Analog signal conditioning and digitizing integrated circuit
First Claim
1. An analog signal conditioning and digitizing circuit means comprising an integrated circuit having a channel including a multiplying digital to analog converter, for providing gain adjustment and offset correction to an input voltage and an analog to digital converter operatively connected to the multiplying digital to analog converter for sampling, holding and digitizing the input voltage, said multiplying digital to analog converter comprising a summing and inverting negative feedback amplifier means for gain adjustment and offset noise correction and a correlated double sample circuit means connected to the amplifier means for subtracting or nulling sampled noise of the amplifier.
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Abstract
An analog signal conditioning and digitizing integrated circuit is provided having a multiplying digital to analog converter means (MDAC) including a gain capacitor array and an offset capacitor array, an operational amplifier, a feedback circuit including a feedback capacitor and a feedback clamping transistor, the operational amplifier and feedback circuit connected to the gain and offset capacitor arrays for setting the gain and the amount of offset correction of the MDAC, a correlated double sample circuit including a series capacitor connected to the operational amplifier and a series clamping transistor connected to the junction of the series capacitor and a buffer amplifier for sampling the noise to be substracted and/or nulled across the series capacitor, and an analog to digital converter operatively connected to the MDAC for digitizing the output of the MDAC. In other embodiments the integrated circuit has separate bond pads for the analog signal inputs and outputs of the MDACs and DACs or for implementing feedback/feedforward discrete time transfer functions.
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Citations
14 Claims
- 1. An analog signal conditioning and digitizing circuit means comprising an integrated circuit having a channel including a multiplying digital to analog converter, for providing gain adjustment and offset correction to an input voltage and an analog to digital converter operatively connected to the multiplying digital to analog converter for sampling, holding and digitizing the input voltage, said multiplying digital to analog converter comprising a summing and inverting negative feedback amplifier means for gain adjustment and offset noise correction and a correlated double sample circuit means connected to the amplifier means for subtracting or nulling sampled noise of the amplifier.
- 8. An analog signal conditioning and digitizing circuit means comprising an integrated circuit having a channel including a multiplying digital to analog converter, for providing gain adjustment and offset correction to an input voltage and an analog to digital converter operatively connected to the multiplying digital to analog converter for sampling, holding and digitizing the input voltage, said analog to digital converter means including a sample and hold and conversion means, a comparator means, an offset correction circuit, a successive approximation register, and a serial shift register, the sample and hold and conversion means for sampling and holding an input voltage during conversion, the comparator means operatively connected to the sample and hold and conversion means and offset correction circuit for comparing the output of the sample and hold and conversion means to the output of the offset correction circuit means, the successive approximation register operatively connected to the serial shift register for receiving and sequencing a bit through the sample and hold and conversion means and to the output of the comparator for performing a testing and/or reset operation and outputting a final state.
Specification