AD6635BBSLASHPCB datasheet(2/60 Pages) AD

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AD6635

GENERAL DESCRIPTION

The AD6635 is a multimode, 8-channel, digital Receive Signal

Processor (RSP) capable of processing up to four WCDMA

channels. Each channel consists of four cascaded signal-process-

ing elements: a frequency translator, two CIC decimating filters,

and a programmable coefficient-decimating filter. Each input

port has input level threshold detection circuitry for accommo-

dating large dynamic ranges or situations where gain ranging

converters are used. Quad 16-bit parallel output ports accom-

modate high data rate WBCDMA applications. On-chip

interpolating half-band filters can also be used to further

increase the output rate. In addition, each output port has a

digital AGC for accommodating large dynamic ranges using

smaller bit widths. The AGCs can maintain either signal level or

clipping level, depending on their mode. Link port outputs are

provided to enable glueless interfaces to Analog Devices’

TigerSHARC DSP core.

The AD6635 is part of Analog Devices’ SoftCell Multicarrier

transceiver chipset designed for compatibility with Analog Devices’

family of high sample rate IF sampling ADCs (AD9238/AD6645

12-bit and 14-bit). The SoftCell receiver comprises a digital

receiver capable of digitizing an entire spectrum of carriers and

digitally selecting the carrier of interest for tuning and channel

selection. This architecture eliminates redundant radios in wireless

base station applications.

High dynamic range decimation filters offer a wide range of

decimation rates. The RAM-based architecture allows easy

reconfiguration for multimode applications.

The decimating filters remove unwanted signals and noise from

the channel of interest. When the channel of interest occupies

less bandwidth than the input signal, this rejection of out-of-band

noise is called “processing gain.” By using large decimation

factors, processing gain can improve the SNR of the ADC by

30 dB or more. In addition, the programmable RAM coefficient

filter allows antialiasing, matched filtering, and static equaliza-

tion functions to be combined in a single, cost-effective filter.

Half-band interpolating filters at the output are used in various

applications, especially in WCDMA or cdma2000 applications,

to increase the output rate from 2

¥ to 4¥ the chip rate. The

AD6635 is equipped with four independent automatic gain

control (AGC) loops for direct interface to a RAKE receiver.

The AD6635 is compatible with standard ADC converters, such

as the AD664x, AD943x, AD923x, and the AD922x families of

data converters. The AD6635 is also compatible with the

AD6600 Diversity ADC, and hence can be designed into exist-

ing systems that use AD6600 ADCs.

AD6635BB/PCB Datasheet(PDF) 2 Page - Analog Devices

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