Squelch circuit to create a squelch waveform for USB 2.0

Abstract

Disclosed is a squelch circuit capable of detecting whether an absolute value of input voltage is over a specific voltage difference or not. The squelch circuit according to the present invention comprises: a first differential amplifier for receiving first and second input signals, for sensing a first voltage difference between the first and second input signals and for outputting a first sensing signal when the first voltage difference is over a specific positive value; a second differential amplifier for receiving the first and second input signals, for sensing a second voltage difference between the first and second input signals and for outputting a second sensing signal when the second voltage difference is over a specific negative value; an offset current determining unit coupled to the first and second differential amplifiers for respectively controlling first and second offset currents of the first and second differential amplifiers to determine the specific positive and negative values; and an output unit for outputting a squelch signal in response to the first and second sensing signals.

Dependencies are inferred from the claim text.