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2-491 product description ordering information typical applications features functional block diagram rf micro devices, inc. 7628 thorndike road greensboro, nc 27409, usa tel (336) 664 1233 fax (336) 664 0454 http://www.rfmd.com optimum technology matching? applied si bjt gaas mesfet gaas hbt si bi-cmos sige hbt si cmos ingap/hbt gan hemt sige bi-cmos pcs in pcs out band select tx enable vramp vbatt gsm in gsm out vbatt 37 40 41 45 42 48 31 6 43 fully integrated power control circuit rf3146a dual-band gsm850/pcs power amp module ? 3v dual-band gsm handsets ? commercial and consumer systems ? portable battery-powered equipment ? gsm850/pcs products ? gprs class 12 compatible ? power star tm module the rf3146a is a high-power, high-efficiency power amplifier module with integrated power control. the device is a self-contained 7mmx7mmx0.9mm lead frame module (lfm) with 50 input and output terminals. the power control function is also incorporated, eliminat- ing the need for directional couplers, detector diodes, power control asics and other power control circuitry; this allows the module to be driven directly from the dac output. the device is designed for use as the final rf amplifier in gsm850, and pc s handheld digital cellular equipment and other applications in the 824mhz to 849mhz, and 1850mhz to 1910mhz bands. on-board power control provides over 50db of control range with an analog voltage input; and, power down with a logic ?low? for standby operation. ? integrated v reg ? complete power control solution ? +35dbm gsm output power at 3.5v ? +33dbm pcs output power at 3.5v ? 60% gsm and 55% pcs eff ? 7mmx7mmx0.9mm package size rf3146a dual-band gsm850/pcs power amp module rf3146a sb power amp module 5-piece sample pack rf3146apcba-41x fully assembled evaluation board 0 rev a3 051011 dimensions in mm. shaded lead is pin 1. -b- 2 plcs 0.10 c b 2 plcs 0.10 c a 2 plcs 0.10 c b 3.50 typ 3.37 typ -a- 2 plcs 0.10 c a 7.00 typ 6.75 typ 0.70 0.65 0.90 0.85 0.08 c 0.05 0.00 seating plane -c- 0.10 c ab m 2.20 1.90 5.25 4.95 0.50 0.30 typ 0.30 0.60 0.24 typ 0.60 0.24 typ 0.30 0.18 0.50 package style: lfm, 48-pin, 7mm x7mmx0.9mm 9 9 rohs compliant & pb-free product
2-492 rf3146a rev a3 051011 absolute maximum ratings parameter rating unit supply voltage -0.3 to +6.0 v dc power control voltage (v ramp ) -0.3 to +1.8 v input rf power +10 dbm max duty cycle 50 % output load vswr 10:1 operating case temperature -20 to +85 c storage temperature -55 to +150 c parameter specification unit condition min. typ. max. overall power control v ramp power control ?on? 1.5 v max. p out , voltage supplied to the input power control ?off? 0.2 0.25 v min. p out , voltage supplied to the input v ramp input capacitance 15 20 pf dc to 2mhz v ramp input current 10 av ramp =v ramp max turn on/off time 2 sv ramp =0.2v to v ramp max tx enable ?on? 1.5 v tx enable ?off? 0.5 v gsm band enable 0.5 v pcs band enable 1.9 v overall power supply power supply voltage 3.0 3.5 5.5 v specifications v nominal operating limits power supply current 1 ap in <-30dbm, tx enable=low, temp=-20c to +85c ma v ramp =0.2v, tx enable=high overall control signals band select ?low? 0 0 0.5 v band select ?high? 1.9 2.0 3.0 v band select ?high? current 20 50 a tx enable ?low? 0 0 0.5 v tx enable ?high? 1.5 2.0 3.0 v tx enable ?high? current 1 2 a caution! esd sensitive device. rf micro devices believes the furnished information is correct and accurate at the time of this printing. rohs marking based on eudirective2002/95/ec (at time of this printing). however, rf micro devices reserves the right to make changes to its products without notice. rf micro devices does not assume responsibility for the use of the described product(s).
2-493 rf3146a rev a3 051011 parameter specification unit condition min. typ. max. overall (gsm850 mode) te m p = + 2 5 c, v batt =3.5v, v ramp =v ramp max , p in =3dbm, freq=824mhz to 849mhz, 25% duty cycle, pulse width=1154 s operating frequency range 824 to 849 mhz maximum output power +34.2 dbm temp = 25c, v batt =3.5v, v ramp =v ramp max +32.0 dbm temp=+85 c, v batt =3.0v, v ramp =v ramp max total efficiency 47 55 % at p out max , v batt =3.5v input power range 0 +3 +5 dbm maximum output power guaranteed at mini- mum drive level output noise power -88 -81 dbm rbw=100khz, 869mhz to 894mhz, p out > +5dbm forward isolation 1 -50 -35 dbm txenable=low, p in =+5dbm forward isolation 2 -35 -15 dbm txenable=high, p in =+5dbm, v ramp =0.2v cross band isolation at 2f 0 -18 dbm v ramp =0.2v to v ramp _r p second harmonic -15 -7 dbm v ramp =0.2v to v ramp _r p third harmonic -25 -15 dbm v ramp =0.2v to v ramp _r p all other non-harmonic spurious -36 dbm v ramp =0.2v to v ramp max input impedance 50 input vswr 2.5:1 v ramp =0.2v to v ramp max output load vswr stability 8:1 spurious<-36dbm, rbw=3mhz set v ramp where p out < 34.2dbm into 50 load output load vswr ruggedness 10:1 set v ramp where p out < 34.2dbm into 50 load. no damage or permanent degradation to part. output load impedance 50 load impedance presented at rf out pad power control v ramp power control range 55 db v ramp =0.2v to v ramp max notes: v ramp max =0.4*v batt +0.06< 1.5v v ramp _r p =v ramp set for 34.2dbm at nominal conditions.
2-494 rf3146a rev a3 051011 parameter specification unit condition min. typ. max. overall (pcs mode) te m p = 2 5 c, v batt =3.5v, v ramp =v ramp max , p in =3dbm, freq=1850mhz to 1910mhz, 25% duty cycle, pulse width=1154 s operating frequency range 1850 to 1910 mhz maximum output power +32.0 dbm temp=25c, v batt =3.5v, v ramp =v ramp max , 1850mhz to 1910mhz 30 dbm temp=+85c, v batt =3.0v, v ramp =v ramp max total efficiency 48 55 % at p out max, v batt =3.5v input power range 0 +3 +5 dbm full output power guaranteed at minimum drive level output noise power -85 -80 dbm rbw=100khz, 1930mhz to 1990mhz, p out > 0dbm, v batt =3.5v forward isolation 1 -40 -33 dbm tx_enable=low, p in =+5dbm forward isolation 2 -20 -15 dbm txenable=high, v ramp =0.2v, p in =+5dbm second harmonic -15 -7 dbm v ramp =0.2v to v ramp _r p third harmonic -20 -15 dbm v ramp =0.2v to v ramp _r p all other non-harmonic spurious -36 dbm v ramp =0.2v to v ramp max input impedance 50 input vswr 2.5:1 v ramp =0.2v to v ramp max output load vswr stability 8:1 spurious<-36dbm, rbw=3mhz set v ramp where p out < 32.0dbm into 50 load output load vswr ruggedness 10:1 set v ramp where p out < 32.0dbm into 50 load. no damage or permanent degradation to part. output load impedance 50 load impedance presented at rf out pin power control v ramp power control range 50 db v ramp =0.2v to v ramp max , p in =+5dbm notes: v ramp max =0.4*v batt +0.06< 1.5v v ramp _r p =v ramp set for 32.0dbm at nominal conditions.
2-495 rf3146a rev a3 051011 pin function description interface schematic 1nc internal circuit node. do not externally connect. 2vcc2 gsm controlled voltage input to the gsm driver stage. this voltage is part of the power control function for the module. this node must be con- nected to vcc out. this pin should be externally decoupled. 3nc internal circuit node. do not externally connect. 4gnd internally connected to the package base. 5gnd internally connected to the package base. 6 gsm850 out rf output for the gsm850 band. this is a 50 output. the output matching circuit and dc-block are internal to the package. 7gnd internally connected to the package base. 8nc internal circuit node. do not externally connect. 9nc internal circuit node. do not externally connect. 10 nc internal circuit node. do not externally connect. 11 nc internal circuit node. do not externally connect. 12 nc internal circuit node. do not externally connect. 13 nc no internal or external connection. 14 nc internal circuit node. do not externally connect. 15 nc internal circuit node. do not externally connect. 16 nc internal circuit node. do not externally connect. 17 nc internal circuit node. do not externally connect. 18 vcc3 gsm controlled voltage input to the gsm output stage. this voltage is part of the power control function for the module. this node must be con- nected to vcc out. this pin should be externally decoupled. 19 vcc out controlled voltage output to feed vcc2 and vcc3. this voltage is part of the power control function for the module. it cannot be connected to any pins other than vcc2 and vcc3. 20 vcc out controlled voltage output to feed vcc2 and vcc3. this voltage is part of the power control function for the module. it cannot be connected to any pins other than vcc2 and vcc3. 21 vcc3 pcs controlled voltage input to the pcs output stage. this voltage is part of the power control function for the module. this node must be con- nected to vcc out. this pin should be externally decoupled. see pin 18. 22 nc internal circuit node. do not externally connect. 23 nc internal circuit node. do not externally connect. 24 nc no internal or external connection. 25 nc internal circuit node. do not externally connect. 26 nc internal circuit node. do not externally connect. 27 nc internal circuit node. do not externally connect. 28 nc internal circuit node. do not externally connect. 29 nc internal circuit node. do not externally connect. 30 gnd internally connected to the package base. vcc2 vcc3 rf out output match vcc3
2-496 rf3146a rev a3 051011 pin function description interface schematic 31 pcs out rf output for the pcs bands. this is a 50 output. the output match- ing circuit and dc-block are internal to the package. see pin 6. 32 gnd internally connected to the package base. 33 nc internal circuit node. do not externally connect. 34 gnd internally connected to the package base. 35 vcc2 pcs controlled voltage input to the pcs driver stage. this voltage is part of the power control function for the module. this node must be con- nected to vcc out. this pin should be externally decoupled. see pin 2. 36 nc no internal connection. connect to ground plane close to the package pin. 37 pcs in rf input to the pcs band. this is a 50 output. 38 nc no internal connection. connect to ground plane close to the package pin. 39 vcc1 pcs controlled voltage on the gsm and pcs preamplifier stages. this volt- age is applied internal to the package. this pin should be externally decoupled. 40 band sel allows external control to select the gsm or pcs bands with a logic high or low. a logic low enables the gsm bands, whereas a logic high enables the pcs bands. 41 tx enable this signal enables the pa module for operation with a logic high. both bands are disabled with a logic low. 42 vbatt power supply for the module. this pin should be externally decoupled and connected to the battery. 43 vbatt power supply for the module. this pin should be externally decoupled and connected to the battery. 44 nc internal circuit node. do not externally connect. 45 vramp ramping signal from dac. a simple rc filter may be required depend- ing on the selected baseband. 46 vcc1 gsm internally connected to vcc1 (pin 39). no external connection required. see pin 39. 47 gnd1 gsm ground connection for the gsm preamplifier stage. connect to ground plane close to the package pin. 48 gsm850 in rf input to the gsm band. this is a 50 input. see pin 37. pkg base gnd connect to ground plane with multiple via holes. see recommended footprint. vcc1 rf in vcc1 gsm ctrl pcs ctrl band sel tx en tx en vbatt tx on - + vramp
2-497 rf3146a rev a3 051011 pin out 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 gsm850 out nc vcc2 gsm nc gnd gnd gnd nc nc nc nc nc nc nc nc nc nc vcc3 gsm vcc out vcc out vcc3 pcs nc nc nc nc nc nc nc nc nc gnd gnd gnd nc pcs out pcs in vcc2 pcs nc gnd1 gsm band sel tx enable vbatt vbatt nc vramp vcc1 gsm gsm850 in vcc1 dcs/pcs
2-498 rf3146a rev a3 051011 application schematic 4.7 f vbatt 1 nf 1 nf 100 pf 10 nf 1 nf 15 k gsm850 in pcs in vramp pcs out gsm850 out v cc1 tx en band sel 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 fully integrated power control circuit from v cc1 v cc v cc1 : internally supplied. see pin function note.
2-499 rf3146a rev a3 051011 evaluation board schematic c2 4.7 f vbatt c6 1 nf vcc1 50 ? strip pcs in c4 dnp 50 ? strip pcs out 50 ? strip gsm850 out c9 1 nf r3 100 k r1 15 k r4 100 k 50 ? strip gsm850 in vramp tx en r2 100 k band sel c8 1 nf 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 from v cc1 v cc v cc1 : internally supplied. see pin function note. c13 100 pf c10 10 nf
2-500 rf3146a rev a3 051011 evaluation board layout board size 2.0? x 2.0? board thickness 0.032?, board material fr-4, multi-layer
2-501 rf3146a rev a3 051011 theory of operation overview the rf3146a is a dual-band gsm850, and pcs1900 power amplifier module that incorporates an indirect closed loop method of power control. this simplifies the phone desi gn by eliminating the need for the complicated control loop design. the indirect closed loop appears as an open loop to the user and can be driven directly from the dac output in the baseband circuit. theory of operation the indirect closed loop is essentially a closed loop method of power control that is invisible to the user. most power con- trol systems in gsm sense either forward power or collecto r/drain current. the rf3146a does not use a power detector. a high-speed control loop is incorporated to regulate the co llector voltage of the amplifier while the stage are held at a constant bias. the v ramp signal is multiplied by a factor of 2.65 and the collector voltage for the second and third stages are regulated to the multiplied v ramp voltage. the basic circuit is shown in the following diagram. by regulating the power, the stages are held in saturation across all power levels. as the required output power is decreased from full power down to 0dbm, the collector voltage is also decreased. this regulation of output power is demonstrated in equation 1 where the relationship between collector voltage and output power is shown. although load impedance affects output power, supply fluctuations are th e dominate mode of power variations. with the rf3146a reg- ulating collector voltage, the dominant mode of power fluctuations is eliminated. (eq. 1) there are several key factors to consider in the implementation of a transmitter solution for a mobile phone. some of them are: ? current draw and system efficiency ? power variation due to supply voltage ? power variation due to frequency ? power variation due to temperature ? input impedance variation ? noise power ? loop stability ? loop bandwidth variations across power levels ? burst timing and transient spectrum trade offs ? harmonics rf in tx enable rf out h(s) vramp tx enable vbatt p dbm 10 2 v cc v sat ? ? () 2 8 r load 10 3 ? ?? ------------------------------------------- log ? =
2-502 rf3146a rev a3 051011 output power does not vary due to supply voltage under normal operating conditions if v ramp is sufficiently lower than v batt . by regulating the collector voltage to the pa the voltag e sensitivity is essentially eliminated. this covers most cases where the pa will be operated. ho wever, as the battery discharges and approaches its lower power range the maximum output power from the pa will also drop slight ly. in this case it is im portant to also decrease v ramp to prevent the power control from inducing switching transients. these tr ansients occur as a result of the control loop slowing down and not regulating power in accordance with v ramp . the switching transients due to low battery conditions are regulated by incorporating the following relationship limiting the maximum v ramp voltage (equation 2). although no compensation is required for typical battery conditions, the bat- tery compensation required for extreme conditions is covered by the relationship in equation 2. this should be added to the terminal software. (eq. 2) due to reactive output matches, there are output power variations across frequency. there are a number of components that can make the effects greater or less. the components following the power amplifier often have insertion loss variation with respect to frequency. usually, there is some length of microstrip that follows the power amplifier. there is also a frequency response found in directional cou- plers due to variation in the coupling factor over frequency, as well as the sensitivity of the detector diode. since the rf3146a does not use a directional coupler with a diode detector, these variations do not occur. input impedance variation is found in most gsm power amplifiers. this is due to a device phenomena where c be and c cb (c gs and c sg for a fet) vary over the bias voltage. the same principle used to make varactors is present in the power amplifiers. the junction capacitance is a function of the bias across the junction. this produces input impedance variations as the vapc voltage is swep t. although this could pr esent a problem with freque ncy pulling the transmit vco off frequency, most synthesizer designers use very wide loop bandwidths to quickly compensate for frequency variations due to the load variations presented to the vco. the rf3146a presents a very constant load to the vco. this is because all stages of the rf3146a are run at constant bias. as a result, there is constant reactance at the base emitter and base collector junction of the input stage to the power amplifier. noise power in pa's where output power is controlled by changing the bias voltage is often a problem when backing off of output power. the reason is that the gain is changed in all stages and according to the noise formula (equation 3), (eq. 3) the noise figure depends on noise factor and gain in all stages. because the bias point of the rf3146a is kept constant the gain in the first stage is always high and the overall noise power is not increased when decreasing output power. power control loop stability ofte n presents many challe nges to transmitter de sign. designing a prop er power control loop involves trade-offs affecting stability, transient spectrum and burst timing. in conventional architectures the pa gain (db/ v) varies across different power levels, and as a result the loop bandwidth also varies. with some power amplifiers it is possible for the pa gain (control slope) to change from 100db/v to as high as 1000db/v. the challenge in this scenario is keeping the loop bandwidth wide enough to meet the burst mask at low slope regions which often causes instability at high slope regions. the rf3146a loop bandwidth is determined by internal bandwidth and the rf output load and does not change with respect to power levels. this makes it easier to maintain loop stability with a high bandwidth loop since the bias voltage and collector voltage do not vary. v rampmax 0.4 v batt 0.06 1.5 v + ? = f tot f 1 f 21 ? g 1 --------------- - f 31 ? g 1 g 2 ? ------------------- ++ =
2-503 rf3146a rev a3 051011 an often overlooked prob lem in pa control loops is that a delay not only decreases loop st ability it also affects the burst timing when, for instance the input power from the vco decreases (or increases) with respect to temperature or supply voltage. the burst timing then appears to shift to the right especially at low power levels. the rf3146a is insensitive to a change in input power and the burst timing is constant and requires no software compensation. switching transients occur when the up and down ramp of the burst is not smooth enough or suddenly changes shape. if the control slope of a pa has an inflection point within the output power range or if the slope is simply too steep it is diffi - cult to prevent switching transients. cont rolling the output power by changing the collector volt age is as earlier described based on the physical relationship between voltage swing and output power. furthermore all stages are kept constantly biased so inflection points are nonexistent. harmonics are natural products of high efficiency power amp lifier design. an ideal class ?e? saturated power amplifier will produce a perfect square wave. looki ng at the fourier transform of a square wave reveals high harmonic content. although this is common to all power amplifiers, there are ot her factors that contribute to conducted harmonic content as well. with most power control methods a peak power diode detector is used to rectify and sense forward power. through the rectification process there is additional squaring of the waveform resulting in higher harmonics. the rf3146a address this by eliminating the need for the detector diode. therefore the harmonics coming out of the pa should repre- sent the maximum power of the harmonics throughout the transm it chain. this is based upon proper harmonic termina- tion of the transmit port. the receive port termination on th e t/r switch as well as the harmonic impedance from the switch itself will have an impact on harmonics. should a problem arise, these term inations should be explored. the rf3146a incorporates many circuits that had previously been required external to the power amplifier. the shaded area of the diagram below illustrates those components an d the following table itemiz es a comparison between the rf3146a bill of materials and a conventional solution. component conventional solution rf3146a power control asic $0.80 n/a directional coupler $0.20 n/a buffer $0.05 n/a attenuator $0.05 n/a various passives $0.05 n/a mounting yield (other than pa) $0.12 n/a total $1.27 $0.00 1 2 3 4 5 6 7 14 13 12 11 10 9 8 from dac *shaded area eliminated with indirect closed loop using rf3146
2-504 rf3146a rev a3 051011 pcb design requirements pcb surface finish the pcb surface finish used for rfmd?s qualification process is electroless nickel, immersion gold. typical thickness is 3 inch to 8 inch gold over 180 inch nickel. pcb land pattern recommendation pcb land patterns are based on ipc-sm-782 standards when possible. the pad pattern shown has been developed and tested for optimized assembly at rfmd; however, it may require some modifications to address company specific assembly processes. the pcb land pattern has been developed to accommodate lead and package tolerances. pcb metal land pattern a = 0.64 x 0.28 (mm) typ. b = 0.28 x 0.64 (mm) typ. c = 5.65 (mm) sq. dimensions in mm. pin 36 pin 24 pin 48 pin 1 c b b b b b b b b b b b b b b b b b b b b b b b b a a a a a a a a a a a a a a a a a a a a a a a a 0.50 typ. 0.50 typ. 0.55 typ. 0.55 typ. 5.50 typ. 2.75 5.50 typ. 2.75 figure 1. pcb metal land pattern (top view)
2-505 rf3146a rev a3 051011 pcb solder mask pattern liquid photo-imageable (lpi) solder mask is recommended. th e solder mask footprint will match what is shown for the pcb metal land pattern with a 2mil to 3mil expansion to accommodate solder mask registration clearance around all pads. the center-grounding pad shall also have a solder mask clearance. expansion of the pads to create solder mask clearance can be provided in the master data or requested from the pcb fabrication supplier. thermal pad and via design thermal vias are required in the pcb layout to effectively conduct heat away from the package. the via pattern has been designed to address thermal, power dissipation and electrical requirements of the device as well as accommodating routing strategies. the via pattern used for the rfmd qualification is based on thru-hole vias with 0.203mm to 0.330mm finished hole size on a 0.5mm to 1.2mm grid pattern with 0.025mm plating on via walls. if micro vias are used in a design, it is suggested that the quantity of vias be increased by a 4:1 ratio to achieve similar results. dimensions in mm. pin 36 pin 24 pin 48 pin 1 0.55 typ. 2.75 0.50 typ. 0.55 typ. 5.50 typ. 0.50 typ. 5.50 typ. 1.95 a = 0.74 x 0.38 (mm) typ. b = 0.38 x 0.74 (mm) typ. c = 5.25 x 2.20 (mm) b b b b b b b b b b b b b b b b b b b b b b b b c a a a a a a a a a a a a a a a a a a a a a a a a figure 2. pcb solder mask pattern (top view)
2-506 rf3146a rev a3 051011

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