Microphone amplifier for your PDAs

Article By : R. Cittadini, F. Poulin

TS97x family is available in thin and compact packages for use in PDA or cellular phones as well as in thin notebook computers.

Many low noise amplifiers exist in the market. Old ones are mainly duals like LM833 and MC33078. But few are able to reach low voltages and are not available in today’s smallest packages. Digital appliances have adopted and kept the typologies used in analog ones. This block is helping to interface the microphone to the A/D converter by buffering, filtering and amplifying the microphone signal.

The TS97x is a family that includes single, dual and quad low-noise operational amplifiers. It features excellent audio characteristics: low distortion (0.003% THD @ F=1kHz) and a 4nV/sqrt(Hz) equivalent input noise voltage with a 1/f corner @ 100Hz. Thanks to those characteristics, it helps keep an optimal signal to noise ratio, a critical point at the entry of the audio amplification chain.

These devices also allow a higher fidelity due to a 4V/μs Slew Rate and 12MHz Gain Bandwidth Product. This enables the amplifier to cope with quick variations of the input signal well over the audio bandwidth.

The family is available in compact packages like SOT23-5 for TS971 or even the thin and rather compact package like TSSOP for TS972/4. This allows them to be used in portable and miniature digital appliances like PDA or cellular phones as well as in thin notebook computers.

Learn more: Download the full application note

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