US Patent 10523220 Quadrature delay locked loops

Disclosed herein are embodiments of an apparatus and a method for generating a quadrature clock signal. In one aspect, the apparatus includes a first delay circuitry to delay a clock signal according to a first control signal to generate a first delayed clock signal. In one aspect, the apparatus includes a second delay circuitry to delay the clock signal according to a second control signal to generate a second delayed clock signal. In one aspect, the apparatus includes a delay controller forming a first feedback loop with the first delay circuitry, and forming a second feedback loop with the second delay circuitry, where the delay controller determines a difference between the first delayed clock signal and the second delayed clock signal and modifies the first control signal and the second control signal according to the determined difference.