Fast Digital Coarse Tuning Loop for Wide-band Dual-loop Frequency Synthesizers

A new coarse tuning loop for wide-band dual-loop frequency synthesizer is presented in this paper. The proposed coarse tuning structure is composed of successive approximation register (SAR) and new structure frequency comparator. The frequency comparison error is analyzed and shows less comparison error compared with reported ones. This structure also reuses the programmable divider as a part of the coarse tuning loop and the circuit is greatly simplified