SIGNAL PROCESSING DEVICE, DIGITAL OUTPUT MICROPHONE UNIT

PROBLEM TO BE SOLVED: To stabilize fluctuation of digital output to ambient temperature change within a wide temperature range. SOLUTION: In a signal processing device (13) which converts analog electric signals converted from sound by a microphone (1) to digital signals, and outputs them, the device is provided with a preamplifier (15) for amplifying the analog electric signals output from the microphone (1), an analog-digital convertor (12) for comparing the analog electric signals output from the preamplifier (15) with a reference voltage (Vref) for converting the signals from analog to digital, and a reference voltage generation circuit (14) for generating the reference voltage (Vref) and supplying the voltage to the analog-digital convertor (12). The reference voltage generation circuit (14) is provided with an element having a higher temperature dependency in terms of an electric property, compared to other electric circuit elements among electric circuit elements constituting the signal processing device (13), and generates a reference voltage (Vref) corresponding to the voltage between both terminals of the element. COPYRIGHT: (C)2011,JPO&INPIT