An FPGA-based wideband PLL without significant quantization noise

An effective mean of eliminating the quantization noise effect at the voltage controlled oscillator input of phase-locked loops using digital filters is proposed in this paper. The solution relies on a simple all-digital sigma-delta modulator to lower the requirements on the digital to analog converter, while keeping the quantization noise effect well under the voltage controlled oscillator inherent phase noise. The proposed solution has been verified experimentally, showing a phase noise performance improvement of 11.5 dB without any other modification than an increase in logic complexity of 93 slices on a Xilinx FPGA.