High-speed, low-power, low-skew, low-voltage differential receiver

摘要

A differential receiver uses an operational trans-conductance amplifier (OTA) to bias the common mode output voltage of the input stage to an inverter threshold voltage, Vth. Large-gate N-MOS transistors are used to provide the bias, and thin-gate NMOS transistors are used as the input switching transistors. A double cross-coupled latch creates a high-gain configuration for small differential signals and limits the gain and swing non-linearly for large signals, without imposing a large transition delay. Matched resistors between the outputs of the double cross-coupled latch provides a measure of the common-mode output voltage of the input stage, and an inverter with input shorted to output provides a measure of an inverter threshold voltage Vth. The OTA compares the measure of the common-mode output voltage and measure of the inverter threshold voltage, and provides a control current to the large-gate NMOS transistors to maintain the mid-point of the common-mode output voltage at a constant voltage.