TI First to Create Digitally Controlled Microphone Preamplifier IC

12/22/2003 - Texas Instruments Incorporated (TI) (NYSE: TXN) 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.

"There is no other device on the market which offers this level of performance, functionality and integration, making it very compelling for systems where the PGA2500 is used as a mic preamp in front of an audio A/D converter," said Mike Centorino, marketing manager for TI's Burr-Brown Pro Audio products. "Since the PGA2500 is digitally controlled, it is especially useful in systems where the customer is controlling the gain of the mic preamp from a remote location. This innovative device provides an unmatched solution for audio designers who have been developing discrete digitally controlled mic preamps."

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.

Available Today
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.

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