Method and apparatus for generating non-skewed complementary signals through interpolation

Abstract

A complementary digital signal generator circuit and method receives a periodic digital signal, such as a square wave, as an input and generates at the output complementary versions of the digital signal delayed by matching increments of delay with minimum skew at GHz frequencies. The digital signal is processed by inverters and interpolators which may be readily matched in size and functional characteristics by close proximity placement on integrated circuits. An inverted and first delayed version of the original digital signal is applied to both inputs of a first interpolator, to generate at the output of the interpolator the complement of the digital signal as delayed by the first delayed and the delay introduced by the interpolator. The inverted and first delayed digital signal is inverted and second delayed by a second matching inverter and applied as one input to a second interpolator. The second input of the second interpolator is the original digital signal. The output of the second interpolator is the digital signal delayed by a corresponding combination of the first delay and the delay introduced by the second interpolator. When the first and second interpolators are matched, in the manner of the first and second inverters, the two interpolator outputs provide the digital signal and its complement with substantially no skew and matching increments of delay.