ANALOG DEVICES AD6600, AD6620 Service Manual
AD6600/AD6620
Diversity Receiver Chipset
HIGHLY INTEGRATED CHIPSET
REDUCES SIZE AND COST OF BASE
STATION RECEIVERS
Analog Devices’ innovative Diversity Receiver
chipset delivers two IF-to-baseband diversity
channels in a compact, comprehensive solution
that incorporates Automatic Gain Control,
Received Signal Strength Indicator, highresolution Numerically Controlled Oscillator
and digital filtering on-chip.
The chipset comprises Analog Devices’ AD6600
dual-channel IF sampling analog-to-digital
converter and AD6620 dual-channel decimating
receiver chip. Configured with the appropriate
external components, it can address a variety of
air interface standards, including GSM, CDMA,
IS136 and PHS, as well as proprietary modulation schemes for paging systems and wireless
fixed access receivers.
Based on Analog Devices’ next-generation
receiver architecture, the Diversity Receiver
replaces sensitive analog filters with digital
filters for significant cost and size reductions.
Complete reference designs show the optimal
layout for reducing noise and minimizing
cross-channel coupling.
Analog Devices’
streamlined, highly
integrated solution
reduces component
count, cost and
time-to-market for
diversity receivers.
FEATURES
• Dual-channel: integrates two IF-to-baseband diversity channels
• Fewer discrete components: cuts manufacturing costs
• On-chip digital filters eliminate need for high-cost analog IF filter for
reduced bill of materials cost
• Accepts common intermediate frequencies for cellular, PCS, paging
(70-250 MHz Ain)
• Small outline, surface-mount plastic packaging (44-pin TQFP, 80-pin
PQFP): reduces receiver size, simplifies micro- and pico-cell designs
• High dynamic range: 80 to 100+ dB, depending on channel bandwidth,
sample rate and filter characteristics
• Easily interfaces to general-purpose DSPs
• Complete radio reference designs reduce your engineering investment
RF
Synthesizer
BPF
BPF BPF
Digital
Filter
DSP
BSC
or
MSC
BPF
BPF BPF
AGC,
Sampler,
RSSI
AD6600 AD6620
Diversity
Input
Main Input
70 - 250 MHz IF
Main
Diversity
SAW
SAW
The most demanding filtering takes place in the digital
signal processor, dramatically
reducing the burden on the
front-end analog IF filter.
Characteristics for bandwidth,
passband ripple and stopband
rejection are specified through
software, not through sensitive
and costly surface acoustical
wave (SAW), crystal and ceramic devices. You get the filtering
precision you need — in a more
easily manufactured solution.
HIGH DYNAMIC RANGE
Automatic gain control through
a built-in peak detector ensures
optimum receiver sensitivity.
This unique feature enables the
AD6600 to perform its own
automatic gain ranging on a
sample-by-sample basis.
The AD6600 provides 90 dB
of instantaneous dynamic range;
the AD6620 yields an additional
12-25 dB of processing gain,
depending on bandwidth and
sample rate.
ANALOG DEVICES: LEADING
BASE STATION SUPPLIER
At the forefront of nextgeneration receiver technology,
Analog Devices is an established
supplier of integrated circuits
used in current cellular base station subsystem designs.
We have the largest market
share of mixed-signal integrated
circuits in base stations worldwide. And we also hold a leadership position in high-speed
conversion technology and high
dynamic range sampling.
ANALOG DEVICES IN
COMMUNICATIONS
Analog Devices is committed to
supplying the communications
industry with the highestperformance solutions at the
lowest possible cost. We meet
the needs of today’s broadband
wired and wireless markets with
leadership capabilities in analog,
digital and mixed signal processing, RF signal processing, data
conversion, interfaces and total
system design.
DIVERSITY RECEIVER
CHIPSET
Analog Devices’ Diversity
Receiver chipset consists of:
• AD6600 dual-channel IF
sampling ADC chip
The AD6600 is a mixed-signal
receive chip designed to
directly sample IF signals at
frequencies up to 250 MHz A
in
.
The chip includes an 11-bit
20 MSPS ADC, input amplifiers, automatic gain ranging
circuitry, 450 MHz Track/Hold,
digital RSSI outputs, references and control circuitry.
Digital signals are CMOS/TTL
compatible.
Each of its two analog input
channels (A and B) has its
own attenuator stage.
Attenuation levels are set by
the on-chip automatic RSSI
circuitry.
Units are packaged in a 44-pin
Thin Quad Plastic Flatpack
(TQFP).
• AD6620 dual-channel
decimating receiver chip
The AD6620 is a dual-channel
65 MSPS decimating receiver
that maintains a spurious free
dynamic range (SFDR) greater
than 100 dB. Its four cascaded
signal processing elements are
a digital tuner, two fixed coefficient filters and a programmable coefficient decimating filter.
The AD6620’s RAM-based
architecture enables antialiasing, matched filtering and
static equalization functions to
be combined in a single chip.
Units are packaged in an 80-pin
Plastic Quad Flatpack (PQFP).
REFERENCE DESIGNS
AD6600/AD6620 Diversity
Receiver reference designs
indicate all required external
components in the optimal
PCB layout that minimizes
cross-channel coupling for the
lowest possible noise interference. Designs, along with a
complete set of application
notes and technical white
papers, are available for individual air interface standards.
COST-SAVING INNOVATIVE
DESIGN
Analog Devices’ advanced
receiver architecture lets you
take advantage of tight on-chip
integration of conversion and
filtering functions for a highperformance diversity radio.
This innovative approach
eliminates front-end mix-down
stages and enables highfrequency IF sampling at
70–250 MHz.
Specifically designed for
narrowband cellular/PCS
receivers, the Diversity Receiver
is ideal for applications such as
GSM and CDMA, where multiple
calls are processed in a single
RF channel.
In this dual-channel design,
analog RF filters are replaced by
digital filters that are more easily manufactured and assembled,
require no factory “tweaking”
and do not vary in performance
over time or as a result of temperature changes.
The bottom line: lower
manufacturing and bill of materials costs — as well as reduced
inventory requirements.
CUTS TIME-TO-MARKET
Analog Devices offers a complete solution and full support
for diversity radios.
Because the same core
components can be used for
different air interface standards,
you can bring base station
equipment to market quickly
and cost-effectively. With minimal design change, your base
station receiver can readily
accommodate different air
interface standards.
Analog Devices’ support
services — including detailed
reference designs using the
AD6600/AD6620 chipset — help
streamline your development
efforts.
DIGITAL COMPONENTS
OPTIMIZE SYSTEM
PERFORMANCE
By reducing the number of
analog RF components, the
AD6600/AD6620 Diversity
Receiver optimizes the performance of your base station
radio.
IF Sampling Diversity Receiver
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