Gsm 3 V Transceiver If Subsystem - Analog Devices

The AD6432 IF IC provides the complete transmit and receive IF signal processing, including I/Q modulation and demodula- tion, necessary to implement a digital Wireless transceiver such as a GSM handset. The AD6432 may also be used for other Wireless TDMA standards using I/Q modulation. The AD6432s receive signal path is based on the proven archi- tecture of the AD607 and the AD6459. It consists of a mixer, gain-controlled Amplifiers integrated roofing Filter and I/Q Demodulators based on a PLL The low noise, high-intercept variable-gain mixer is a doubly-balanced Gilbert-cell type. It has a nominal 13 dBm input-referred 1 dB compression point and a 0 dBm input-referred third-order intercept. The gain-control input accepts an external control voltage input from an external AGC detector or a DAC It provides an 80 dB gain range with 27.5 mV/dB gain scaling, where the mixer and the IF gains vary together. The I and Q Demodulators provide inphase and quadrature baseband outputs to Interface with Analog Devices AD7015 and AD6421 (GSM, DCS1800, PCS1900) baseband convert- ers. An onboard quadrature VCO externally phase-locked to the IF signal, drives the I and Q Demodulators The quadrature phase-locked Oscillator (QPLO) requires no external compo- nents for frequency control or quadrature generation, and de- modulates signals at standard GSM system IFs of 13 MHz, or 26 MHz with a reference input frequency of 13 MHz; or, in general, 1X or 2X the reference frequency. Maximum reference frequency is 25 MHz. By Analog Devices, Inc.