Patent ID: 7545195
Filing Date: 2009-06-09
Classification: H03K

Abstract:
1. A variable delay element, comprising: a first input stage circuit and a second input stage circuit not operably connected directly to one another, the first and second input stage circuits each comprising respective charge pumping and discharging circuits and being configured to receive the same input signal as inputs thereto, the first input stage circuit further comprising a variable current source controlled by a first variable control voltage provided thereto, the second input stage circuit further comprising a variable current sink controlled by a second variable control voltage provided thereto, the first and second input stage circuits providing first and second outputs therefrom, respectively, and a third output stage circuit comprising at least first and second transistors having inputs operable connected, respectively, to the first and second outputs, the third output stage circuit providing a third output signal that is a delayed version of the input signal; wherein the first variable control voltage is different from the second variable control voltage, variation of the first and second variable control voltages causes a variable delay between the input and third output signals, and the third output signal provided by the third output stage circuit is capable of swinging between a supply voltage and ground regardless of the amount of the delay.