Recently low-voltage and low-noise analog circuits with sub 100-nm CMOS devices are strongly demanded for implementing mobile digital multimedia and wireless systems. Reduction of supply voltage makes it difficult to attain a signal voltage swing, and device deviation causes large DC offset voltage and 1/f noise. This paper describes noise reduction technique for CMOS analog and RF circuits operated at a low supply voltage below 1 V. First, autozeroing and chopper stabilization techniques without floating analog switches are introduced. The amplifier test chip with a 0.18-µm CMOS was measured at a 0.6-V supply, and achieved 89-nV/ input referred noise (at 100 Hz). Secondly, in RF frequency range, to improve a phase noise of voltage controlled oscillator (VCO), two 1/f-noise reduction techniques are described. The ring VCO test chip achieves 1-GHz oscillation, -68 dBc/Hz at 100-kHz offset, 710-µW power dissipation at 1-V power supply.

A low-noise CMOS amplifier operating at a low supply voltage is developed using the two noise reduction techniques of autozeroing and chopper stabilization. The proposed amplifier utilizes a feedback with virtual grounded input-switches and a multiple-output switched op-amp. The low-noise amplifier fabricated in a 0.18-µm CMOS technology achieved 50-nV/Hz input noise at 1-MHz chopping and 0.5-mW power consumption at 1-V supply voltage.