A Compact and Low-Power Fractionally Injection-Locked Quadrature Frequency Synthesizer Using a Self-Synchronized Gating Injection Technique for Software-Defined Radios

Abstract

This paper describes a compact and low-power frequency synthesizer with quadrature phase output for soft- ware-defined radios (SDRs). The proposed synthesizer is con- structed using a core phase-locked loop (PLL), which is coupled with a fractional- N injection-locked frequency divider (ILFD). The fractional- N injection-locking operation is achieved by the proposed self-synchronized gating injection technique. The principle of a fractional- N injection locking operation and the concept of the proposed circuits are described in detail. Analys is for predicting the locking range of the proposed fractional- N ILFD is investigated. A digital calibration scheme is adopted in order to compensate for proc ess, voltage, and temperature (PVT) variations. Implemente di na6 5n mC M O Sp r o c e s s ,t h i s work demonstrates continuous frequency coverage from 10 MHz to 6.6 GHz with quadrature phase output while occupying a s m a l la r e ao f0 . 3 8m m 2 and consuming 16 to 26 mW, depending on the output frequency. The normalized phase noise achieves -135.3 dBc/Hz at an offset of 3 MHz and -95.1 dBc/Hz at a n offset of 10 kHz, both from a carrier frequency of 1.7 GHz.