Patent ID: 9042854
Filing Date: 2015-05-26
Classification: H03B,H03L

Abstract:
1. An auto-tuning circuit for tuning a voltage controlled oscillator (VCO) during a coarse tuning mode, the auto-tuning circuit comprising: a prescaler circuit configured to receive a VCO clock signal from the VCO and to generate a divided clock signal, the prescaler circuit having a selectable division ratio; a counter module including a first counter and a second counter, the first counter configured to operate with the second counter to control a value of the selectable division ratio of the prescaler circuit, the counter module configured to receive a division control signal M and the divided clock signal, and to generate a phase-frequency detector (PFD) feedback signal based on the division control signal M and the divided clock signal; and a digital processing logic circuit configured to receive the divided clock signal, the digital processing logic circuit including a cycle counter configured to count a number of cycles of the divided clock signal generated by the prescaler circuit that occur during a calibration interval, the digital processing logic circuit further configured to set a value of a capacitor array control signal based on the number of cycles counted.