A Δ ∑ fractional-N frequency synthesizer for FM tuner using low noise filter and quantization noise suppression technique

A Δ∑ fractional-N frequency synthesizer fabricated in a 130 nm CMOS technology is presented for the application of an FM tuner. A low noise filter, occupying a small die area and decreasing the output noise,is integrated on a chip. A quantization noise suppression technique, using a reduced step size of the frequency divider, is also adopted. The proposed synthesizer needs no off-chip components and occupies an area of 0.7 mm2.The in-band phase noise(from 10 to 100 kHz) below –108 dBc/Hz and out-of-band phase noise of –122.9 dBc/Hz(at 1 MHz offset) are measured with a loop bandwidth of 200 kHz. The quantization noise suppression technique reduces the in-band and out-of band phase noise by 15 dB and 7 dB respectively. The integrated RMS phase error is no more than 0.48. The proposed synthesizer consumes a total power of 7.4 mW and the frequency resolution is less than 1 Hz.