Abstract: An AD conversion circuit and a solid-state imaging apparatus reduce the occurrence of errors in encoding a lower phase signal while securing a degree of freedom of selection of a count clock. A detection circuit performs an operation of detecting logic states of m (m is a natural number of 2 or more) lower phase signals in a signal group that a plurality of lower phase signals latched by the latch unit is arranged, while selecting the m lower phase signals in a predetermined order so that the order thereof becomes the same as the order of the signal group and outputs a state detection signal at the time of detecting that the logic states of the m lower phase signals are in a predetermined logic state in the detection operation. The predetermined order is defined depending on a predetermined signal and an encoding method.

Abstract: An apparatus for acquiring an i-bit digital code by a first stage AD conversion and a j-bit digital code by a second stage AD conversion includes a comparing unit which compares a reference signal and an analog signal in the first stage AD conversion; and an amplifying unit for outputting an amplified residual signal acquired by amplifying a difference between the analog signal and an analog signal corresponding to the i-bit digital code. The comparing unit compares the amplified residual signal and the reference signal in the second stage AD conversion.

Abstract: The invention provides a testing apparatus. In one embodiment, the testing apparatus receives a plurality of bit signals output by an analog-to-digital converter, and comprises a plurality of frequency counters and a comparison module. The frequency counters respectively calculate a plurality of transition frequencies of the values of the bit signals. The comparison module respectively compares the transition frequencies with a plurality of ideal transition frequencies to obtain a plurality of error frequencies. The performance analysis module estimates a performance value of the analog-to-digital converter according to the error frequencies.

Abstract: An AD conversion circuit may include: a reference signal generation unit; a comparison unit; a clock generation unit; a latch unit; a counting unit; and an encoding unit including a detection circuit and an encoding circuit, the detection circuit performing a first detection operation of detecting logic states of n lower phase signals in a signal group that a plurality of lower phase signals latched in the latch unit are arranged in the same order as those of the signal group when the plurality of lower phase signals output from the clock generation unit are arranged to be the signal group the detection circuit outputting a state detection signal when the logic state of the n lower phase signals is detected to be a predetermined logic state in the first detection operation, the encoding circuit performing encoding based on the state detection signal output from the detection circuit.

Abstract: An analog-to-digital converter (ADC) comprises a plurality of time-interleaved integrating ADCs having feedback from an integrated output signal. In variations, the time-interleaved integrating ADCs have feedback compensation from at least one measure of quantization error. The time-interleaved integrating ADCs may also share a single comparator and may also share a single current source.

Abstract: In at least one example embodiment, a counter circuit includes a latch stage configured to generate a latch stage output clock based on a first rising edge of an enable signal, a state of a counter clock at a previous falling edge of the enable signal, and a state of the output clock at the previous falling edge of the enable signal such that the latch stage output clock and the counter clock have a different state if the state of the counter clock at the previous falling edge and the state of the output clock at the previous falling edge are the same and such that the latch stage output clock and the counter clock have a same state if the state of the counter clock at the previous falling edge and the state of the output clock at the previous falling edge are different.

Abstract: Circuits, methods, and apparatus are described that provide calibration of column-parallel analog-to-digital converters (ADCs) in image processing contexts only once per frame (or less frequently) to reduce column-wise noise. For example, the column ADCs are calibrated during an inter-frame time interval, like a vertical blanking interval. In some embodiments, calibration data for the column ADCs for a calibration period is stored at the digital block for use in processing row data from the column ADCs. In other embodiments, calibration data for the column ADCs for the calibration period is stored at column ADCs in a local memory for local correction of the pixel data prior to being read out to the digital block for processing. In certain embodiments, techniques, such as differential ADC architectures, are used to mitigate row-wise noise in context of the frame-wise calibration.

Abstract: A current sensing circuit includes a current sensing unit, a feedback control unit and a digital output unit. The current sensing unit senses a current and produces a pulse signal according to at least one reference signal and at least one feedback signal. The current sensing unit includes a first capacitor set and a second capacitor set. The current sensing unit selects at least one capacitor in the first capacitor set and at least one capacitor in the second capacitor set according to the current value so as to adjust the precision of the current sensing circuit. The feedback control unit is coupled to the current sensing unit and produces the feedback signals according to a clock signal and the pulse signal. The digital output unit is coupled to the current sensing unit and outputs a digital signal according to the pulse signal.

Abstract: In a reference signal comparison AD conversion scheme, a reference signal SLP_ADC and each of P and D phases of a pixel signal voltage VX are compared. A count clock CKcnt1 is counted based on the comparison result. The counting result data is converted into signal data Dsig, i.e., the difference between the P and D phases, which is also subjected to CDS. At this time, the n-bit AD conversion is performed on each of the P and D phases of the pixel signal voltage VX, followed by summation for digital integration. This prevents any possible detrimental effects that may be caused by summation in the analog domain. Although the signal data becomes W times greater, noise will likely become ?W times greater. This alleviates the problem of random noise resulting from AD conversion such as quantizing noise and circuit noise that do not exist in the analog domain, thus reducing the noise.

Abstract: A main digital-to-analog converter (DAC) receives at least one input and generates an adjusted input. A SAR unit generates a code for controlling the main DAC based on a comparison output of a comparing unit that receives the adjusted input. A reference generator, under control of the generated code, generates at least one reference voltage, which is then forwarded to the comparing unit in each corresponding cycle for defining a search range of each cycle, wherein an absolute value of the reference voltage of a latter cycle is less than the reference voltage of a former cycle such that the search range of the latter cycle is smaller than the search range of the former cycle, and search ranges of all the cycles are centered at a base voltage.

Abstract: A single slope AD converter circuit includes a comparator that compares a ramp voltage varying with a predetermined slope as time elapses with an analog input voltage, a counter that counts a predetermined clock in parallel with the comparing process of the comparator, and a controller that outputs a clock count value corresponding to elapsed time when the ramp voltage is smaller than the analog input voltage, as an AD converted first digital value. The comparator compares the ramp voltage with a predetermined first reference voltage, the counter counts the clock in parallel with the comparing process, and the controller outputs the clock count value corresponding to the elapsed time as an AD converted second digital value.

Abstract: A successive approximation register switched capacitor analog to digital converter utilizes a high frequency clock for controlling comparator reset switches and a clock distribution block to operate at lower sample rates. The successive approximation cycles are clocked with the high frequency clock so that the reset switches stay within the leakage limit irrespective of the sample rate but the end of conversion signal is delayed to mimic the slower sample rate.

Abstract: A voltage converter for converting an analog input signal into a digital signal is provided. The pulse width of the digital signal is relative to the voltage level of the analog input signal. The voltage converter includes a comparator and a feedback module. After comparing the analog input signal and an analog feedback signal, the comparator generates the digital signal. When the analog input signal is higher than the analog feedback signal, the digital signal has a first voltage level. When the analog input signal is lower than the analog feedback signal, the digital signal has a second voltage level, which is different from the first voltage level. Based on the digital signal, the feedback module adjusts the analog feedback signal toward the analog input signal.

Abstract: To provide a semiconductor device including an A/D converter circuit that is capable of performing A/D conversion with high accuracy and high resolution and that can be reduced in size. One loop resistance wiring is shared by a plurality of power supply switches and a plurality of output circuits, and a reference voltage having a triangular (step-like) wave generated using the resistance wiring and the plurality of power supply switches is utilized. Thus, high-accuracy digital signals can be obtained using such an A/D converter circuit that can be reduced in size as an output circuit, without using a complicated circuit structure. Further, the number of constituent elements of the A/D converter circuit is small, whereby in the case of providing A/D converter circuits in parallel, variation between the A/D converter circuits can be made small.

Abstract: An analog-digital converter includes: comparators disposed to correspond to analog signals which are converted into digital signals and configured to compare a voltage value of the analog signal, which is converted into the digital signal, with a voltage value of a predetermined reference signal; counters disposed to correspond to the comparators and configured to count a count value at the time point when the comparison process of the corresponding comparator is finished; and a determiner configured to determine a time point when all the comparators finish their comparison processes.

Abstract: An analog-to-digital converter including a comparator configured to compare a pixel signal received at a first input terminal of the comparator with a ramp signal received at a second input terminal of the comparator and generate a comparison signal as a result of the comparison; and a ramp signal supply circuit configured to provide the ramp signal to the comparator, wherein the ramp signal supply circuit generates a first signal as part of the ramp signal in response to the comparison signal and a first clock signal being received at the ramp signal supply circuit, wherein a slope of the first signal sequentially changes until the comparison signal makes a transition from one logic level to another and, after the transition, the ramp signal supply circuit generates a second signal as part of the ramp signal, wherein a slope of the second signal sequentially changes, wherein the slope of the second signal is opposite the slope of the first signal.

Abstract: A solid-state imaging device comprises a pixel array; a reference signal generation unit operable to generate a reference signal that changes monotonically for a predetermined period in a horizontal period; a comparator operable to compare the level of a pixel signal with the level of a reference signal; a counter operable to count input clock pulses; a memory operable to store the number of counts counted by the counter as a digital value; and a timing control unit operable to generate a clock that is to be input into the counter, and change frequency of the clock that is to be input into the counter based on external input data.

Abstract: A comparator is provided. In one embodiment, a method of operating a comparator comprises providing a bias current (920); comparing an input signal and a reference signal to determine a difference signal and an inverted difference signal (930); latching the difference signal and the inverted difference signal to generate a first and second latched signals (950); generating a control signal using at least the first and second latched signals (970); and controlling the bias current in response to the control signal (980), wherein the comparing the input signal and the reference signal (930) is activated and deactivated in response to the controlling the bias current (980).

Abstract: An integrated AD converter includes: a comparator comparing an input voltage with a reference voltage with a ramp waveform whose voltage value linearly changes with time; a high-bit counter triggered by inversion of an output signal of the comparator to start or stop an operation of counting for every cycle of a main clock signal; a time quantizer latching phase information at a timing at which the output signal is inverted using a plurality of clock signals including main clock signals of different phases, and decodes a value of the latched phase information to thereby output lower bits with a resolution higher than a clock cycle; and a regulating unit synchronizing the output signal with the main clock signal, and determines timings of starting and stopping the operation of the high-bit counter and a value for latching the phase information of the main clock signal using a signal resulting from the synchronization.

Abstract: A DA conversion device includes the following elements. A higher-bit current source cell portion includes uniformly weighted higher-bit current source cells to generate an identical constant current. A lower-bit current source cell portion includes a lower-bit current source cells that are weighted to generate 1/two-to-the-power-of-certain-numbers constant currents. A constant current source selection controller includes a lower-bit controller having a scaler that uses clocks scaled down to 1/two-to-the-power-of-certain-numbers to select the lower-bit current source cells, and a higher-bit controller having shift registers and using a signal indicating a carry bit or a borrow bit used in the lower-bit controller to sequentially activate shift outputs of the shift registers, and uses the shift outputs to select the higher-bit current source cells. Constant current outputs of the selected current source cells are added and output so that an output current corresponding to the digital input signal is obtained.

Abstract: A disclosed AD conversion circuit includes a holding portion storing sequence information, signal selection information and time information; a sequencing counter to be initialized by receiving a timing signal output at a predetermined period and counting upon receipt of a matching signal to obtain a sequencing counter count value; a time period counter to be initialized by receiving the timing signal or the matching signal and counting a time period counter count value; a comparator generating the matching signal when the time information matches the time period counter count value after comparison by referring to the sequence information using the sequencing counter count value; a selecting portion selecting analog signals of one type corresponding to the signal selection information obtained by referring to the sequence information using the sequencing counter count value out of analog signals of various types; and an AD converter converting the selected analog signals.

Abstract: Disclosed is an analog-digital converter which includes a pre-amplifier configured to output a comparison result between a sampled analog input signal and a reference signal and to control a power supply operation in response to a power control signal; a digital signal processor configured to generate a digital signal based on the comparison result; a power controller configured to generate an amplifier operation clock signal for controlling the pre-amplifier; and a counter configured to count the number of falling edges of the amplifier operation clock signal and to detect a power interruption point of time of the pre-amplifier according to the counted falling edge number. The power controller generates the power control signal for interrupting a power to be supplied to the pre-amplifier when the power interruption point of time of the pre-amplifier is detected.

Abstract: In a double data rate (DDR) counter and counting method used in, for example, an analog-to-digital conversion in, for example, a CMOS image sensor and method, a first stage of the counter generates a least significant bit (LSB) of the value in the counter. The counter includes at least one second stage for generating another bit of the value in the counter. An input clock signal is applied to a data input of the first stage and a clock input of the second stage.

Abstract: An A/D converter includes: a first comparator that compares an input signal, with a first reference signal which is a ramp wave having a predetermined polarity, and that when the input signal matches the first reference signal, reverses an output signal thereof; a second comparator that compares the input signal, with a second reference signal which is a ramp wave having a different polarity from the first reference signal, and that when the input signal matches the second reference signal, reverses an output signal thereof; and a counter capable of counting up so as to measure the comparison times taken by the first comparator and second comparator, wherein when either of the output signal of the first comparator and the output signal of the second comparator is first reversed, the counter ceases a counting action.

Abstract: A system and method are provided for adaptively controlling timing in SAR ADC of a sampled analog signal within a conversion period. A state machine maintains a set of SAR states including a sampling state and a plurality of bit conversion states. A reference generator generates a quantization level reference for each of the bit conversion states within a parametric settling time thereof. A comparator compares the sampled analog signal with the quantization level reference over a parametric propagation time for determining a hit value for each hit conversion state. A clock generator adaptively defines signals for clocking the state machine and comparator for each SAR state, thereby adaptively delaying bit determination in each bit conversion state by an integration period not less than the settling time, while adaptively delaying quantization level reference generation for a next bit conversion state by a regeneration period not less than the propagation time.

Abstract: A ramp section generates a reference signal. A comparison section compares an analog signal to the reference signal, and terminates a comparison process at a timing at which the reference signal has satisfied a predetermined condition for the analog signal. A main count section performs a count operation and outputs a count value. A latch section latches a second count value at a second timing related to the end of the comparison process corresponding to a second analog signal after latching a first count value at a first timing related to the end of the comparison process corresponding to a first analog signal. A column count section sequentially counts values of bits constituting the second count value retained in the latch section after an initial value has been set on the basis of values of bits constituting the first count value retained in the latch section.

Abstract: There are provided an A/D conversion circuit in which a counter is made to be capable of performing counting at both edges of a clock, up/down count values can be switched while the up/down count values are held, and the duty of the counting operation is difficult to be distorted even with the both-edge counting, a solid-state image sensor, and a camera system. An ADC 15A is configured as an integrating-type A/D conversion circuit using a comparator 151 and a counter 152. The counter 152 has a function of switching a count mode from an up count to a down count and from a down count to an up count while a value is held, a function of performing counting at both rising and falling edges of an input clock CK at a frequency two times as high as that of the input clock, and a function of latching the input clock CK in accordance with an output signal of the comparator 151 and setting non-inverted or inverted data of the latched data to be data of an LSB.

Abstract: A solid state imaging device includes: an AD conversion section having a comparing section, which receives a reference signal from a predetermined reference signal generating section and which compares the reference signal with an analog signal to be processed, and a counter section, which receives a count clock for AD conversion and performs a count operation on the basis of a comparison result of the comparing section, and acquiring digital data of the signal on the basis of output data of the counter section; a count operation period control section controlling an operation period of the counter section on the basis of the comparison result; and a driving control section controlling the reference signal generating section and the AD conversion section such that for the signal to be processed, data of upper N?M bits is acquired in first processing and data of lower M bits is acquired in second processing.

Abstract: A row scanner selects an arbitrary row in an pixel array unit. Per-column AD converters separately convert voltage signals respectively outputted from a column of a plurality of unit pixels in the selected arbitrary row into digital signals. A column scanner sequentially outputs the digital signals by a column-scanning operation thereof. An AD conversion result adjuster judges whether or not the digital signals reach a predetermined judgment value or the status equivalent to the digital signals reaching the predetermined judgment value is generated, and fixes the digital signals to digital pixel values set in accordance with the predetermined judgment value when a result of the judgment is positive.

Abstract: A duty correction circuit includes: a C-element including a first input and a second input; and an inverter connected to the second input of the C-element, wherein the C-element obtains an output of a logic “1” when both inputs are the logic “1”, obtains an output of a logic “0” when both inputs are the logic “0”, and maintains the output to a previous state in other conditions, and complementary clocks having a phase difference of an approximately half cycle are inputted to the first input of the C-element and the inverter respectively.

Abstract: To provide a semiconductor device including an A/D converter circuit that is capable of performing A/D conversion with high accuracy and high resolution and that can be reduced in size. One loop resistance wiring is shared by a plurality of power supply switches and a plurality of output circuits, and a reference voltage having a triangular (step-like) wave generated using the resistance wiring and the plurality of power supply switches is utilized. Thus, high-accuracy digital signals can be obtained using such an A/D converter circuit that can be reduced in size as an output circuit, without using a complicated circuit structure. Further, the number of constituent elements of the A/D converter circuit is small, whereby in the case of providing A/D converter circuits in parallel, variation between the A/D converter circuits can be made small.

Abstract: An analog-to-digital converter that converts an analog input signal into a digital signal includes a comparator configured to compare a reference signal with an input signal and, if the input signal matches the reference signal, inverts an output; a counter configured to count a comparison time of the comparator; a control circuit configured to monitor the output of the comparator; a voltage generating circuit configured to generate, if a monitoring result obtained by the control circuit indicates that the output of the comparator is at a predetermined level, a direct current voltage in accordance with the monitoring result; and an analog adder configured to add the voltage generated by the voltage generating circuit to the input signal and supply a sum signal to an input terminal of the comparator.

Abstract: A current sensing circuit including a current sensing unit, a feedback control unit, and a digital output unit is provided. The current sensing unit senses a current and generates a pulse signal according to at least one reference signal and at least one feedback signal. The feedback control unit is coupled to the current sensing unit and generates the at least one feedback signal according to a clock signal and the pulse signal. The digital output unit is coupled to the current sensing unit and outputs a digital signal according to the pulse signal. The digital output unit counts an amount of pulses of the pulse signal in a predetermined time period to output the digital signal, wherein the amount of pulses is positively correlated with a value of the current.

Abstract: In one embodiment, a method receives an analog input voltage. The method also receives a threshold from a plurality of thresholds. A comparator performs a comparison of the input voltage with the received threshold and outputs an output value based on the comparison of the analog input voltage with the received threshold. The output value is for converting the analog input voltage to a digital value. The method determines if the threshold should be adjusted based on the comparison and adjusts the threshold when it is determined the threshold should be adjusted.

Abstract: A solid-state imaging device comprises a pixel array; a reference signal generation unit operable to generate a reference signal that changes monotonically for a predetermined period in a horizontal period; a comparator operable to compare the level of a pixel signal with the level of a reference signal; a counter operable to count input clock pulses; a memory operable to store the number of counts counted by the counter as a digital value; and a timing control unit operable to generate a clock that is to be input into the counter, and change frequency of the clock that is to be input into the counter based on external input data.

Abstract: An analog to digital converter (ADC) includes a clock control unit supplying a predetermined clock signal corresponding to luminance among a plurality of clock signals having different frequencies; and a signal conversion unit comparing a ramp signal with an inputted pixel signal to generate a comparison result signal. The ADC performs counting corresponding to the predetermined clock signal supplied by the clock control unit and stores a count value counted at a time of the generating of the comparison result signal.

Abstract: An information processing apparatus, includes: a plurality of processor means respectively including storage means for storing analog information and comparison means for comparing analog information stored in the storage means with an inputted reference analog value; input means for inputting the reference analog value to the plurality of processor means while changing the reference analog value in synchronization with a clock signal; and counter means for updating a count value in synchronization with the clock signal and outputting the count value when the analog information and the reference analog value become consistent at a corresponding comparison means.

Abstract: In general, a method includes comparing a first input signal with a second input signal to produce an output signal. The first input signal corresponds to an amount of light detected by a sensor, and the second input signal corresponds to an aggregated value of the output signal. The method may also include aggregating the output signal in a digital accumulator and converting a digital signal from an output of the digital accumulator to an analog signal.

Abstract: An analog-to-digital converter (ADC) within an image sensor includes a comparator comparing a ramp signal with an image signal, and a counter generating a count result in response to the comparison by counting a clock during a counting interval. The ADC determines whether a first counting interval for the counter is less than a reference interval, and if the first counting interval is less than the reference interval the counting interval is a first counting interval, else the counting interval is a second counting interval.

Abstract: Methods for reading a data location coupled to an electrical conductor. A counter receives a signal from an analog-to-digital converter coupled to the electrical conductor. The counter produces two or more counts, and in some embodiments, the counts are based in part on a variable reference voltage. An interfuser may be coupled to an output of the counter. The interfuser receives the two or more counts from the counter and reads data conveyed by the data location based on the two or more counts.

Abstract: An exemplary embodiment of the present invention is an A/D conversion device including: a sample-and-hold circuit that holds an analog input voltage; a sequential conversion register that stores a digital value corresponding to a threshold; a D/A converter that generates an analog voltage corresponding to the digital value stored in the sequential conversion register; a comparator that compares an analog voltage output from the sample-and-hold circuit with an analog voltage obtained from the D/A converter, and outputs a comparison result; a comparison result counter that outputs a determination result according to a count number counted based on the comparison result; and a control circuit that performs control for switching from the comparator function to the A/D conversion function, based on the determination result. During operation of the A/D conversion function, the sequential conversion register sequentially converts the analog voltage held in the sample-and-hold circuit into a digital value.

Abstract: Systems, methods, and devices for obtaining data from a data location. The method may include generating a first value by sensing a data location under a first condition and generating a second value by sensing the data location under a second condition. The method may further include combining the first value with the second value to identify data conveyed by the data location.

Abstract: An integrating A/D converter includes: a comparator comparing an input voltage to a reference voltage having a ramp waveform, a voltage value of which linearly varies with time; a higher-order bit counter starting operation or stopping operation triggered by inversion of an output signal of the comparator and outputting higher order bits by performing counting in a cycle of a clock signal; and a time-to-digital converter latching phase information of the clock signal corresponding to plural signals obtained by delaying an output signal of the comparator and decoding the latched values to output lower order bits having higher resolution than the clock cycle.

Abstract: An A/D converter suitable for use in a system in which the signal power of noise increases with the signal power of the signal, such as an imaging system, utilizes a variable quantization system for converting analog signals into digital signals. The variable quantization is controlled so that at low signal levels the quantization is similar or identical to conventional A/D converters, while the quantization level is increased at higher signal levels. Thus, higher resolution is provided at low signal levels while lower resolution is produced at high signal levels.

Abstract: A digital double sampling method, a related complementary metal oxide semiconductor (CMOS) image sensor, and a digital camera comprising the CMOS image sensor are disclosed. The method includes generating first digital data corresponding to an initial voltage level apparent in a pixel in response to a reset signal, inverting the first digital data, outputting a detection voltage corresponding to image data received from outside of the CMOS image sensor, and counting in synchronization with a clock signal, starting from an initial value equal to the inverted first digital data, and for an amount of time responsive to a voltage level of the detection voltage.

Abstract: In a double data rate (DDR) counter and counting method used in, for example, an analog-to-digital conversion in, for example, a CMOS image sensor and method, a first stage of the counter generates a least significant bit (LSB) of the value in the counter. The first stage includes a first clock input and is edge-triggered on one of the rising and falling edges of a signal applied at the first clock input. The counter includes at least one second stage for generating another bit of the value in the counter. The second stage includes a second clock input and is edge-triggered on the other of the rising and falling edges of a signal applied at the second clock input.

Abstract: An information processing apparatus, includes: a plurality of processor means respectively including storage means for storing analog information and comparison means for comparing analog information stored in the storage means with an inputted reference analog value; input means for inputting the reference analog value to the plurality of processor means while changing the reference analog value in synchronization with a clock signal; and counter means for updating a count value in synchronization with the clock signal and outputting the count value when the analog information and the reference analog value become consistent at a corresponding comparison means.

Abstract: An electronic apparatus includes: an AD conversion section that has a comparing section, which receives a reference signal whose level changes gradually from a reference signal generating section that generates the reference signal and which compares the reference signal with an analog signal to be processed, and a counter section, which receives a count clock for AD conversion and performs a count operation on the basis of a comparison result of the comparing section, and that acquires digital data of the signal to be processed on the basis of output data of the counter section; a count operation period control section that controls an operation period of the counter section in each processing period on the basis of the comparison result of the comparing section; and a driving control section that controls the reference signal generating section and the AD conversion section.

Abstract: It is an object of the present invention to provide a solid-state imaging device for enhancing accuracy of AD conversion and active switching of up-counting and down-counting in the asynchronous counter without limiting the AD conversion frequency. The solid-state imaging device according to the present invention includes an asynchronous counter having an up-counting mode in which up-counting is performed, a down-counting mode in which down-counting is performed, and a holding mode for switching operation settings between the up-counting and the down-counting while maintaining a count value held in the asynchronous counter.

Abstract: An analog-to-digital converter (ADC) is provided. The ADC includes a variable oscillator, a frequency divider, a clock circuit, and a counter. The variable oscillator is coupled to a sensor and configured to generate an oscillating signal based on a measurement generated by the sensor. The frequency divider is coupled to the variable oscillator and configured to divide a frequency of the oscillating signal. The clock circuit is configured to generate a clock signal at a defined frequency. The counter is coupled to the frequency divider and to the clock and is configured to generate a bit stream representative of a first number of periods of the clock signal during a second number of periods of the divided oscillating signal.