A Low-Power and Compact Sigma-Delta Voice-band Codec in a 0.18-μm CMOS Technology

A 2.7V fully-integrated voice-band codec for digital cellular phone applications is presented. The codec includes a 16b ΣΔ ADC and DAC, channel filters, PGAs, a low-noise microphone preamplifier and 32 Ω loudspeaker/earpiece drivers. With a PLL for clock generation and a voltage reference integrated on the same chip, the ADC achieves an SNDR of 83 dB and a dynamic range of 88 dB in a 4 KHz signal bandwidth, while the DAC yields 80 dB and 84 dB, respectively. Analog and digital portions of the codec consume only 4.8 mA and 0.53 mA, respectively, and occupy a combined area of 1.0 mm
²
in a 0.18-μm CMOS technology.