A N-bit continuous-time sigma-delta modulator, SDM, (800) includes an input configured to receive an input analog signal (302); a first summing junction (304) configured to subtract a feedback analog signal (303) from the input analog signal (302); a loop filter (306) configured to filter an output signal from the first summing junction (304): an N-bit analog-to-digital converter, ADC, comprising at least one 1-bit ADC configured to convert the filtered analog output signal (309) to a digital output signal (314) where each 1-bit ADC comprises at least one pair of comparator latches (336, 356); and a feedback path (316) for routing the digital output signal to the first summing junction (304). The feedback path (316) includes a plurality of digital-to-analog converters, DACs, configured to convert the digital output signal (314) to an analog form. The ADC comprises or is operably coupled to, a calibration circuit (650, 840) coupled to an input and an output of the at least one pair of comparator latches (336, 356) and configured to apply respective calibration signals to individual comparator latches of the at least one pair of comparator latches (336, 356) in a time-Interleaved manner, and calibrate a comparator error of the comparator latches in response to a latched output of the respective calibration signals.

A sensor arrangement includes a sensor having a first terminal and a second terminal, and an amplifier having an amplifier input for applying an input signal and an amplifier output for providing an amplified input signal, the amplifier input being coupled to the second terminal. A quantizer having a quantizer input and a quantizer output is configured to provide a multi-level output signal on the basis of the amplified input signal and a feedback circuit having a feedback circuit input coupled to the quantizer output and a feedback circuit output coupled to the first terminal. The feedback circuit includes a digital-to-analog converter configured to generate an analog signal on the basis of the multi-level output signal, the analog signal being the basis of a feedback signal provided at the feedback circuit output, a feedback capacitor coupled between the feedback circuit output and an output of the digital-to-analog converter, and a voltage source coupled to the feedback circuit output.

A digital-to-analog converter includes a first current source module configured to supply a current I.sub.1 to the digital-to-analog converter, a first switch control module configured to control connection or disconnection between each branch and a trans-impedance amplifier in the digital-to-analog converter based on a to-be-converted digital signal, where the current I.sub.1 supplied by the first current source module flows to the trans-impedance amplifier through a connected branch, and the trans-impedance amplifier is configured to convert the current I.sub.1 supplied by the first current source module into an analog voltage and output the analog voltage.

A DAC driver includes a number of DAC drivers coupled to a load network. A first DAC driver includes a first set of data switches that can be controlled by a first digital input signal. The first DAC driver further includes a first set of output switches, a first set of dump switches and a first set of current sources. Another DAC driver includes a second set of output switches, dump switches, and current sources. The first set of output switches or the second set of output switches are operable to respectively couple either one of the first set of data switches or the first set of current sources to the load network. The first set of dump switches or the second set of dump switches are operable to respectively dump the first set of current sources or the second set current sources into a respective dump load.

A DAC driver includes a number of DAC drivers coupled to a load network. A first DAC driver includes a first set of data switches that can be controlled by a first digital input signal. The first DAC driver further includes a first set of output switches, a first set of dump switches and a first set of current sources. Another DAC driver includes a second set of output switches, dump switches, and current sources. The first set of output switches or the second set of output switches are operable to respectively couple either one of the first set of data switches or the first set of current sources to the load network. The first set of dump switches or the second set of dump switches are operable to respectively dump the first set of current sources or the second set current sources into a respective dump load.

Methods, systems, and apparatus for quantum analog-digital conversion. In one aspect, a method includes obtaining a quantum analog signal; applying a hybrid analog-digital encoding operation to the quantum analog signal and a qudit in an initial state to obtain an evolved state of the qudit, wherein the hybrid analog-digital encoding operation is based on a swap operation comprising multiple adder operations; and providing the qudit in the evolved state as a quantum digital encoding of the quantum analog signal.

Methods, systems, and apparatus for quantum analog-digital conversion. In one aspect, a method includes obtaining a quantum analog signal; applying a hybrid analog-digital encoding operation to the quantum analog signal and a qudit in an initial state to obtain an evolved state of the qudit, wherein the hybrid analog-digital encoding operation is based on a swap operation comprising multiple adder operations; and providing the qudit in the evolved state as a quantum digital encoding of the quantum analog signal.

A magnetic field measuring apparatus includes a digital FLL circuit including ADC that converts a periodically changing voltage output from a SQUID according to a change in a magnetic field into a digital value, a digital integrator that integrates the digital value output from the ADC, a DAC that converts an integrated value output from the digital integrator into a voltage, a converter that converts the voltage output from the DAC into a current, and a coil that generates the magnetic field received by the SQUID, based on the current output from the converter. A calculating device calculates a digital value indicating a flux quantum based on the digital value output from the ADC when the ADC converts the periodically changing voltage output from the SQUID upon receiving the magnetic field generated by a current that is obtained by converting a voltage generated by a voltage generator.

A multiplying digital-to-analog converter (MDAC) includes an operational amplifier, a sampling capacitor circuit, a pre-sampling capacitor circuit, and a switch circuit. During a sampling cycle, the switch circuit connects a pre-defined voltage and reference voltages to the pre-sampling capacitor circuit, disconnects the pre-sampling capacitor circuit from an input port of the operational amplifier and the sampling capacitor circuit, disconnects an output port of the operational amplifier from the sampling capacitor circuit, and connects a voltage input to the sampling capacitor circuit. During a conversion cycle, the switch circuit connects the pre-sampling capacitor circuit to the sampling capacitor circuit, disconnects the pre-defined voltage and the reference voltages from the pre-sampling capacitor circuit, connects the pre-sampling capacitor circuit to the input port of the operational amplifier, connects the output port of the operational amplifier to the sampling capacitor circuit, and disconnects the voltage input from the sampling capacitor circuit.

A multiplying digital-to-analog converter (MDAC) includes an operational amplifier, a sampling capacitor circuit, a pre-sampling capacitor circuit, and a switch circuit. During a sampling cycle, the switch circuit connects a pre-defined voltage and reference voltages to the pre-sampling capacitor circuit, disconnects the pre-sampling capacitor circuit from an input port of the operational amplifier and the sampling capacitor circuit, disconnects an output port of the operational amplifier from the sampling capacitor circuit, and connects a voltage input to the sampling capacitor circuit. During a conversion cycle, the switch circuit connects the pre-sampling capacitor circuit to the sampling capacitor circuit, disconnects the pre-defined voltage and the reference voltages from the pre-sampling capacitor circuit, connects the pre-sampling capacitor circuit to the input port of the operational amplifier, connects the output port of the operational amplifier to the sampling capacitor circuit, and disconnects the voltage input from the sampling capacitor circuit.