TI Debuts CODEC, Process

Electronic News, Sept 7, 1998 by Jeff Dorsch

dallas -- Texas Instruments has introduced a mixed-signal voice codec for use in code division multiple access (CDMA)-based wireless handset applications.

The new TWL1101 Voice-Band Audio Processor (VBAP) (CODEC) is an enhancement of TI's existing VBAP products.

At the same time, TI's Wireless Communications business unit is rolling out LinEPIC III, a CMOS process for its analog and mixed-signal semiconductors. Use of LinEPIC III in certain chips is projected to help reduce the number of components going into wireless phones, continuing the shrinkage in the size of these popular handsets. According to TI, the process is capable of enabling designers to eliminate up to 20 components from their systems.

24M CDMA Phones In '99?

Market projections indicate there will be 24 million CDMA handsets sold in 1999, according to Michael Glatz, who is in strategic marketing for TI's Wireless Communications business unit. If TI can capture only a portion of that business with the TWL1101 and other chips, it will do very well in the CDMA component segment.

The TWL1101 VBAP is available in volume today, priced at $3.45 a unit in quantities of 1,000 and packaged in a 48-pin thin quad flat pack (TQFP). TI plans to offer the part in a space-saving MicroStar ball grid array (BGA) package in 4Q98.

"The announcement of the TWL1101, coupled with TI's new LinEPIC III process technology, establishes a solid foundation for TI to provide an analog/mixed-signal roadmap for third-generation wireless communication systems," said Gilles Delfassy, a TI VP and worldwide director of Wireless Communications, in a statement.

TI's VBAP devices are used in wireless cellular and personal communication systems (PCS) phones, among other applications. Like the earlier VBAPs, the TWL1101 performs the transmit encoding (analog-to-digital conversion) and receive decoding (digital-to-analog conversion) and provides transmit-and-receive filtering for wireless phones and other voice-band communication systems.

In addition to supporting CDMA systems, the device is also compatible with any other type of application requiring an interface between a human voice and a digital signal processor (DSP) or a microcontroller, TI said. Such systems include hands-free cellular kits, speakerphones, answering machines, voice modems, digital intercoms, digital public exchanges (PBXs), wireless local loop handsets, voice interfaces to computers and voice-activated security systems.

Varied Enhancements

Among the TWL1101 enhancements are Sigma-Delta technology and digital filtering, which require less power and produce a higher-quality voice signal compared with earlier codecs, TI said. Added sidetone produces a more natural voice sound from the speaker and also simplifies DSP programming by offloading sidetone algorithms. To simplify system clocking, the device generates all necessary internal clocks.

All the new features of the TWL1101 VBAP are fully programmable through the I2C Bus serial interface. This programmability is designed to give designers added flexibility for controlling all channeling, filter response and bidirectional gain settings. Two selectable microphone inputs and two selectable speaker outputs ease the implementation of after-market car kits.

Mr. Glatz said the part operates at a maximum of 2.7 volts. Access to development tools and other information about the TWL1101 is available on the TI Web site at www.ti.com/sc/docs/wireless/home.htm.

Using devices made with TI's new LinEPIC III process, designers of wireless handsets may be able to eliminate 15 to 20 components, TI claims. The process enables the integration of the entire battery management and analog baseband sections, two of the four major system blocks for digital cellular and PCS phones.

Scott Cooper, mixed-signal products marketing manager for Wireless Communications, said that the new process is a dual-gate oxide process capable of producing device dimensions as fine as 0.37-micron (L-effective). (Analog/mixed-signal devices typically have dimensions larger than all-digital devices, which have gone through the quarter-micron level and are now pushing to 0.18-micron and below.)

TI noted that the battery management section of a wireless phone design serves to control and conserve power distribution in the system. The analog baseband section performs analog signal processing, filtering and conversion that enables the phone's DSP to communicate with the microphone, speaker and radio-frequency (RF) section of the phone.

In the typical digital cellular or PCS phone handset today, these two sections require up to 20 ICs and discrete components. The LinEPIC III process is capable of integrating all of these components into a few devices, or even a single device, according to TI.

LinEPIC III is the successor to TI's LinEPIC II process, which Mr. Cooper said was good in integrating the analog baseband section but not as proficient in the power management section. LinEPIC is a mixed-signal version of the TI digital CMOS process known as EPIC, which stands for Enhanced Performance Implanted CMOS.