Modulation Imperfections in IS54 Dual Mode Cellular Radio

Non ideal I and Q calibration circuits on one hand, phase noise spurious response of the synthesizers and carrier leakage on the other hand, will affect the modulation quality by degrading Modulation parameters such as EVM, Spectral Mask and Residual AM. Transmitter's gain chain and its output power amplifier linearity and synthesizers phase noise will degrade the spectral purity of the transmitter and its Spectral Mask even further, consequently degrade system's performance - Bit Error Rate (BER). This presentation will identify typical Modulation errors related to the RF and Digital sections of the Dual Mode[12,13] (TDMA/AMPS) Cellular phone front end, and develop calibration methods which will effectively minimize the modulator intemal errors by analyzing the output signal. We will focus on π/4DQPSK digital modulation imperfections, errors in synthetic base band I & Q signals used to generate FM modulated signal by a QPSK modulator, Non linear effects and a modulation scheme commonly used in cellular IS54 radios