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Apparajan Ganesan

Douglas G Marsh

A means of integrating a microphone on the same integrated circuit die as other electronics in the system is disclosed. The structure uses solder bump technology to form a gap between an electrode on the silicon and another electrode. Charge is stored on the capacitor so when pressure from sound waves causes one electrode to flex, the capacitance and therefore the charge changes, causing signal current. The structure allows for area efficiency by allowing placement of active silicon circuitry under the microphone.

Means of integrating a microphone in a standard integrated circuit process

The junction difference used for a band gap voltage reference is designed so that it has the needed temperature coefficient without amplification. This is accomplished by the appropriate choice of the number of junctions and the appropriate current densities. Only one polarity of bipolar transistors is required. The noise terms of each junction add in root mean square, rather than be linear amplification, resulting in a lower noise reference than other designs requiring only a single type of bipolar transistors. By using metal available in standard integrated circuit processes to form a resistor, a low temperature coefficient current source can easily be obtained.

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Colorado City, TX, United States of America

Apparajan Ganesan