Title :
A voice-band audio processor IC for CDMA applications
Author :
Bakkaloglu, Bertan ; Evans, Brian L. ; Gata, D. George ; Hellums, James R. ; Higdon, J.J. ; Hochschild, James R. ; Lin, Gary ; Muza, John M. ; Zhang, Zhengwei
Author_Institution :
Dept. of Mixed Signal Design, Texas Instrum. Inc., Dallas, TX, USA
Abstract :
A 2.7 V voice-band audio processor (VBAPTM) IC for CDMA wireless handsets as presented, The chip consists of transmit (uplink) and receive (downlink) audio channels and runs at a nominal current consumption of 9.1 mA. The transmit channel has two differential microphone inputs with external filtering and gain option for signal conditioning before a ΣΔ ADC. The transmit channel pre-emphasis filter, receive channel filter, part of transmit gain, receive gain, receive volume control and sidetone gains are achieved by a single DSP core. The receive channel has a differential and a single-ended speaker interface which can deliver 35 mW and 10 mW to a 32 Ω load respectively. The PCM encoding and decoding can be achieved in both linear and μ-law companded modes. Due to the PLL/clock recovery circuitry the 13-bit ΣΔ voiceband codec is immune to system clock jitter up to 37%
Keywords :
code division multiple access; decoding; delta-sigma modulation; low-power electronics; mixed analogue-digital integrated circuits; mobile radio; pulse code modulation; speech codecs; speech coding; spread spectrum communication; voice communication; ΣΔ ADC; μ-law companded mode; 10 mW; 13 bit; 2.7 V; 35 mW; 9.1 mA; CDMA applications; CDMA wireless handsets; DSP core; PCM decoding; PCM encoding; PLL/clock recovery circuitry; VBAP IC; differential microphone inputs; differential speaker interface; downlink audio channel; external filtering; gain option; linear mode; low power audio codec IC; pre-emphasis filter; receive audio channel; receive channel filter; receive volume control; sidetone gains; signal conditioning; single-ended speaker interface; system clock jitter immunity; transmit audio channel; uplink audio channel; voice-band audio processor IC; voiceband codec; Application specific integrated circuits; Clocks; Digital signal processing; Downlink; Filtering; Filters; Microphones; Multiaccess communication; Phase change materials; Telephone sets;
Conference_Titel :
Circuits and Systems, 1998. Proceedings. 1998 Midwest Symposium on
Conference_Location :
Notre Dame, IN
Print_ISBN :
0-8186-8914-5
DOI :
10.1109/MWSCAS.1998.759536
