Abstract: A thermal accelerometer device that provides a compensation for sensitivity variations over temperature. The thermal accelerometer includes signal conditioning circuitry operative to receive analog signals representing a differential temperature is indicative of a sensed acceleration. The signal conditioning circuitry includes serially connected A-to-D and D-to-A converters, which implement a temperature dependent function and process the received signals to provide a compensation for sensitivity variations over a range of ambient temperature. To provide a ratiometric compensation for variations in power supply voltage, a buffered voltage proportional to the supply voltage is provided as a reference voltage to the D-to-A converter. The thermal accelerometer includes a self-test circuit for verifying the integrity of a heater, temperature sensors, and circuitry included within the device.

Abstract: An integrated convective accelerometer device. The device includes a thermal acceleration sensor having a thermopile and a heater element; control circuitry for providing closed-loop control of the thermopile common-mode voltage; an instrumentation amplifier; clock generation circuitry; voltage reference circuitry; a temperature sensor; and, output amplifiers. The device can be operated in an absolute or ratiometric mode. Further, the device is formed in a silicon substrate using standard semiconductor processes and is packaged in a standard integrated circuit package.

Abstract: A modulation limiter that eliminates over-deviation otherwise caused by asymmetrical modulation signals in a frequency modulated (FM) transmitter. The output signal from a conventional modulation clipper is integrated, multiplied by a gain constant, and subtracted from the input, which causes the clipper output to have zero average and a high-pass frequency response with a time constant determined by the feedback gain. The zero average value allows the clipped modulation signal to be coupled to a modulator without over-deviation caused by shifts in the average value of the clipped signal, and the high-pass response can be used to give the modulation signal pre-emphasis.

Abstract: An improved switched capacitor circuit configuration is disclosed which exhibits improved low voltage supply operation and improved charge injection cancellation performance. In the preferred embodiment of a switched capacitor integrator, the improvement is realized by the particular configuration of a switched tub switch on the input, single N-channel devices at the summing junction, skewing the analog ground V.sub.AG downward, and delaying the clock signals to turn off the switches at the summing junction before the charge injection of the switched tub switch is realized.

Abstract: A differential amplifier is provided which has a low systematic offset voltage and a small variation in quiescent current with respect to variations in processing and temperature while providing low input referred noise and good output drive capability. Each transistor of a differential input pair of transistors is coupled to a plurality of series-connected transistors which are fabricated with substantially equal control electrode dimensions to form composite load tranistors. An output stage having conventional source and sink transistors is coupled to the differential pair of transistors. The sink transistor is implemented as a composite transistor by a plurality of parallel-connected transistors, each also having substantially the same control electrode dimension. Since all the ratioed transistors have equal control electrode dimensions, variations over processing and temperature are minimized.