Patent ID: 6340900
Filing Date: 2002-01-22
Classification: G01R,H03L

Abstract:
A phase detector, comprising:(A) a load circuit formed by transistors and coupled to (1) a power supply and (2) a first node and a second node, wherein the first and second nodes form an output of the phase detector; (B) a capacitive circuit having (1) a first capacitor coupled to the first node and ground and (2) a second capacitor coupled to the second node and the ground; (C) a first circuit having a first end coupled to the first node and a second end coupled to the second node, the first circuit detecting a phase difference between a first signal and a second signal, wherein the first circuit causes a first error current; (D) a second circuit having the same circuit configuration as the first circuit but having a first end coupled to the second node and a second end coupled to the first node, wherein the second circuit causes a second error current that cancels the first error current due to cross-connection of the second circuit with respect to the first circuit, wherein each of the first and second circuits receives the first and second signals, wherein the first and second circuits are controlled by the second signal to function with respect to the first and second signals at the same time such that the second error current cancels the first error current in order for the first circuit to detect the phase difference between the first and second signals with minimized detection error.