REV. 0

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reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

AD6630

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 1998

Differential, Low Noise IF Gain

Block with Output Clamping

FUNCTIONAL BLOCK DIAGRAM

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

NC = NO CONNECT

NC

AD6630

NC

IP2

IP1

IP1

IP2

CLLO

CLHI

CD1

OP

CMD

OP

CD2

+

+

+

FEATURES

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

APPLICATIONS

ADC IF Drive Amp

Communications Receivers

PCS/Cellular Base Stations

GSM, CDMA, TDMA

PRODUCT DESCRIPTION

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

10

° 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

signal.

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).

LOCAL

OSCILLATOR

AD6630

AD6620

DSP

MAIN

DIVERSITY

AD6600

AD6630

AD6620

Figure 1. Reference Design