Title :
A 1.8-V ΔΣ modulator interface for an electret microphone with on-chip reference
Author :
Bajdechi, Ovidiu ; Huijsing, Johan H.
Author_Institution :
Delft Univ. of Technol., Netherlands
fDate :
3/1/2002 12:00:00 AM
Abstract :
The design of a delta-sigma (ΔΣ) analog-to-digital converter (ADC) for direct voltage readout of an electret microphone is presented. The ADC is integrated on the same chip with a bandgap voltage reference and is designed to be packaged together with an electret microphone. Having a power consumption of 1.7 mW from a supply voltage of 1.8 V, the circuit is well suited for use in mobile applications. The single-loop, single-bit, fourth-order ΔΣ ADC operates at 64 times oversampling for a signal bandwidth of 11 kHz. The measured dynamic range is 80 dB and the peak signal-to-(noise+distortion) ratio is 62 dB. The harmonic distortion is minimized by using an integrator with an instrumentation amplifier-like input which directly integrates the 125-mV peak single-ended voltage generated by the microphone. A combined continuous-time/switched-capacitor design is used to minimize power consumption
Keywords :
continuous time systems; delta-sigma modulation; electrets; harmonic distortion; low-power electronics; microphones; readout electronics; reference circuits; switched capacitor networks; 1.7 mW; 1.8 V; 11 kHz; analog-to-digital converter; continuous-time design; delta-sigma modulator interface; direct voltage readout; dynamic range; electret microphone; harmonic distortion; instrumentation amplifier; integrator; mobile applications; on-chip low-voltage bandgap voltage reference; power consumption; signal-to-noise-and-distortion ratio; single-ended input; switched-capacitor design; Analog-digital conversion; Bandwidth; Circuits; Delta modulation; Electrets; Energy consumption; Microphones; Packaging; Photonic band gap; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
