdma2000 acpr = C71.4dbc at 850mhz lt5571 620mhz - 1100mhz high linearity quadrature modulator 21.7dbm oip3 at 900mhz, C159dbm/hz noise floor, high-ohmic 0.5v dc baseband interface lt5572 1.5ghz to 2.5ghz high linearity direct quadrature modulator 21.6dbm oip3 at 2ghz, C158.6dbm/hz noise floor, high-ohmic 0.5v dc baseband interface, 4-ch w-cdma acpr = C67.7dbc at 2.14ghz lt5575 800mhz to 2.7ghz high linearity direct conversion i/q demodulator 50, single-ended rf and lo ports, 28dbm iip3 at 900mhz, 13.2dbm p1db, 0.04db i/q gain mismatch, 0.4 i/q phase mismatch lt5579 1.5ghz to 3.8ghz high linearity upconverting mixer 27.3dbm oip3 at 2.14ghz, 9.9db noise floor, 2.6db conversion gain, C35dbm lo leakage rf power detectors lt c ? 5505 rf power detectors with >40db dynamic range 300 mhz to 3ghz, temperature compensated, 2.7v to 6v supply ltc5507 100khz to 1000mhz rf power detector 100khz to 1ghz, temperature compensated, 2.7v to 6v supply ltc5508 300mhz to 7ghz rf power detector 44db dynamic range, temperature compensated, sc70 package ltc5509 300mhz to 3ghz rf power detector 36db dynamic range, low power consumption, sc70 package ltc5530 300mhz to 7ghz precision rf power detector precision v out offset control, shutdown, adjustable gain ltc5531 300mhz to 7ghz precision rf power detector precision v out offset control, shutdown, adjustable offset ltc5532 300mhz to 7ghz precision rf power detector precision v out offset control, adjustable gain and offset lt5534 50mhz to 3ghz log rf power detector with 60db dynamic range 1db output variation over temperature, 38ns response time, log linear response ltc5536 precision 600mhz to 7ghz rf power detector with fast comparator output 25ns response time, comparator reference input, latch enable input, C26dbm to +12dbm input range lt5537 wide dynamic range log rf/if detector low frequency to 1ghz, 83db log linear dynamic range lt5538 3.8ghz wide dynamic range log detector 75db dynamic range, 1db output variation over temperature lt5570 2.7ghz rms power detector fast responding, up to 60db dynamic range, 0.3db accuracy over temperature lt5581 40db dynamic range rms detector 10mhz to 6ghz, 1db accuracy over temperature, 1.4ma at 3.3v supply

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