Patent ID: 6791371
Filing Date: 2004-09-14
Classification: H03K

Abstract:
A differential equal-voltage detector comprising:a differential input including a true differential input and a complement differential input, the true and complement differential inputs being driven to opposite states during normal operation, but the true and complement differential inputs being equalized to an equal voltage when an input-failure occurs; a multiplier, receiving the true and complement differential inputs, for squaring a voltage difference between the true and complement differential inputs to generate a squared voltage; a low-pass filter, coupled to the multiplier, for filtering the squared voltage to smooth variations in the squared voltage to generate an averaged voltage; and a comparator, coupled to receive the averaged voltage, for comparing the averaged voltage to a reference voltage, and for activating a detect signal when the averaged voltage is below the reference voltage, whereby the detect signal is activated when the voltage difference is below a threshold to signal the input-failure.