50 MHz TO 1000 MHz Quadrature Demodulator
The AD8348 is a broadband quadrature demodulator with an integrated intermediate frequency (IF), variable gain amplifier (VGA), and integrated baseband amplifiers. It is suitable for use in communications receivers, performing quadrature demodulation from IF directly to baseband frequencies. The baseband amplifiers are designed to interface directly with dual-channel ADCs, such as the AD9201, AD9283, and AD9218, for digitizing and post-processing.
The IF input signal is fed into two Gilbert cell mixers through an X-AMP® VGA. The IF VGA provides 44 dB of gain control. A precision gain control circuit sets a linear-in-decibel gain characteristic for the VGA and provides temperature compensation. The LO quadrature phase splitter employs a divide-by-2 frequency divider to achieve high quadrature accuracy and amplitude balance over the entire operating frequency range.
The AD8348 is fabricated on an advanced bipolar process, operating on a single 3 or 5 volt supply, packaged in space saving 28 lead thin shrunk small outline (TSSOP) package and fully specified over the –40 to +85 C temperature range
Samples AD8348ARU and evaluation boards AD8348-EVAL are available
Other Modulator/Demodulator products
- AD8345 250MHz – 1GHz RF/IF Modulator
- AD8346 800MHz – 2.5GHz Modulator
- AD8347 800MHz – 2.7GHz Demodulator
- AD8349 700MHz – 2.7GHz Modulator
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AD8348-EVALZ is a fully populated, 4-layer, FR4-based evaluation board designed to allow easy evaluation of all features of the AD8348. The evaluation board integrates a prototype area for a filter design at the mixer outputs, SMA connectors to and from AD8348 with optimized trace routing for improved signal integrity, and requires only a single supply within the range of 2.7 V to 5.5 V.
Recommended Baseband Driver Amplifiers
- For selectable gains of 1, 2 or 3 , we recommend the ADA4950-1 or the ADA4950-2 .
- For a differential RF/IF amplifier , we recommend the ADL5562 or the ADL5565 .
- For a digital programmable VGA , we recommend the AD8366 .
- For low noise drivers in low voltage (1.8V) ADC applications , we recommend the ADA4930-1 or the ADA4930-2 .
- For variable gain and programmable baseband filters , we recommend the ADRF6510 or the ADRF6516 .
Recommended Dual Analog-to-Digital Converters
- For 14-bit performance, low power and high sampling rate , we recommend the AD9258 or the AD9251 .
- For 16-bit performance, low power and high sampling rate , we recommend the AD9268 or the AD9650 .
- For 12-bit performance, low power, low cost and ease of use , we recommend the AD9231 .
- For 16-bit performance, multistage differential pipeline architecture with integrated quadrature error correction (QEC) , we recommend the AD9269 .
- For 16-bit performance, continuous time sigma delta architecture with integrated QEC , we recommend the AD9262 .
Product Selection Guide
RF Source Booklet
RF IC Product Overview
Simplifying Direct-Conversion Tx Paths in Wireless Designs
Optimizing Receiver Performance Through Error Vector Analysis
by Eric Newman, Analog Devices Inc. (Microwave Product Digest, October 2004)