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Preliminary
S518324-44Z
UPSTREAM CATV AMPLIFIER
FEATURES
* SINGLE 3.3 V SUPPLY OPERATION * LOW POWER CONSUMPTION: 143 mA typical * 63 dB DYNAMIC RANGE: -2.5 to 61 dBmV output * EXCELLENT LINEARITY 2nd/3rd Harmonics >60 dBc typical * PROGRAMMABLE GAIN IN 0.5 dB STEPS * ULTRA LOW ON/OFF TRANSIENTS * DOCSIS 2.0 Plus and RoHS compliant
FUNCTIONAL DIAGRAM
DESCRIPTION
The S518324 is a high performance, CMOS, low power programmable power amplifier designed for use in CATV upstream applications. The amplifier operates over a frequency range from 5 to 65 MHz and has a maximum output of 61 dBmV. A 3-wire serial interface controls the gain over a 63.5 dB range in 0.5 dB steps. The S518324 is available in a thermally enhanced QFN20 4x4 .The product is DOCSIS and RoHS compliant.
APPLICATIONS
* * * * Set-Top Boxes Cable Telephony Cable Modems CATV Infrastructure
RF ELECTRICAL CHARACTERISTICS(TA = 25C, VDD = 3.3 V, unless otherwise specified)
SYMBOLS RF Performance AV AV Gain FIN = 5 MHz, Gain Code = 127 Gain FIN = 65 MHz, Gain Code = 127 Gain Flatness, FIN = 5 to 42 MHz Gain Flatness, FIN = 5 to 65 MHz Attenuation Range, Gain Code = 0 to 127 Attenuation Step Size, Gain Code = 0 to 127 Output Return Loss, 5 to 65 MHz Isolation, 5 to 65 MHz, TXEN = 0 (Transmit Disable Mode) Transmit Mode Noise, 5 to 65 MHz, BW = 160 KHz, Gain Code = 127 to 96 Transmit Mode Noise, 5 to 65 MHz, BW = 160 KHz, Gain Code = 95 to 32 Transmit Mode Noise, 5 to 65 MHz, BW = 160 KHz, Gain Code = 31 to 0 Transmit Disable Mode Noise, 5 to 65 MHz, BW = 160 KHz, TXEN = 0 2nd Harmonic Distortion, VOUT = 60 dBmV, 5 to 65 MHz 3rd Harmonic Distortion, VOUT = 60 dBmV, 5 to 65 MHz dB dB dB dB dB dB dB dB dBmV dBmV dBmV dBmV dBc dBc 26 25.2 31 28 1.75 3.0 63.5 0.5 15 -90 -30 -45 -52 -68 60 58 PARAMETERS UNITS MIN TYP MAX
2 3.5
10
-28 -43 -50
HD2 HD3
Performance tests and ratings for RFMDs' products were performed internally by RFMD and measured using specific computer systems and/or components and reflect the approximate performance of the products as measured by those tests. Any difference in circuit implementation, test software, or test equipment may affect actual performance. The information provided herein is believed to be reliable at press time and RFMDs assumes no responsibility for the use of this information. All such use shall be entirely at the user's own risk. Prices and specifications for RFMDs' products are subject to change without notice. Buyers should consult RFMDs' standard terms and conditions of sale for RFMD's limited warranty with regard to its products. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. RFMDs does not authorize or warrant any product for use in life-support devices and/or systems.
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 1
REV.9
6/19/2008 EDS-105590
Preliminary
S518324-44Z DC ELECTRICAL CHARACTERISTICS
SYMBOLS DC Performance Supply Voltage Supply Current Gain Code = 127 TXEN =1, D7 = 0,SLEEP = 1 Gain Code = 63 to 0 IDD Supply Current, TXEN = 0, D7 = 0, SLEEP = 1 IDD Supply Current, D7 =1 or SLEEP=0 Logic Inputs VINH Input High Voltage VINL Input Low Voltage VDD IDD V mA mA mA uA V V 3.2 3.3 143 70 30 3.5 160 PARAMETERS UNITS MIN TYP MAX
10 VDD -0.4 0.4
ABSOLUTE MAXIMUM RATINGS
(TC = 25C unless otherwise noted) SYMBOLS VDD TOP TSTG Tjmax PARAMETERS Supply Voltage Operating Temperature Storage Temperature Junction Temperature UNITS V C C C RATINGS -0.3 to +3.6 -40 to +85 -65 to 150 150
PIN ASSIGNMENTS
ojc Thermal Resistance C/W 34 Note: 1. Operation in excess of any one of these parameters may result in permanent damage.
PIN FUNCTIONS
QFN 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 PIN NAME GND GND VIN+ VINGND LE D ATA C LK GND S LE E P NC TERM VOUTVOUT+ RAMP TXEN VC C GND GND VC C D ESC RIPTION Ground Ground Posi ti ve i nput. Negati ve i nput. Ground Seri al Interface Enable. TTL compati ble i nput. See Seri al Interface secti on. Seri al Interface D ata. TTL compati ble i nput. See Seri al Interface secti on Seri al Interface C lock. TTL compati ble i nput. See Seri al Interface secti on Ground Hardware Shutdown. For fast shutdown, TXEN must be low when SLEEP i s set low. No C onnect A resi stor of 60ohms and a bypass cap must be connected i n seri es to the output of the transformer to ensure proper output i mpedance when output-amp i s di sable. Negati ve output of the output-amp stage. Along wi th VOUT+, the two ports form a di fferenti al i mpedance of 75 ohms. Posi ti ve output of the output-amp stage. Along wi th VOUT-, the two ports form a di fferenti al i mpedance of 75 ohms. An external capaci tor to ground i s connected to control the ramp-up and ramp-down duri ng transmi t enable and di sable. Transmi t enable. D ri ve TXEN hi gh to turn on the output stage. 3.3V Ground Ground 3.3V
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 2
REV.9
6/19/2008 EDS-105590
Preliminary
TYPICAL PERFORMANCE CURVES
VOLTAGE GAIN vs. GAIN CODE
40 30
S518324-44Z
TRANSMIT NOISE vs. GAIN CODE
Output Noise (dBmV in 160 KHz)
-25 -30 -35 -40 -45 -50 -55 -60 7MHz 43MHz
Voltage Gain (dB)
20 10 0 -10 -20 -30 -40 0 20 40 60 80 100 120 7MHz 43MHz
0
20
40
60
80
100
120
Gain Code
Gain Code 3RD HARMONIC vs. GAIN CODE (POUT = 60dBmV @ GCW = 127)
-40 -45
2ND HARMONIC vs. GAIN CODE (POUT=60dBmV @ GCW=127)
-40 -45
-55 -60 -65 -70 -75 -80 -85 -90 50 60 70 80 90 100 110 120
7MHz 43MHz
3rd Harmonic (dBc)
-50 2nd Harmonic (dBc)
-50 -55 -60 -65 -70 -75 -80 -85 -90 50 60 70 80 90 100 110 120
7MHz 43MHz
Gain Code
(
)
Gain Code
SUPPLY CURRENT vs. GAIN CODE
150 140
Supply Current (mA)
130 120 110 100 90 80 70 60 50 0 20 40 60 80 100 120
Gain Code
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 3
REV.9
6/19/2008 EDS-105590
Preliminary
FUNCTIONAL DESCRIPTION
Upstream CATV Amplifier The upstream CATV amplifier consists of an input attenuator (ATTN1), pre-amp, intermediate attenuator (ATTN2), power amp, serial data interface, bias control, ramp generator, and a switch. The amplifier and the attenuator blocks are capable of providing a gain range of 63.5 dB with 0.5 dB steps across the specified frequencies of operation. The gain and current of the whole chain is determined by a 7 bit word programmed using the serial data interface. Input Interface The differential input impedance of the upstream CATV amplifier is 150 ohms. The input anti-aliasing filter should be designed to the same impedance for proper operation. The output impedance of the DAC should also be set accordingly. In order to achieve the specified performance, the inputs should be driven differentially. Output Interface The differential output impedance of the upstream CATV amplifier is 75 ohms provided that the suggested value of the shunt feedback resistor of the power amp stage is used. The differential output is converted to a single-ended output with a 1:1 turn ratio transformer. Switch During transmit disable mode, the 75 ohm output impedance is maintained by switching in a shunt 60 ohm resistor connected from the single-ended output of the transformer to Pin 12. The switch is toggled by the TXen pin, SLEEP pin, and D7 bit. When TXEN and SLEEP are high and D7 = 0 (transmit mode), the switch is open. It is closed when TXEN or SLEEP is low or D7 = 1.
S518324-44Z
Power Amp (PA) The power amplifier stage is a Class A differential amplifier with shunt feedback and series feedback. It is capable of providing an output level of 61 dBmV. The 3.3 V bias of the PA stage comes from the center-tap of the 1:1 turn ratio transformer. The transformer will suppress the even-order distortion and the transients caused by enabling and disabling the PA. Ramp Generator This block is a simple RC charging circuit consisting of an internal 1K ohm resistor and an external capacitor Cext. This circuit controls the ramp up and down time of the PA stage during bursts. Bias Control The bias control sets the current of the PA stage at various gain states. In the lower gain states, the current of the PA is reduced and overall power consumption decreases. Serial Interface The serial interface becomes active when LE (latch enable) is low. The overall gain, current, and chip shutdown are determined by the programming of the bits D0 - D7. See Table 1, Table 2, Table 3, and Serial-Interface Timing Diagram for programming details. For fast shutdown, TXEN must be low when D7 is set low.
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 4
REV.9
6/19/2008 EDS-105590
Preliminary
FUNCTIONAL DESCRIPTION (CON'T)
Table 1. Attenuator States
TXen 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 SLEEP 0 1 X 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 D7 X X 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 D6 X X X 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 D5 X X X 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 0 D4 X X X 1 1 1 0 0 1 1 1 0 1 1 0 0 1 1 1 0 0 D3 X X X 1 1 1 0 0 1 1 0 0 1 1 1 0 1 1 0 0 0 D2 X X X 1 1 0 1 0 1 1 0 0 1 1 0 0 1 1 1 0 0 D1 X X X 1 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 D0 X X X 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 Gain Code (Decimal) X X X 127 125 121 101 97 95 93 81 65 63 61 41 33 31 29 21 1 0
S518324-44Z
State Shutdown Transmit Disable Shutdown Av = 30.0 dB Av = 29.0 dB Av = 27.0 dB Av = 17.0 dB Av = 15.0 dB Av = 14.0 dB Av = 13.0 dB Av = 7.0 dB Av = -1.0 dB Av = -2.0 dB Av = -3.0 dB Av = -13.0 dB Av = -17.0 dB Av = -18.0 dB Av = -19.0 dB Av = -23.0 dB Av = -33.0 dB Av = -33.5 dB
Table 2. Attenuator Values
BIT D0 D1 D2 D3 D4 D5 D6 ATTENUATION (dB) 0.5 1.0 2.0 4.0 8.0 16.0 32.0
Table 3. Serial-Interface Control Word
BIT MSB 7 6 5 4 3 2 1 LSB 0 MNEMONIC D7 D6 D5 D4 D3 D2 D1 D0 DESCRIPTION Shutdown (TXEN = 0) Gain Control, Bit 6 Gain Control, Bit 5 Gain Control, Bit 4 Gain Control, Bit 3 Gain Control, Bit 2 Gain Control, Bit 1 Gain Control, Bit 0
Serial-Interface Timing Diagram
A G B C D E F
LE CLK DATA D7 D6 D5 D4 D3 D2 D1 D0
A. t SENS B. t SDAS C. t SDAH D. t SCKL
E. t SCKH F. t SENH G. t DATAH /t DATAL
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 5
REV.9
6/19/2008 EDS-105590
Preliminary
TYPICAL APPLICATION CIRCUIT
S518324-44Z
PACKAGE INFORMATION QFN 20 (Units in mm)
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 6
REV.9
6/19/2008 EDS-105590
Preliminary Evaluation Board Schematic
TX_EN
S518324-44Z
3.3V
R4 1k C20 .01uF
GND GND 19 GND GND 18 17 16 3.3V
C21 .01uF
R14 0
GND
C14 1000pF
VCC
20
GND
GND
VCC
TXEN
C1
15 GND
GND
GND
1 2 3
GND GND TXin+ TXinGND
RAM P
J3
3 2 1 GND GND
R9 24 R12 NL
C12 .01uF
4
T1
C2 2.2pF
3
C4 GND .01uF R13 NL
GND
U1 S518324-44Z
1000pF
Vout+ Vout TERM NC SLEEP 14 13 GND 12 11
1
T1
6 GND GND
C10
2
.01uF
3
-4.77dB
GND
R8 75
GND 6
C11 TOKO 1:1
4
4 5
2
DATEN
SDA TA
GND
GND
CLK
1
TOKO 1:1
GND TOK Footpri O nt
6
7
8
9
10
C5 .01uF R16 0 C16 R17 NL 1k
GND
GND GND
GND
JP2
GND 3.3V TX_L E DA CK TX_S H TX_E N 1 2 3 4 5 6
R15 0 R20 0 R21 1k
C15 1000pF R2 0
TX_SH
3.3V
C13 NL
R3 75
C9 .01uF
R6 .01uF 43 R7 43
R22 NL
J1
GND 1 2 GND 3
-4.77dB R11 43
GND
R18 0 C17 NL
GND
R19 1k
DA
C18 NL
7PIN
PACKAGE INFORMATION (CON'T)
1.
2. 3.
Dimensions and tolerances conform to ASME Y14.5-1994. All dimensions are in millimeters. All angles are in degrees. The exposed thermal pad is also an electrical ground .
LAND PATTERN FOR TERMINALS AND THERMAL/GROUND PAD
TX_LE
DATA SUBJECT TO CHANGE WITHOUT NOTICE
7628 Thorndike Road, Greensboro, NC 27409-9421 For sales or technical support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com 7
CK
7
GND
REV.9
6/19/2008 EDS-105590

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