Title :
A 0.2-mW CMOS ΣΔ modulator for speech coding with 80 dB dynamic range
Author :
vanderZwan, E.J. ; Dijkmans, E. Carel
Author_Institution :
Philips Res. Lab., Eindhoven, Netherlands
fDate :
12/1/1996 12:00:00 AM
Abstract :
A CMOS ΣΔ modulator for speech coding with continuous-time loopfilter is presented. Compared to switched-capacitor implementations, the relaxed bandwidth requirements of the active elements of the loopfilter reduce the power consumption. Furthermore, the need for an antialiasing filter at the modulator input is eliminated. A fourth-order, 64× oversampling ΣΔ modulator for application in portable telephones was designed and shows 80 dB dynamic range over the 300-3400 Hz voice bandwidth. Its input is directly connected to the microphone (maximum 40 mVRMS). Total harmonic distortion (THD) is below -70 dB at 95 μA current consumption from a 2.2 V supply voltage. The active die area of the modulator is 0.5 mm2 in a standard 0.5-μm CMOS process
Keywords :
CMOS integrated circuits; audio equipment; continuous time filters; harmonic distortion; modulators; sigma-delta modulation; speech coding; 0.2 mW; 0.5 micron; 2.2 V; 300 to 3400 Hz; 3100 Hz; 95 muA; CMOS ΣΔ modulator; THD; continuous-time loopfilter; dynamic range; fourth-order oversampling ΣΔ modulator; portable telephones; power consumption; sigma-delta modulator; speech coding; total harmonic distortion; Bandwidth; Dynamic range; Energy consumption; Microphones; Modulation coding; Power harmonic filters; Speech coding; Telephony; Total harmonic distortion; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
