US Patent 11258436 Self-calibrating quadrature clock generator and method thereof

A quadrature clock generator includes a variable delay clock generator configured to receive a first clock and a third clock and output a second clock and a fourth clock in accordance with a control signal, wherein the first clock and the third clock are substantially the same but offset in timing by one half of the period; a quadrature phase error detector configured to receive the first clock, the second clock, the third clock, and the fourth clock and output a first phase detection signal and a second phase detection signal, wherein the first phase detection signal represents a relative timing between the first clock and the second clock and the second phase detection signal represents a relative timing between the second clock and the third clock; and an amplifier configured to amplify a difference between the first phase detection signal and the second phase detection signal into the control signal.