Patent ID: 8035437
Filing Date: 2011-10-11
Classification: H03K,H03L

Abstract:
1. A phase interpolator receiving a first signal having an oscillation frequency and providing a second signal having said oscillation frequency and being phase-shifted with respect to the first signal which depends on a third signal, the interpolator comprising: a variable phase-shifter circuit receiving the first signal and providing the second signal, the phase-shifter circuit comprising an astable multivibrator circuit having a first branch and a second branch arranged in parallel between first and second supply terminals, and means capable of providing, in each of the first and second branches, a first current controlled by a fourth signal (Is), the means comprising a first current source capable of providing a second constant current, and wherein the fourth signal is a third variable current which adds to the second current, which results in a variation of a free oscillation frequency (Fo); a phase comparator capable of receiving the first and second signals and of providing a fifth signal representative of said phase shift; and a unit capable of providing the fourth signal, which depends on the third and fifth signals, wherein the phase comparator is capable of providing the fifth signal in the form of a binary signal having a duty cycle which depends on said phase shift, wherein the first and second signals are binary signals alternating between first and second states and wherein the phase comparator is capable of providing the fifth signal in a third state when, the first signal having a phase lead over the second signal, the first signal is in the first state, the second signal being in the second state, and of providing the fifth signal substantially in a fourth state otherwise.