There is disclosed herein charge-mode circuitry for use in a comparator to capture a difference between magnitudes of first and second input signals, the circuitry comprising: a tail node configured during a capture operation to receive a charge packet; first and second nodes conductively connectable to said tail node along respective first and second paths; and control circuitry configured during the capture operation to control such connections between the tail node and the first and second nodes based on the first and second input signals such that said charge packet is divided between said first and second paths in dependence upon the difference between magnitudes of the first and second input signals.

According to one example embodiment, an image sensor is configured to operate in a plurality of operation modes. The image sensor includes a pixel array including unit pixels configured to generate an analog image signal from incident light, a readout circuit configured to generate a digital image signal by converting the analog image signal, and a control module configured to generate control signals for controlling operations of the pixel array and the readout circuit according to an operation mode of the image sensor. A first power voltage for driving the image sensor when the operation mode of the image sensor is an image recognition mode for recognizing a body of a user of the image sensor, is lower than a second power voltage for driving the image sensor when the operation mode of the image sensor is an image capture mode for capturing images by the user.

A cyclic analog to digital converter for digitizing an output from a photoplethysmography sensor has a buffer amplifier for setting a voltage of the feedback capacitance. Additionally, digital averaging circuit is preferably provided for averaging the digital output from the cyclic analog to digital converter for the several conversions. Finally, voting logic is additionally provided for declaring the digital bits based on successive comparisons by the one or more comparators.

Analog signal measurement and related circuitry, systems, and methods are disclosed. Circuitry includes timing circuitry configured to assert a first enable signal at a first time and a second enable signal at a second time. The circuitry also includes an operational amplifier circuit configured to enable responsive to the assertion of the first enable signal. The operational amplifier circuit is configured to receive an analog input signal and, if enabled, generate an amplified analog input signal responsive to the analog input signal. The circuitry further includes signal analyzing circuitry configured to enable responsive to the assertion of the first enable signal, compare the amplified analog input signal to one or more threshold values responsive to the assertion of the second enable signal, and generate an alert signal responsive to a determination that the amplified analog input signal falls outside of the one or more threshold values.

Methods and apparatus for adaptively generating a reference voltage (V.sub.REF) for biasing a switch driver and corresponding switch in a digital-to-analog converter (DAC). The adaptive biasing scheme may be capable of tracking process, voltage, and temperature (PVT) of the DAC. An example DAC generally includes a plurality of DAC cells, each DAC cell comprising a current source, a switch coupled in series with the current source, and a switch driver coupled to a control input of the switch, the switch driver being configured to receive power from a first power supply rail referenced to a reference potential node; a regulation circuit comprising a first transistor coupled between the reference potential node for the DAC and the switch driver in at least one of the plurality of DAC cells; and a V.sub.REF generation circuit coupled to the regulation circuit and configured to adaptively generate a V.sub.REF for the regulation circuit.

A semiconductor circuit includes: an analog circuit that inputs a measured signal; and a digital circuit that outputs a digital output signal. The analog circuit includes: a correction element group including one or more correction elements each for correcting an offset that is an amount of shift caused by a variation in characteristics of the analog circuit to occur in a path for transmitting the measured signal; and a test element group including one or more test elements for testing the one or more correction elements. The digital circuit tests the correction element group using the test element group.

In a system for converting digital data into a modulated optical signal, an electrically controllable device having M actuating electrodes provides and optical signal that is modulated in response to binary voltages applied to the actuating electrodes. A digital-to-digital converter provides a mapping of input data words to binary actuation vectors for M bits and supplies the binary actuation vectors as M bits of binary actuation voltages to the M actuating electrodes, where M is larger than the number of bits in each input data word. The digital-to-digital converter maps each digital input data word to a binary actuation vector by selecting a binary actuation vector from a subset of binary actuation vectors available to represent each of the input data words.

An analog-to-digital circuit that digitizes an analog voltage. The analog-to-digital circuit includes plural comparators functionally connected to form a tree that has levels i, and each level i has branches j, and an encoder connected to the plural comparators and configured to generate a digitized value of an input analog voltage. Each comparator from a level i has first and second outputs, and each of the first and second outputs is electrically connected to an input of different comparators from a next level i+1 of the tree.

An analog-to-digital converter for an image sensor comprises a counter circuit to generate a respective counter bit in response to a counter state of the counter circuit, and a storage circuit for storing a respective storage state in response the respective counter bit. The converter further comprises a comparator circuit for generating a level of a comparison signal, and a synchronization circuit to generate a write control signal for controlling the storing of the respective storage state in the respective storage cell. The counter circuit is configured to change the counter state, when a first edge of a cycle of the clock signal is applied to the counter circuit, and to generate the write control signal, when a second edge of the cycle of the clock signal being subsequent to the first edge of the cycle of the clock signal is applied to the synchronization circuit.

A reference buffer has many legs each with an upper transistor, a lower transistor, and a resistor or current source as a tail device in series. The source or emitter of the upper (lower) transistor generates an upper (lower) reference voltage. This source follower transistor configuration has a low output impedance and high current. The gate or base of the upper (lower) transistors are driven by a first (second) control node. A control leg has an upper transistor, a lower transistor, and a tail device in series. The source and gate, or emitter and base, are connected together for the upper and lower transistors and generate the upper and lower control nodes. Alternately, the gate or base of the upper (lower) transistor is driven by an op amp receiving an upper (lower) bandgap voltage and the upper (lower) control node as negative feedback.