Differential clamp circuits configured to recirculate the current in one clamp, either low-side clamp or high-side clamp, from one output of a differential signal to the other output of the differential signal are disclosed. Differential clamp circuits described herein may be particularly suitable for providing programmable clamps at differential outputs of an ADC driver and may be particularly beneficial to implement clamps that are symmetrical around an ADC's input common-mode voltage. Some differential clamp circuit described herein may advantageously present a smaller capacitive load at each output, thus reducing bandwidth degradation of the output stage. Furthermore, differential clamp circuits described herein may operate with only one control voltage, making it easier to limit the output excursions symmetrically around the default common-mode voltage.

Differential clamp circuits configured to recirculate the current in one clamp, either low-side clamp or high-side clamp, from one output of a differential signal to the other output of the differential signal are disclosed. Differential clamp circuits described herein may be particularly suitable for providing programmable clamps at differential outputs of an ADC driver and may be particularly beneficial to implement clamps that are symmetrical around an ADC's input common-mode voltage. Some differential clamp circuit described herein may advantageously present a smaller capacitive load at each output, thus reducing bandwidth degradation of the output stage. Furthermore, differential clamp circuits described herein may operate with only one control voltage, making it easier to limit the output excursions symmetrically around the default common-mode voltage.

A family of current mode analog to digital converters, or TiADC, utilizing methods, circuits, and apparatuses, are disclosed with the following benefits: (1) There are normal and random non-systematic mismatch between devices in silicon manufacturing, that introduce non-linearity in current mode analog to digital converter's, or iADC, reference network. The iADC's linearity is improved by utilizing a thermometer current mode signal conditioning method, SCM. Successive applications of the SCM effectuates a segmented current reference network to function like a thermometer network, which operates based on the function of summation. Having a TiADC with a thermometer reference network, where current segments are summed or accumulated incrementally, would inherently reduce the impact of statistical distribution of component's random mismatch on the iADC's non-linearity. Accordingly, linearity of TiADC can be improved by the square root of the sum of the square of mismatch errors of the number of segmented current references in the thermometer network. (2) speed is improved by operating the TiADC in current mode, which is inherently faster. (3) voltage swings in current mode are small, which enables he iADC to operate at lower power supply voltages. (4) The TiADC can operate in subthreshold and at very low currents, which lower powers consumption. (5) the TiADC is asynchronous. Being clock free, TiADC has lower dynamic power consumption with reduces digital system noise. (6) the signal conditioning method or SCM utilized in TiADC provides concurrent functions of analog differencing and digital comparison. This trait enhances the dynamic response of iADC, wherein the digital output throughput accuracy degrades gradually and not abruptly as a function of increasing frequency of iADC's input signal. (7) No passive devices, such as capacitors or resistors, are required for the TiADC. (8) TiADC can be fabricated on low cost mainstream standard digital CMOS processes.

Single-stage and multiple-stage current-mode Analog-to-Digital converters (iADC)s utilizing apparatuses, circuits, and methods are described in this disclosure. The disclosed iADCs can operate asynchronously and be free from the digital clock noise, which also lowers dynamic power consumption, and reduces circuitry overhead associated with free running clocks. For their pseudo-flash operations, the disclosed iADCs do not require their input current signals to be replicated which saves area, lowers power consumption, and improves accuracy. Moreover, the disclosed methods of multi-staging of iADCs increase their resolutions while keeping current consumption and die size (cost) low. The iADC's asynchronous topology facilitates decoupling analog-computations from digital-computations, which helps reduce glitch, and facilitates gradual degradation (instead of an abrupt drop) of iADC's accuracy with increased input current signal frequency. The iADCs can be arranged with minimal digital circuitry (i.e., be digital-light), thereby saving on die size and dynamic power consumption.

A current comparator including a first comparator configured to generate a first output signal based on a comparison of a first current to at least a second current; a second comparator configured to generate a second output signal based on a comparison of the first current to at least a third current; and a circuit configured to: direct the first current to the first comparator to perform the comparison of the first current to the at least the second current while blocking the first current from being applied to the second comparator; or direct the first current to the second comparator to perform the comparison of the first current to the at least the third current while blocking the first current from being applied to the first comparator.

A family of current mode analog to digital converters, or TiADC, utilizing methods, circuits, and apparatuses, are disclosed with the following benefits: (1) There are normal and random non-systematic mismatch between devices in silicon manufacturing, that introduce non-linearity in current mode analog to digital converter's, or iADC, reference network. The iADC's linearity is improved by utilizing a thermometer current mode signal conditioning method, SCM. Successive applications of the SCM effectuates a segmented current reference network to function like a thermometer network, which operates based on the function of summation. Having a TiADC with a thermometer reference network, where current segments are summed or accumulated incrementally, would inherently reduce the impact of statistical distribution of component's random mismatch on the iADC's non-linearity. Accordingly, linearity of TiADC can be improved by the square root of the sum of the square of mismatch errors of the number of segmented current references in the thermometer network. (2) speed is improved by operating the TiADC in current mode, which is inherently faster. (3) voltage swings in current mode are small, which enables the iADC to operate at lower power supply voltages. (4) The TiADC can operate in subthreshold and at very low currents, which lower powers consumption. (5) the TiADC is asynchronous. Being clock free, TiADC has lower dynamic power consumption with reduces digital system noise. (6) the signal conditioning method or SCM utilized in TiADC provides concurrent functions of analog differencing and digital comparison. This trait enhances the dynamic response of iADC, wherein the digital output throughput accuracy degrades gradually and not abruptly as a function of increasing frequency of iADC's input signal. (7) No passive devices, such as capacitors or resistors, are required for the TiADC. (8) TiADC can be fabricated on low cost mainstream standard digital CMOS processes.

A current comparator including a first comparator configured to generate a first output signal based on a comparison of a first current to at least a second current; a second comparator configured to generate a second output signal based on a comparison of the first current to at least a third current; and a circuit configured to: direct the first current to the first comparator to perform the comparison of the first current to the at least the second current while blocking the first current from being applied to the second comparator; or direct the first current to the second comparator to perform the comparison of the first current to the at least the third current while blocking the first current from being applied to the first comparator.

A method for processing input variables using a processing device including at least two field-effect transistors. Drain-to-source paths of the at least two field-effect transistors are each connected to a first circuit node. The method includes: applying to a gate electrode of the first field-effect transistor a first drive signal which characterizes a first input variable associated with the first field-effect transistor; applying to a gate electrode of the second field-effect transistor a second drive signal which characterizes a first input variable associated with the second field-effect transistor, wherein at least one of the first drive signal and/or the second drive signal has a non-constant amplitude.

A current-mode analog-digital conversion (ADC) circuit directly samples and digitizes an input signal in the current domain; the input signal may be a current signal or a photonic signal. Input capacitors may be coupled to the current source by a series of switches and configured to store a target charge. The target charge may be compared to a reference voltage by comparators of the system to generate digital output. The current-mode ADC circuit may be adapted to flash, successive-approximation, and pipeline architectures, or embodied in a photonic receiver incorporating current-mode ADC circuits configured to sample and digitize photonic signals.

A method for parallel analog in-memory computing is provided. The method includes the following steps: inputting an analog current signal; replicating the analog current signal to form a corresponding replicated current signal, and performing weighted processing of all the replicated current signals to obtain a corresponding set of modulated current signals; and performing weighted accumulated operation of the set of modulated current signals according to Kirchhoff's current law to obtain an output current signal. In the present disclosure, input, processing and output of signals are performed in a pure current domain, and precise replication and output of current signals are achieved, thereby ensuring the output current precision even under the condition of a high line resistance.