A Low-Cost Low-Power 900MHz Digital Frequency Synthesizer with Built-in Spread Spectrum Modulation

摘要

This paper describes digital frequency synthesizer (DFS) circuit using second order sigma-delta noise shaping with built in SSCG modulation. This circuit has been designed using 90nm 1.0V CMOS technology in TSMC process that occupies an area of 0.08mm~2 with maximum power consumption of 2mW. The circuit can support input frequency ranging from 20MHz to 100MHz and generate output frequency, ranging from 300MHz to 900MHz. The peak-peak periodic jitter obtained is 63ps and 45ps for 300MHz and 900MHz output frequency respectively. This circuit can also generate spread spectrum modulation with maximum rate of 100KHz and maximum depth of 6% using built-in circuit.