A method of enhancing SAR ADC conversion rate by employing a new value shifted capacitor DAC. The value shifted capacitor DAC decreases largest capacitor to improve the reference voltage settling. The reduction of capacitor is added back onto the smaller capacitor DAC to maintain the same total capacitor value. The binary search outputs are re-combined and processed to produce final binary ADC outputs. The overhead of using value shifted capacitor DAC is the extra latency needed for re-combined logic.

A measurement circuit comprises an electronic circuit, multiple measurement channels, and a combining circuit. The electronic circuit includes a first terminal, a second terminal, and a non-resistive circuit element. Each of the multiple measurement channels includes a differential input connected to the electronic circuit. The differential inputs of the multiple measurement channels are connected in series and include a differential input coupled to the non-resistive circuit element. One input of a differential input of a first measurement channel of the multiple measurement channels is connected to the first terminal of the electronic circuit and one input of a differential input of a second measurement channel of the multiple measurement channels is connected to the second terminal of the electronic circuit. The combining circuit receives multiple outputs from the multiple measurement channels and produce a composite output signal.

An analog-to-digital converter (ADC) is described. This ADC includes a conversion circuit with multiple bit-conversion circuits. During operation, the ADC may receive an input signal. Then, the conversion circuit may asynchronously perform successive-approximation-register (SAR) analog-to-digital conversion of the input signal using the bit-conversion circuits, where the bit-conversion circuits to provide a quantized representation of the input signal. For example, the bit-conversion circuits may asynchronously and sequentially perform the SAR analog-to-digital conversion to determine different bits in the quantized representation of the input signal. Moreover, the ADC may selectively perform self-calibration of a global delay of the bit-conversions circuits. Note that the timing self-calibration may be iterative and subject to a constraint that a maximum conversion time is less than a target conversion time.

A successive approximation register analog-to-digital converter includes a capacitance digital-to-analog converter (CDAC) having, a voltage storing circuit connected to an output terminal of the CDAC and including a plurality of capacitors connected in parallel, an output voltage of the CDAC being stored in a selected one of the capacitors, a selector configured to output a voltage stored in the selected one of the capacitors, a comparator configured to compare a voltage input to an input terminal thereof, which is connected to an output terminal of the CDAC, with a reference voltage, and a successive approximation register configured to control the CDAC based on an output of the comparator, and cyclically control the voltage storing circuit and the selector, such that the output of the selector is output to the output terminal one or more cycles after the output voltage was stored in the selected one of the capacitors.

A pipelined SAR ADC includes a first stage and passive residue transfer is used to boost a conversion speed. Owing to the passive residue transfer, the first stage may be released during a residue amplification phase, cutting down a large part of the first-stage timing budget. An asynchronous timing scheme may also be adopted in both the first- and second-stage SAR ADCs to maximize the overall conversion speed. Lastly, a dynamic amplifier with proposed PVT stabilization technique may be employed to further save power consumption and improve the conversion speed simultaneously.

A semiconductor device according to the present invention has a capacitance DAC (Digital-to-Analog Converter) circuit and a comparator.

The capacitance DAC circuit includes: first capacitors to which input signals are given and each of which has a capacitance value corresponding to a weight of a bit to be converted; and second capacitors to which common voltages are given and whose sum of capacitance values is equivalent to that of the first capacitors. Further, the second capacitors include: a redundant bit capacitor having a capacitance value corresponding to a weight of a redundant bit; and adjustment capacitors each having a capacitance value obtained by subtracting the capacitance value of the redundant bit capacitor from the sum of the capacitance values of the second capacitors.

An analog-to-digital converting circuit for converting an analog signal into a digital signal includes a plurality of reference voltage generators each generating a reference voltage, a plurality of reference voltage decoupling capacitors respectively corresponding to the reference voltage generators, and an analog-to-digital converter generating a comparison voltage based on the reference voltage and generating the digital signal corresponding to the analog signal based on a result of comparing the comparison voltage with the analog signal. At least one different combination of the reference voltage generators and the reference voltage decoupling capacitors is connected to the analog-to-digital converter in each of a plurality of conversion periods.

A first successive approximation register analog-to-digital converter according an embodiment of the present disclosure includes an N-bit (N represents an integer greater than or equal to 5) capacitive digital-to-analog converter including a plurality of capacitive elements. A plurality of first capacitive elements of the plurality of capacitive elements is capacitive elements that have total capacity corresponding to total capacity of a plurality of the capacitive elements corresponding to a whole or a portion of first to (N−1)-th bits, and do not correspond to the first to (N−1)-th bits.

A comparator includes a second stage coupled between a first stage and a third stage. The second stage includes a first transistor coupled to be switched in response to a first output signal coupled to be received from the first stage. The first transistor is coupled generate a second output signal coupled to be received by the third stage. A second transistor is coupled to the first transistor. The first and second transistors are coupled between a first supply voltage and a reference voltage. A second stage current of the second stage is conducted through the first transistor and the second transistor. The second transistor is coupled to be switched in response to a third output signal coupled to be received from the third stage in response to the second output signal.

A subrange analog-to-digital converter (ADC) converts analog image signal received from a bitline to a digital signal through an ADC comparator. The comparator is shared by a successive approximation register (SAR) ADC coupled to provide M upper output bits (UOB) of the subrange ADC and a ramp ADC coupled to provide N lower output bits (LOB). The digital-to-analog converter (DAC) of the SAR ADC comprises M buffered bit capacitors connected to the comparator. Each buffered bit capacitor comprises a bit capacitor, a bit buffer, and a bit switch controlled by one of the UOB of the SAR ADC. A ramp buffer is coupled between a ramp generator and a ramp capacitor. The ramp capacitor is further coupled to the same comparator. The implementation of ramp buffer and the bit buffers as well as their sharing of the same kind of buffer reduces differential nonlinear (DNL) error of the subrange ADC.