ADC with sample and hold
Representative implementations of devices and techniques provide analog to digital conversion of multiple parallel analog inputs. An input interface is arranged to organize the parallel analog inputs and an analog-to-digital converter (ADC) is arranged to sequentially convert the multiple parallel analog inputs to digital results.
1. A device, comprising:
a plurality of sample and hold (SH) circuits, at least one of the plurality of SH circuits arranged to receive a plurality of analog signals;
a multiplexer circuit arranged to receive a plurality of outputs of the plurality of SH circuits and sequentially make the outputs available for conversion, the multiplexer to provide a serially formed signal that comprises at least one signal output from each of the plurality of SH circuits, the multiplexer to receive an initialization voltage;
an analog-to-digital converter (ADC) arranged to serially convert the outputs to respective digital results, the ADC to receive the initialization voltage to cancel the initialization voltage received by the multiplexer; and
a demultiplexer to receive the digital results and to provide digital output signals to multiple channels coupled to the demultiplexer.
2. The device of claim 1 , wherein the plurality of SH circuits comprise passive SH circuits.
3. The device of claim 1 , wherein the digital results comprise at least one of binary signals or voltage values.
4. The device of claim 1 , wherein the digital results are comprised as a serial output signal from the ADC.
5. The device of claim 1 , wherein each one of the digital results is provided to a unique one of the multiple channels.
6. A system, comprising:
a plurality of sample and hold (SH) circuits, each of the plurality of SH circuits arranged to receive a plurality of analog signals and to output a sample value based on at least one of the plurality of analog signals;
a multiplexer circuit arranged to receive a quantity of sample values including the sample value of each of the plurality of SH circuits and to sequentially output each sample value of the quantity of sample values as part of a serial signal that comprises a plurality of sample values, at least one of the plurality of sample values associated with the serial signal corresponding to each of the plurality of SH circuits, the multiplexer to receive an initialization voltage;
an analog-to-digital converter (ADC) arranged to serially convert each sample value to a respective digital result, the ADC to receive the initialization voltage to cancel the initialization voltage received by the multiplexer; and
a demultiplexer arranged to direct each digital result to at least one of multiple outputs.
7. The system of claim 6 , further comprising a plurality of channels, each channel including at least one SH circuit and at least one associated output.
8. The system of claim 6 , further comprising a voltage divider arranged to divide each of the plurality of analog signals by a preselected value to scale the plurality of analog signals.
9. The system of claim 6 , further comprising a multiplexer switch associated with each of the plurality of SH circuits and arranged to couple each of the plurality of SH circuits to the ADC.
10. The system of claim 6 , further comprising at least one sample switch coupled to each SH circuit of the plurality of SH circuits and arranged to determine a sample duration for the plurality of SH circuits.
11. The system of claim 6 , wherein the ADC comprises a successive approximation ADC (SA-ADC).
12. The system of claim 11 , wherein the SA-ADC comprises a switched capacitor type SA-ADC.
13. The system of claim 11 , wherein the SA-ADC comprises a digital-to-analog conversion (DAC) circuit, a comparator, and a successive approximation register.