A fast automatic frequency calibration technique for a 2-6 GHz frequency synthesizer

Abstract

A fast automatic frequency calibration (AFC) technique is described. For fast AFC operation while eliminating the uncertainty of the initial phase relationship between the reference clock and voltage-controlled oscillator output, two-phase reference clocks are employed. The proposed AFC scheme is applied to a 2-6 GHz frequency synthesizer. The frequency synthesizer is implemented in a 0.18 mu m complementary metal-oxide-semiconductor process and occupies 0.92 mm(2) while the AFC occupies only 0.01 mm(2). The AFC operation is completed in less than 1.6 mu s.