A signal amplitude comparator which includes a first input that receives an input signal and generates an output signal that is a non-linear function of the input signal, and a second input circuit that receives a reference input signal and generates a second output signal that generally tracks process, temperature and supply variation. The signal amplitude comparator also includes an amplifier, a filter and a comparator. The amplifier amplifies a signal difference between the first and second output signals and outputs a train of pulses if a peak of the input signal exceeds the reference input signal. A second reference signal is applied to the comparator which generates an output which indicates whether the input signal exceeds a pre-determined threshold value. The signal amplitude comparator also includes a pair of input amplifiers which receive and translate the input and reference input signals to levels suitable for the input circuits.
RELATED APPLICATION (PRIORITY CLAIM)
The present application is a continuation-in-part of U.S. patent application Ser. No. 10/156,963, filed May 29, 2002 now U.S. Pat. No. 6,617,889.
A peak voltage detector is used to detect the absolute value of the peak differential amplitude of a differential input signal. The peak voltage detector includes a differential amplifier receiving the differential input signal and generating a corresponding pair of differential output signals. The voltage detector also includes a capacitor on which an output signal is generated. A first differential comparator generates a first signal whenever the differential voltage from the differential amplifier is greater than the voltage of the output signal. A second differential comparator generates a second signal whenever the negative of the differential voltage from the differential amplifier is greater than the voltage of the output signal. A current source applies current to the capacitor responsive to receiving either the first or second signal. The amplitude of the feedback voltage is thus equal to the absolute value of the peak differential amplitude of the input signal.
