A chopper-stabilized source follower coupling based low-pass filter with noise reduction

作者：Xu Yang^*; Moon Un Ku

来源：Analog Integrated Circuits and Signal Processing, 2018, 95(2): 365-369.

DOI：10.1007/s10470-018-1185-6

• Low-pass filter
• Chopper stabilization
• 1/f noise
• Noise reduction
• Source follower coupling

A highly compact source follower coupling based low-pass filter (LPF) topology is proposed that synthesizes a 3rd-order low-pass transfer function in a single stage with no use of operational amplifiers. Chopper stabilization technique is utilized to reduce 1/f noise for minimizing the in-band integrated noise. Implemented and simulated in a 0.18 mu m CMOS process, the 3rd-order LPF achieves a - 3 dB bandwidth of 20 MHz with a 280 mu A total current from a 1.4 V supply voltage, defining a power-per-pole/bandwidth efficiency of 6.5 mu W/MHz. The output noise density at low frequencies is largely reduced with chopper stabilization technique. The integrated output noise from 10 kHz to 2 MHz is minimized from 22.47 to 7.04 mu V-rms, with a 10.1 dB improvement. The averaged output noise density over the filter bandwidth is 9.4 nV/aeHz, which is mostly contributed by thermal noise of transistors.

• 出版日期2018-5