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First Digitally Controlled Microphone Preamplifier?

Tucson, AZ (Dec. 19, 2003) – Texas Instruments Incorporated (TI) introduced the industry's first digitally controlled microphone preamplifier IC (integrated circuit) from the company's Burr-Brown Pro Audio product line. The PGA2500 is designed for use as a front end for high-performance analog-to-digital converters in a variety of professional audio applications, such as microphone preamplifiers, digital audio mixers and recorders, and broadcast and studio equipment.

Prior to the integrated PGA2500, a discrete mic preamp design included a combination of ICs and discrete parts to achieve a digitally controlled solution. Such a solution commonly incorporated instrumentation amplifiers, digital potentiometers/volume controls, switches/relays and discrete op amps. In addition to eliminating numerous components, the PGA2500 offers higher dynamic range, lower THD+N, and lower equivalent input noise versus gain when compared to discrete designs.

The PGA2500 features a wide gain range of 10dB through 65dB (1dB per step), allowing the IC to be used with a variety of microphones. Gain settings and internal functions are programmed using a 16-bit control word, which is loaded using a simple serial port interface. A serial data output pin provides support for a daisy-chain connection of multiple PGA2500 devices. Other features include low noise, wide dynamic range and a differential signal path.

An on-chip DC servo loop is employed to minimize DC offset, while a common-mode servo function may be used to enhance common-mode rejection. Four programmable digital outputs are provided for controlling the external switching of input pads, phantom power, high pass filters and polarity reversal functions. The device operates on a +/-5V supply.

The PGA2500 is packaged in a 28-lead SSOP, and is available now from TI and its authorized distributors. The PGA2500 is priced from $9.95 in 1,000 piece quantities (suggested resale pricing). An evaluation module (EVM) is available.

Texas Instruments Incorporated, Semiconductor Group, SC-03263 Literature Response Center PO Box 954 Santa Clara, CA 91380. Tel: 800-477-8924

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