High integration for next-generation speech chips

Edited by the Electronicstalk editorial team May 26, 2003

New highly integrated speech components and design tools enable voice record/playback features for consumer, business and entertainment products.

New highly integrated speech components and design tools enable voice record/playback features for consumer, business and entertainment products.

The new devices include: the Oki ML2302 featured for voice organisers and similar products; the Oki ML2500B with direct storage of analogue voice signals for optimum audio quality in mobile handset voice memos; and the Oki MS87V1021 featuring DRAM storage, fixed message ROM and versatile playback controls.

All new devices feature generous on-chip memory, enhanced compression algorithms and low voltage operation for extended battery life in hand held applications.

The Oki ML2302 is a 64-pin TQFP digital record and playback device featuring dual built in 1024bit FIFO memories, enabling up to 32ms buffering time on record and playback channels depending on sampling frequency and compression algorithm.

Five compression algorithms are supported, including 2bit standard ADPCM2, 4/5/6/7bit Oki ADPCM2, 4bit Oki ADPCM, 8/16bit straight ADPCM and 8bit Oki nonlinear PCM.

The device operates at 2.7 to 3.6V and includes built-in voice level detection, noise injection function, 14bit D/A and A/D convertors, volume control circuit, lowpass filters for record and playback, and a 100mW, 8ohm speaker amplifier.

Oki's advanced, proprietary compression algorithms refine standard adaptive differential PCM (ADPCM), to deliver enhanced speech quality through greater internal computation accuracy and extra quantisation steps.

This technology allows designers to optimise the system bitrate, audio quality level and memory requirements.

The ML2500B record-playback device uses analogue multilevel storage technology to eliminate noise and distortion introduced by digital conversion.

It delivers high sound quality and record/playback storage up to 256s, to serve voice memo applications in mobile handsets and other personal data devices.

The ML2500B stores uncompressed analogue source signal directly into on-chip 1Mbit-cell Flash memory, and is fully controllable via an industry standard serial peripheral interface (SPI).

No back up is required, and the low operating voltage of 2.7-3.6V is compatible with leading handheld supplies.

The MS87V1021 is a single-chip digital recording and playback solution, featuring a serial interface for control by a microcontroller.

Two 4bit compression algorithms are supported, and the device has a 2Mbit DRAM for storage of recorded data.

A further 512Kbit mask ROM stores additional, standard messages.

Versatile features include delayed playback, retroactive playback, fast forward and rewind.

The device allows a complete record/playback system to be constructed by simply adding a microphone, speaker driving amplifier and a speaker.

Both the ML2500B and MS87V1021 are available in 32-pin SOP type 1 package, and each is supported by an evaluation board that allows human speech features to be rapidly integrated into many products.