AD6657A Datasheet, PDF (1/36 Pages) Analog Devices – Quad IF Receiver

Data Sheet
FEATURES
11-bit, 200 MSPS output data rate per channel
Integrated noise shaping requantizer
Performance with NSR enabled
SNR: 76.0 dBFS in 40 MHz band to 70 MHz at 185 MSPS
SNR: 73.6 dBFS in 60 MHz band to 70 MHz at 185 MSPS
SNR: 72.8 dBFS in 65 MHz band to 70 MHz at 185 MSPS
Performance with NSR disabled
SNR: 66.5 dBFS to 70 MHz at 185 MSPS
SFDR: 88 dBc to 70 MHz at 185 MSPS
Low power: 1.2 W at 185 MSPS
1.8 V analog supply operation
1.8 V LVDS (ANSI-644 levels) output
1-to-8 integer clock divider
Internal ADC voltage reference
1.75 V p-p analog input range (programmable to 2.0 V p-p)
Differential analog inputs with 800 MHz bandwidth
95 dB channel isolation/crosstalk
Serial port control
User-configurable built-in self test (BIST) capability
Energy saving power-down modes
APPLICATIONS
Communications
Diversity radio and smart antenna (MIMO) systems
Multimode digital receivers (3G)
WCDMA, LTE, CDMA2000
WiMAX, TD-SCDMA
I/Q demodulation systems
General-purpose software radios
GENERAL DESCRIPTION
The AD6657A is an 11-bit, 200 MSPS, quad channel intermediate
frequency (IF) receiver specifically designed to support multiple
antenna systems in telecommunication applications where high
dynamic range performance, low power, and small size are desired.
The device consists of four high performance ADCs and NSR
digital blocks. Each ADC consists of a multistage, differential
pipelined architecture with integrated output error correction
logic. The ADC features a wide bandwidth switched capacitor
sampling network within the first stage of the differential pipeline.
An integrated voltage reference eases design considerations. A
duty cycle stabilizer (DCS) compensates for variations in the
ADC clock duty cycle, allowing the converters to maintain
excellent performance.
Rev. 0
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Quad IF Receiver
AD6657A
FUNCTIONAL BLOCK DIAGRAM
AVDD AGND DRVDD DRGND
VIN+A
VIN–A
VCMA
VIN+B
VIN–B
VCMB
VIN+C
VIN–C
VCMC
VIN+D
VIN–D
VCMD
AD6657A
14
11
PIPELINE
NOISE SHAPING
ADC
REQUANTIZER
PIPELINE ¹⁴ NOISE SHAPING ¹¹
ADC
REQUANTIZER
PIPELINE ¹⁴ NOISE SHAPING ¹¹
ADC
REQUANTIZER
14
11
PIPELINE
NOISE SHAPING
ADC
REQUANTIZER
DCO±AB
DO±AB
PORT A
D10±AB
DCO±CD
DO±CD
PORT B
D10±CD
REFERENCE
SERIAL PORT
CLOCK
DIVIDER
MODE
SYNC
PDWN
SCLK SDIO CSB
Figure 1.
CLK+ CLK–
Each ADC output is connected internally to an NSR block. The
integrated NSR circuitry allows for improved SNR performance
in a smaller frequency band within the Nyquist bandwidth. The
device supports two different output modes selectable via the
external MODE pin or the serial port interface (SPI).
With the NSR feature enabled, the outputs of the ADCs are
processed such that the AD6657A supports enhanced SNR per-
formance within a limited portion of the Nyquist bandwidth
while maintaining an 11-bit output resolution. The NSR block
can be programmed to provide a bandwidth of either 22%, 33%,
or 36% of the sample clock. For example, with a sample clock
rate of 185 MSPS, the AD6657A can achieve up to 76.0 dBFS
SNR for a 40 MHz bandwidth in the 22% mode, up to 73.6 dBFS
SNR for a 60 MHz bandwidth in the 33% mode, or up to 72.8 dBFS
SNR for a 65 MHz bandwidth in the 36% mode.
(General Description continued on Page 3)
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