AD9874BST AD [Analog Devices], AD9874BST Datasheet

AD9874BST

Manufacturer Part Number

AD9874BST

Description

IF Digitizing Subsystem

Manufacturer

AD [Analog Devices]

Datasheet

1.AD9874BST.pdf (40 pages)

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*Protected by U.S. Patent No. 5,969,657; other patents pending.

REV. 0

Information furnished by Analog Devices is believed to be accurate and

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

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

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

under any patent or patent rights of Analog Devices.

FEATURES

10 MHz–300 MHz Input Frequency

6.8 kHz–270 kHz Output Signal Bandwidth

8.1 dB SSB NF

0 dBm IIP3

AGC Free Range up to –34 dBm

12 dB Continuous AGC Range

16 dB Front End Attenuator

Baseband I/Q 16-bit (or 24-bit) Serial Digital Output

LO and Sampling Clock Synthesizers

Programmable Decimation Factor, Output Format,

370

2.7 V–3.6 V Supply Voltage

Low Current Consumption: 20 mA

48–Lead LQFP Package (1.4 mm Thick)

APPLICATIONS

Multimode Narrowband Radio Products

Portable and Mobile Radio Products

Base Station Applications

AGC, and Synthesizer Settings

Analog/Digital UHF/VHF FDMA Receivers

TETRA, APCO25, GSM/EDGE

Input Impedance

FREF

IFIN

IOUTL

SYNC

–16dB

LNA

LOOP FILTER

LO VCO AND

LOP

MXOP MXON IF2P IF2N

LON

IOUTC

FUNCTIONAL BLOCK DIAGRAM

SAMPLE CLOCK

SYNTHESIZER

LOOP FILTER

LO VCO AND

CLKP

GCP GCN

- ADC

CLKN

DAC

VREFP

GENERAL DESCRIPTION

The AD9874 is a general-purpose IF subsystem that digitizes a

low level 10 MHz–300 MHz IF input with a signal bandwidth

ranging from 6.8 kHz to 270 kHz. The signal chain of the AD9874

consists of a low noise amplifier, a mixer, a band-pass sigma-delta

analog-to-digital converter, and a decimation filter with program-

mable decimation factor. An automatic gain control (AGC) circuit

gives the AD9874 12 dB of continuous gain adjustment. Auxiliary

blocks include both clock and LO synthesizers.

The AD9874’s high dynamic range and inherent antialiasing

provided by the band-pass sigma-delta converter allow the

AD9874 to cope with blocking signals up to 95 dB stronger

than the desired signal. This attribute can often reduce the cost of

a radio by reducing its IF filtering requirements. Also, it enables

multimode radios of varying channel bandwidths, allowing the

IF filter to be specified for the largest channel bandwidth.

The SPI port programs numerous parameters of the AD9874,

thus allowing the device to be optimized for any given

application. Programmable parameters include the following:

synthesizer divide ratios; AGC attenuation and attack/decay

time; the received signal strength level; decimation factor; the

output data format; 16 dB attenuator; and the selected bias

currents. The bias currents of the LNA and mixer can be further

reduced at the expense of the degraded performance for battery-

powered applications.

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

Tel: 781/329-4700

Fax: 781/326-8703

REFERENCE

VOLTAGE

DECIMATION

AGC

VCM

FILTER

VREFN

CONTROL LOGIC

IF Digitizing Subsystem

FORMATTING/SSI

SPI

AD9874

SYNCB

DOUTA

DOUTB

CLKOUT

AD9874

www.analog.com

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