A Bandwidth-Adaptive Preamplifier

• Published in: IEEE journal of solid-state circuits Vol. 48; no. 9; pp. 2142 - 2153
• Main Authors: Dingkun Du, Odame, Kofi M.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2013; Institute of Electrical and Electronics Engineers
• Subjects: Adaptive; Amplifiers; analog circuit; Analog circuits; analog front end (AFE); Applied sciences; Bandwidth; Circuit properties; Clocks; Design. Technologies. Operation analysis. Testing; differential difference amplifier (DDA); Dynamic range; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; envelope detector; Exact sciences and technology; Hardware; hysteretic comparator; Input-output equipment; Integrated circuits; low power; microphone; OTA-C filter; Power demand; power efficient; preamplifier; reconfigurable; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; sensor interface; Signal to noise ratio; Speech; subthreshold; wearable sensor; Analog circuit; Envelope detector; Microphone; Prototype; Input signal; Differential amplifier; differential difference amplifier (DDA); analog front end (AFE); Degradation; reconfigurable; Hysteresis loop; Preamplifier; sensor interface; Adaptive; User interface; Complementary MOS technology; Electric power consumption; Reconfigurable architectures; Comparator circuit; Harmonic distortion; Transconductance; Damaging; Operational amplifier; wearable sensor; Measurement sensor; OTA-C filter; hysteretic comparator; power efficient; low power; subthreshold; Low-power electronics; Speech processing
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2013.2266869

We propose an adaptive microphone preamplifier that adjusts its power consumption according to the input signal's bandwidth. A chip prototype of the adaptive preamplifier for speech processing was fabricated in a 0.5-μm CMOS process. The adaptive preamplifier's measured input referred noise is 3 μV rms and its total harmonic distortion is -40 dBc for an 80-mV rms input amplitude. These noise and distortion specifications remain virtually constant over the preamplifier's range of bandwidth adaptation. The adaptive preamplifier consumes 65 μW of power. This is achieved with no degradation in speech quality, when compared to a conventional preamplifier of fixed bandwidth, and as measured by the perceptual evaluation of speech quality (PESQ) score.