Patent ID: 7180933

Claim:
A squelch circuit for operating at high frequency, comprising: a squelch input unit having first and second input circuits for receiving positive and negative signals of an input signal and generating two pairs of pre-processed signals, each of the input circuits including a resistor having a first end connected to a current source and a second end connected to a transistor which receives said positive or negative signal; a pre-amplifier for amplifying said two pairs of pre-processed signals and generating two pairs of squelch output signals; and a sampling and decision circuit for receiving said two pairs of squelch output signals and determining a state of said input signal; wherein a pre-processed signal generated at the first end of the resistor of said first input circuit and a pre-processed signal generated at the second end of the resistor of said second input circuit constitute one pair of said two pairs of pre-processed signals, and a pre-processed signal generated at the second end of the resistor of said first input circuit and a pre-processed signal generated at the first end of the resistor of said second input circuit constitute the other pair of said two pairs of pre-processed signals.