A 5-nV/√Hz chopper negative-r stabilization preamplifier for audio applications

This paper presents a low-noise and low-power audio preamplifier. The proposed lownoise preamplifier employs a delay-time chopper stabilization (CHS) technique and a negative-R circuit, both in the auxiliary amplifier to cancel the non-idealities of the main amplifier. The proposed technique makes it possible to mitigate the preamplifier 1/f noise and thermal noise and improve its linearity. The low-noise preamplifier is implemented in 65 nm complementary metaloxide semiconductor (CMOS) technology. The supply voltage is 1.2 V, while the power consumption is 159 μW, and the core area is 192 μm2. The proposed circuit of the preamplifier was fabricated and measured. From the measurement results over a signal bandwidth of 20 kHz, it achieves a signal-to-noise ratio (SNR) of 80 dB, an equivalent-input referred noise of 5 nV/√Hz and a noise efficiency factor (NEF) of 1.9 within the frequency range from 1 Hz to 20 kHz.