The present application relates to an EQ circuit, a method of operating it and a system comprising the EQ circuit and an ADC. The EQ circuit has a configurable load section, which is provided for selectively exposing one of a plurality of distinct loads to a reference source connected to a reference voltage signal input of the equalization circuit, and a logic section, which is arranged to accept a state signal from the ADC and to selectively connect one distinct load out of the plurality of distinct loads in response to the state signal. The state signal is indicative of an actual operation state of the ADC.

An analog to digital conversion device according to one or more embodiments may include sequential comparison type analog to digital converters, wherein each of the analog to digital converters converts an analog signal to a digital signal by repeating comparative voltage generation processing to generate a comparative voltage and comparison processing to compare the analog signal with the comparative voltage. Each of the analog to digital converters may include a noise notification part that generates a noise notification signal to give notification of noise production and inputs the noise notification signal to a different one of the analog to digital converters. At start of operation, based on the notification noise signal inputted from the different analog to digital converter, each of the analog to digital converters may be synchronized with the different analog to digital converter performing the comparative voltage generation processing and the comparison processing.

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.

Methods and apparatuses are described herein for metastability error detection and correction in analog-to-digital converters (ADCs). For example, an ADC may comprise a comparator, a register circuit, a first circuit, and a second circuit. The comparator may generate a comparator output signal in response to a sampling clock signal. The register circuit, operatively coupled to the comparator, may process the comparator output signal. The first circuit, operatively coupled to the comparator and the register circuit may generate a plurality of first output bits that include a bit indicating a metastability error on a condition that the metastability error occurred during the bit conversion. The second circuit, operatively coupled to the first circuit, may generate a plurality of second output bits indicating a location of the metastability error. The plurality of second output bits may be sampled using first and second groups in response to the sampling clock signal.

A system and method of analog to digital conversion including an adjustable ADC, FIR filter circuitry, and a noise setting controller. The ADC samples an analog input signal to provide digital samples at a sample rate that is Y times an output rate of output digital values. The FIR filter circuitry includes Y taps with Y corresponding coefficients and is configured to filter the digital samples from the ADC and to provide filtered digital samples at the sample rate. decimation circuitry may be included to decimate the filtered digital samples by Y to provide the output digital values. The noise setting controller provides an adjustment value to the ADC to adjust noise contribution of the digital samples provided by the ADC based on corresponding coefficients of the FIR filter circuitry. The ADC is adjusted to reduce noise contribution of digital samples that correspond with higher FIR filter coefficients.

Examples are disclosed related to analog to digital conversions. One example provides a conversion circuit comprising a first analog-to-digital converter (ADC) configured to convert an analog voltage to generate a first subset of digital output bits from a most significant bit (MSB) to a bit k and a second subset of digital output bits from a bit k?1 to a least significant bit (LSB) of the first ADC. The bit k is between the MSB and the LSB. The first ADC comprises a residual output configured to output a residual voltage of the analog voltage after converting the bit k. The conversion circuit further comprises an amplifier stage connected to the residual output and configured to generate an amplified residual voltage. The conversion circuit further comprises a second ADC connected to the amplifier stage and configured to convert the amplified residual voltage to generate extra digital output bits.

An analog to digital conversion device according to one or more embodiments may include sequential comparison type analog to digital converters, wherein each of the analog to digital converters converts an analog signal to a digital signal by repeating comparative voltage generation processing to generate a comparative voltage and comparison processing to compare the analog signal with the comparative voltage. Each of the analog to digital converters may include a noise notification part that generates a noise notification signal to give notification of noise production and inputs the noise notification signal to a different one of the analog to digital converters. At start of operation, based on the notification noise signal inputted from the different analog to digital converter, each of the analog to digital converters may be synchronized with the different analog to digital converter performing the comparative voltage generation processing and the comparison processing.

A method and apparatus are provided for controlling an SAR ADC by generating a first signal to control sampling of an analog input voltage at a DAC, and then generating a second signal to start a successive approximation sequence at a comparator and SAR engine to convert the analog input voltage to an N-bit digital value, where the successive approximation sequence includes a settling phase for each bit of the N-bit digital value and is controlled to synchronously end in response to a first synchronous clock signal, and also includes a comparison phase for each bit of the N-bit digital value to allow for comparison of the analog input voltage to a reference voltage, where each comparison phase is controlled to synchronously start in response to the first synchronous clock signal and asynchronously end in response to a second asynchronous clock signal that is self-generated by the comparator.

Methods and apparatuses are described herein for metastability error detection and correction in analog-to-digital converters (ADCs). For example, an ADC may comprise a comparator, a register circuit, a first circuit, and a second circuit. The comparator may generate a comparator output signal in response to a sampling clock signal. The register circuit, operatively coupled to the comparator, may process the comparator output signal. The first circuit, operatively coupled to the comparator and the register circuit may generate a plurality of first output bits that include a bit indicating a metastability error on a condition that the metastability error occurred during the bit conversion. The second circuit, operatively coupled to the first circuit, may generate a plurality of second output bits indicating a location of the metastability error. The plurality of second output bits may be sampled using first and second groups in response to the sampling clock signal.

An Analog-to-Digital Converter (ADC) device includes an input interface and conversion circuitry. The input interface is configured to receive an analog input signal. The conversion circuitry is configured to convert the analog input signal into a digital word by performing a sequence of iterations to determine respective bits of the digital word, wherein the sequence (i) progresses in descending order of bit significance of the bits, from a Most Significant Bit (MSB) to a Least Significant Bit (LSB), and (ii) repeats evaluation of a predefined number of Least-Significant Bits (LSBs) of the digital word multiple times, and determining a final value of the digital word by averaging the repeatedly-evaluated LSBs.