Dual Channel, Gain-Ranging
ADC with RSSI
Dual IF Inputs, 70 MHz–250 MHz
Diversity or Two Independent IF Signals
Separate Attenuation Paths
Oversample RF Channels
20 MSPS on a Single Carrier
10 MSPS/Channel in Diversity Mode
Total Signal Range 90+ dB
30 dB from Automatic Gain-Ranging (AGC)
60 dB from A/D Converter
Range >100 dB After Processing Gain
11-Bit ADC Word
3-Bit RSSI Word
2؋ Clock, A/B Indicator
Single 5 V Power Supply
Output DVCC 3.3 V or 5 V
775 mW Power Dissipation
PCS/Cellular Base Stations
GSM, CDMA, TDMA
Wireless Local Loop, Fixed Access
The AD6600 mixed-signal receiver chip directly samples signals
at analog input frequencies up to 250 MHz. The device includes
two input channels, each with 1 GHz input amplifiers and
30 dB of automatic gain-ranging circuitry. Both channels are
sampled with a 450 MHz track-and-hold followed by an 11-bit,
20 MSPS analog-to-digital converter. Digital RSSI outputs, an
A/B channel indicator, a 2× Clock output, references, and con-
trol circuitry are all on-chip. Digital output signals are two’s
complement, CMOS-compatible and interface directly to
3.3 V or 5 V digital processing chips.
The primary use for the dual analog input structure is sampling
both antennas in a two-antenna diversity receiver. However,
Channels A and B may also be used to sample two independent
IF signals. Diversity, or dual-channel mode, is limited to 10 MSPS
per channel. In single-channel mode, the full clock rate of
20 MSPS may be applied to a single carrier.
The AD6600 may be used as a stand-alone sampling chip, or it
may be combined with the AD6620 Digital Receive Signal Pro-
cessor. The AD6620 provides 10 dB–25 dB of additional pro-
cessing gain before passing data to a fixed- or floating-point DSP.
Driving the AD6600 is simplified by using the AD6630 differen-
tial IF amplifier. The AD6630 is easily matched to inexpensive
SAW filters from 70 MHz to 250 MHz.
Designed specifically for cellular/PCS receivers, the AD6600
supports GSM, IS-136, CDMA and Wireless LANs, as well as
proprietary air interfaces used in WLL/fixed-access systems.
Units are available in plastic, surface-mount packages (44-lead
LQFP) and specified over the industrial temperature range
(–40°C to +85°C).
FUNCTIONAL BLOCK DIAGRAM
0dB, –12dB, –24dB
0dB, –12dB, –24dB
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