Patent ID: 8081023

Claim:
A phase shift circuit comprising: a first delay circuit comprising a first delay element and a second delay element coupled to the first delay element, wherein the first delay circuit is operable to receive an input signal and provide a first delayed signal; an inverter coupled to the first delay circuit to invert the first delayed signal and provide an output signal that is phase shifted by 360 degrees relative to the input signal; and a second delay circuit comprising the first delay element, wherein the second delay circuit is operable to provide an output signal that is phase shifted by 90 degrees relative to the input signal, wherein: the first delay element comprises a first delay chain, wherein the first delay chain is operable to receive the input signal and produce a first plurality of output signals, where the first plurality of output signals are delayed versions of the input signal; the first delay circuit further comprises a first selector coupled to the first delay chain, wherein the first selector is operable to select one output signal of the first plurality of output signals; and the second delay circuit further comprises: a third selector coupled to the first delay chain, wherein the third selector is operable to select an output signal of the first plurality of output signals; a half unit delay element coupled to the third selector; and a fourth selector coupled to the third selector and the half unit delay element.