Waveform conversion circuit with reduced jitter

摘要

An AC-inverting amplifier for a waveform conversion circuit includes a first MOS transistor of a first conductivity type having a gate that receives an input signal, a drain that provides an inverted amplified output signal, and a source coupled to a first power supply voltage. A current source provides a first bias current and a second bias current in proportion to the first bias current. The second bias current is coupled to the drain of the first MOS transistor to bias the first MOS transistor. The first bias current has a magnitude that is determined by a DC voltage applied at the gate of the first MOS transistor.

主权项

1. A sinusoidal-to-square waveform conversion circuit, comprising:
a first AC-inverting amplifier comprising:
a first MOS transistor of a first conductivity type, having a gate configured to receive an input signal, a drain configured to provide an inverted amplified output signal, and a source coupled to a first power supply voltage; anda current source configured to provide a first bias current and a second bias current in proportion to the first bias current, wherein the second bias current is provided to the drain of the first MOS transistor to bias the first MOS transistor; and a bias circuit configured to apply a bias voltage to the gate of the first MOS transistor to bias the first AC-inverting amplifier at a predetermined static operation point, wherein the first bias current has a magnitude that is determined by the bias voltage applied on the gate of the first MOS transistor, wherein the current source comprises:
a current mirror that provides the first and second bias currents;a second MOS transistor of the first conductivity type having a drain that receives the first bias current, and a source coupled to the first power supply voltage, wherein the second MOS transistor is biased in a saturation region such that the magnitude of the first bias current passing therethrough is determined by the bias voltage on the gate of the first MOS transistor; anda low-pass filter having an input terminal connected to the gate of the first MOS transistor and an output terminal connected to a gate of the second MOS transistor, for filtering the sine wave input signal, wherein the current mirror comprises:
third and fourth MOS transistors of a second conductivity type opposite to the first conductivity type, the third and fourth MOS transistors having sources both coupled to a second power supply voltage, drains connected respectively to the drains of the first and second MOS transistors, and gates connected to each other and further to the drain of the fourth MOS transistor, andwherein the bias voltage applied by the bias circuit to the gate of the first MOS transistor equals half of an absolute value of a difference between the first power supply voltage and the second power supply voltage.