Abstract: A high speed comparator unit for a flash A/D converter in which a bank of comparator units compare simultaneously an analog input voltage with equally spaced reference voltages, and an encoder ROM produces digital signals based on the comparator unit's outputs. The comparator unit includes a two-stage cascode configuration and a level shifter configuration which effectively reduces the miller-effect of the comparator unit.

Abstract: A digital automatic gain control system for maintaining a constant output level through attenuating or amplifying an input signal is disclosed.

Abstract: A FM detection system using a phase locked loop (PPL 20) and including: a wave shaping comparator (7) for accepting a signal V.sub.CO2 from a voltage controlled oscillator (4) which is 90.degree. out of phase with a control signal V.sub.CO1 from the voltage controlled oscillator (4), the comparator reshaping the signal to a square wave; an in-lock detector (8) for accepting the square wave and a frequency modulated input signal (VFM) to provide a sum frequency and a difference frequency; a low-pass filter (9) cutting off the sum frequency component, and filtering out the difference frequency signal when the PLL (20) is unlocked; a comparator (10) for comparing the output of the low-pass filter (9) with a reference voltage (V.sub.