Superconductor analog-to-digital converters (ADC) offer high sensitivity and large dynamic range. One approach to increasing the dynamic range further is with a subranging architecture, whereby the output of a coarse ADC is converted back to analog and subtracted from the input signal, and the residue signal fed to a fine ADC for generation of additional significant bits. This also requires a high-gain broadband linear amplifier, which is not generally available within superconductor technology. In a preferred embodiment, a distributed digital fluxon amplifier is presented, which also integrates the functions of integration, filtering, and flux subtraction. A subranging ADC design provides two ADCs connected with the fluxon amplifier and subtractor circuitry that would provide a dynamic range extension by about 30-35 dB.

An analog-to-digital converter includes a switched capacitor circuit, an analog-to-digital conversion circuit, and a constant current circuit. The switched capacitor circuit includes first and second input terminals for a differential input, and is configured to sample an analog voltage of the differential input. The analog-to-digital conversion circuit is connected to output terminals of the switched capacitor circuit, and configured to convert the sampled analog voltage into a digital signal and output the digital signal. The constant current circuit is connected to at least one of the first and second input terminals.

A charge sharing circuit includes a charge source having an accumulated first charge and a charge load having an accumulated second charge, where during a charge sharing interval the second charge is less than the first charge. A charge sharing regulator selectively couples between the charge source and the charge load along a charge sharing path. The charge sharing regulator regulates transfer of a shared amount of charge from the charge source to the charge load during the charge sharing interval.

An apparatus measures a speaker impedance. A DAC converts a known digital input signal to an audio frequency first analog voltage signal. Resistors with known resistance attenuate the first analog voltage signal to generate a current. The known resistance effectively determines the current because the known resistance is high relative to the speaker impedance. The current is sourced into the speaker to generate a second analog voltage signal. The known resistance is sufficiently high to cause the second analog voltage signal to be inaudible as transduced by the speaker. An amplifier amplifies the second analog voltage signal with a known gain to generate a third analog voltage signal. An ADC converts the third analog voltage signal to a digital output signal. A processing element calculates the impedance of the speaker proportional to the digital output signal based on the known digital input signal, the known resistance, and the known gain.

An optical encoder includes an encoding disk and an optical detector disposed to correspond to the encoding disk. The optical detector includes a plurality of optical sensors arranged to form an optical sensor array. The optical detector is provided to receive light. The optical detector includes at least one optical sensor arranged to form at least one sensor array. The width of the sensor array corresponds to an interpolation period of the optical encoder.

An optical encoder includes an encoding disk and an optical detector disposed to correspond to the encoding disk. The optical detector includes a plurality of optical sensors arranged to form an optical sensor array. The optical detector is provided to receive light. The optical detector includes at least one optical sensor arranged to form at least one sensor array. The width of the sensor array corresponds to an interpolation period of the optical encoder.

A charge sharing circuit includes a charge source having an accumulated first charge and a charge load having an accumulated second charge, where during a charge sharing interval the second charge is less than the first charge. A charge sharing regulator selectively couples between the charge source and the charge load along a charge sharing path. The charge sharing regulator regulates transfer of a shared amount of charge from the charge source to the charge load during the charge sharing interval.

A method of operation in an analog-to-digital converter (ADC) includes performing a calibration operation. The calibration operation includes sampling an input analog reference voltage. A sequence of charge sharing transfers is then performed with a charge sharing regulator to transfer an actual amount of charge between a charge source and a charge load based on the input analog reference voltage. The transferred actual amount of charge is compared to a reference charge value corresponding to the reference voltage. A control input to the charge sharing regulator is adjusted to correspondingly adjust charge sharing of a subsequent amount of charge based on the comparing.

An analog-to-digital converter (ADC) including input circuitry to receive an input analog signal having an analog signal level. Sampling circuitry couples to the input circuitry and includes first and second capacitor circuits to sample the received input analog signal. The first and second capacitor circuits exhibit a relative charge imbalance as a result of the sampling that corresponds to the analog signal level. Regulated charge sharing circuitry regulates charge sharing transfers during multiple charge sharing transfer sequences with the first and second capacitor circuits. A digital output generates multiple bit values based on the charge sharing transfer sequences.

An apparatus measures a speaker impedance. A DAC converts a known digital input signal to an audio frequency first analog voltage signal. Resistors with known resistance attenuate the first analog voltage signal to generate a current. The known resistance effectively determines the current because the known resistance is high relative to the speaker impedance. The current is sourced into the speaker to generate a second analog voltage signal. The known resistance is sufficiently high to cause the second analog voltage signal to be inaudible as transduced by the speaker. An amplifier amplifies the second analog voltage signal with a known gain to generate a third analog voltage signal. An ADC converts the third analog voltage signal to a digital output signal. A processing element calculates the impedance of the speaker proportional to the digital output signal based on the known digital input signal, the known resistance, and the known gain.