Patent ID: 7684518

Claim:
A circuit, comprising: a reference signal input having a reference value; a first reversed peak detector configured to generate a first output signal responsive to a first differential input signal and the reference signal, wherein the first reversed peak detector comprises: a first capacitor coupled to a first resistor at a first node, wherein the first capacitor receives the first differential input signal; a first diode coupled to the first node, wherein the first diode drives the first capacitor so that a voltage at the first node is maintained at the reference value when the first differential input signal is equal to a minimum value; a first switch coupled between the first node and ground; a first amplifier, coupled between a second node and the first diode, wherein the first amplifier is configured to receive the reference signal and the first output signal; and a first buffer, coupled between the first node and the second node, wherein the first buffer is configured to generate the first output signal, wherein the first output signal is a replica of the first differential input signal shifted to a value greater than the reference value; and a second reversed peak detector configured to generate a second output signal responsive to a second differential input signal and the reference signal, wherein the second output signal is a replica of the second differential input signal shifted to a value greater than the reference value, and wherein a minimum value of the first output signal is placed above the reference value and a minimum value of the second output signal are greater than or equal to the reference value.