A quantization noise cancelling fractional-N type ΔΣ frequency synthesizer using SAR-based DAC gain calibration

A high-speed and low-power adaptable period SAR-based DAC gain calibration is presented for DSM quantization noise suppression, which completes within 10μs while dissipating 0.2mW. The proposed calibration scheme is applied to the fractional-N type frequency synthesizer which adopts an 8-bit noise-cancelling DAC. The frequency synthesizer has a range of 48 to 900 MHz, consumes 11mA from 1.2-V supply and occupies 1.5 × 1.4 mm² in 0.13μm CMOS process. The measurement shows more than 30-dB quantization noise suppression at a 877MHz oscillation frequency which results in the phase noise of -100.7dBc/Hz and -134.5dBc/Hz at 100-kHz and 1.25-MHz offset frequencies respectively.