Analog processing circuits for a 1.1 V 270 μA mixed-signal hearing aid chip

This paper presents a compact Micro-Electro-Mechanical System (MEMS) microphone digital readout system. The system is characterized by a low-dropout regulator (LDO) and a pre-amplifier and programmable-gain amplifier (PPA)-less voltage controlled oscillator (VCO)-based ΔΣ modulation technique, which improve compactness and design scalability. Specifically, to improve signal accuracy and maintain loop stability without a gain-tuning range trade-off, an active low pass filter (ALPF) and a current mode feed-forward path (CMFFP) are incorporated in a VCO-based delta-sigma modulation loop. By means of VCOs and SCG phase variation robustness and current source array feedback (CSAFB), the system achieves a high power supply rejection ratio (PSRR) and gain tuning without the need to design an extra regulator and PPA. The design was fabricated using a 180 nm Bipolar-CMOS-DMOS (BCD) process and measured at a 1.2 V supply voltage. According to the measurement results, the signal-to-noise and distortion ratio (SNDR) achieves 62 dB@1 kHz with 40 dB gain and a 10 kHz bandwidth. Furthermore, PSRR@1 kHz is below −55 dB, and power dissipation is within 57 µW.

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Analog processing circuits for a 1.1 V 270 μA mixed-signal hearing aid chip

Cited by 2 publications

References 2 publications

A 1.1-V 270-/spl mu/A mixed-signal hearing aid chip

A 1.1-V 270-/spl mu/A mixed-signal hearing aid chip

A Compact MEMS Microphone Digital Readout System Using LDO and PPA-Less VCO-Based Delta-Sigma Modulation Technique

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