CIRCUIT AND METHOD FOR PROCESSING AFC SIGNALS

摘要

An integrated demodulator tuning circuit (10, 60) receives differential currents at input terminals (12, 46) and provides an AFC signal at an output terminal (48). The AFC current characteristic has a dead band (72) in the output current generated when the integrated demodulator tuning circuit (10, 60) operates under the condition where the difference between the currents supplied at the input terminals (12 and 46) is at or below a set threshold value. The set threshold value is determined by the relative sizes of the transistors (14, 16 and 20, 36, 38 and 40) that form the current mirrors connected to the input terminals (12, 46).