24 dB Gain
4 dB Noise Figure
Easy Match to SAW Filters
Output Limiter Adjustable +8.5 dBm to +12 dBm
700 MHz Bandwidth
10 V Single or Dual 5 V Power Supply
300 mW Power Dissipation
ADC IF Drive Amp
PCS/Cellular Base Stations
GSM, CDMA, TDMA
Differential, Low Noise IF Gain
Block with Output Clamping
FUNCTIONAL BLOCK DIAGRAM
NC = NO CONNECT
The AD6630 is an IF gain block designed to interface between
SAW filters and differential input analog-to-digital converters.
The AD6630 has a fixed gain of 24 dB and has been optimized
for use with the AD6600 and AD6620 in digitizing narrowband
IF carriers in the 70 MHz to 250 MHz range.
Taking advantage of the differential nature of SAW filters, the
AD6630 has been designed as a differential in/differential out
gain block. This architecture allows 100 dB of adjacent channel
blocking using low cost SAW filters. The AD6630 provides
output limiting for ADC and SAW protection with Ͻ10° phase
variation in recovery from overdrive situations.
Designed for “narrow-band” cellular/PCS receivers, the high
linearity and low noise performance of the AD6630 allows for
implementation in a wide range of applications ranging from
GSM to CDMA to AMPS. The clamping circuitry also main-
tains the phase integrity of an overdriven signal. This allows
phase demodulation of single carrier signals with an overrange
While the AD6630 is optimized for use with the AD6600 Dual
Channel, Gain Ranging ADC with RSSI, it can also be used in
many other IF applications. The AD6630 is designed with an
input impedance of 200 Ω and an output of 400 Ω. In the typi-
cal application shown below, these values match the real portion
of a typical SAW filter. Other devices can be matched using
standard matching network techniques.
The AD6630 is built using Analog Devices’ high speed comple-
mentary bipolar process. Units are available in a 300 mil SOIC
(16 leads) plastic surface mount package and specified to operate
over the industrial temperature range (–40°C to +85°C).
AD6600 AD6620 DSP
Figure 1. Reference Design
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