A feedback divider in a mixed-signal circuit is modulated by a frequency control word controlling a delta-sigma modulator. An accumulated quantization error from the delta-sigma modulator is compared to a residual error in the circuit by a Least-Mean Square (LMS) correlator for gain calibration to adjust for linear errors. Upper bits of the accumulated quantization error access a lookup table to find two outputs of the compensation function that are interpolated between using lower bits of the accumulated quantization error. The interpolated result is an adjustment subtracted from the loop to compensate for non-linear errors. A set of orthogonal kernels is generated from the accumulated quantization error and calibrated using another LMS correlator and inverse transformed to generate updates to the non-linear compensation function in the lookup table. The kernels can be Walsh Hadamard (WH) and the inverse transformer an inverse WH transformer.

A battery-operated device comprises: a first battery cell having a voltage; a second battery cell having a voltage; a first anti-aliasing filter operable to be coupled to the first battery cell; a second anti-aliasing filter operable to be coupled to the second battery cell; an analog-to-digital converter operable to be coupled to the first anti-aliasing filter during a first period of time or the second anti-aliasing filter during a second period of time different than the first period of time; and wherein the second anti-aliasing filter is charged during the first period of time and the first anti-aliasing filter is charged during the second period of time.

A feedback divider in a mixed-signal circuit is modulated by a frequency control word controlling a delta-sigma modulator. An accumulated quantization error from the delta-sigma modulator is compared to a residual error in the circuit by a Least-Mean Square (LMS) correlator for gain calibration to adjust for linear errors. Upper bits of the accumulated quantization error access a lookup table to find two outputs of the compensation function that are interpolated between using lower bits of the accumulated quantization error. The interpolated result is an adjustment subtracted from the loop to compensate for non-linear errors. A set of orthogonal kernels is generated from the accumulated quantization error and calibrated using another LMS correlator and inverse transformed to generate updates to the non-linear compensation function in the lookup table. The kernels can be Walsh Hadamard (WH) and the inverse transformer an inverse WH transformer.

An analog-to-digital converter (ADC) includes an input circuit configured to receive a first analog signal output from a first sensor or a second analog signal output from a second sensor according to an operation mode and a bit stream; a filter configured to filter an output signal from the input circuit; a quantization circuit configured to generate the bit stream from an output signal of the filter; and a digital circuit configured to generate a first digital signal corresponding to the first analog signal or a second digital signal corresponding to the second analog signal by filtering the bit stream, wherein the operation mode includes a first mode selecting the first sensor and a second mode selecting the second sensor, and wherein the digital circuit refers to the second digital signal generated during the second mode to generate the first digital signal during the first mode.

A modulator includes an input circuit having a sampling capacitor, an integration circuit, a quantizer and a D/A converter having a DAC capacitor. The input circuit takes in an analog input voltage in the sampling capacitor in a sampling period, and transfers a charge to the integration circuit in a holding period. The D/A converter takes in an analog potential, to which selection switches are connected in the sampling period based on a digital output of the quantizer, in the DAC capacitor, and subtracts a charge from the integration circuit in the holding period. At this time, since the input circuit and the D/A converter are set so that the holding periods do not overlap with each other, an error caused by the lowering of a feedback factor is suppressed.

A battery powered system includes a voltage level shifter, an anti-aliasing filter, a pair of switches, a unity gain differential buffer, a second pair of switches, and an analog-to-digital converter. The first pair of switches couple the differential output port of the voltage level shifter to the differential input port of the anti-aliasing filter. The second pair of switches couple the differential output port of the anti-aliasing filter to the differential input port of the unity gain differential buffer. The analog-to-digital converter is coupled to the differential output port of the unity gain differential buffer.

An apparatus for dynamic range enhancement (DRE) which receives an input signal and provides a DRE output signal is presented. The apparatus has an error correction circuit to apply an error correction factor to the input signal such that the DRE output signal provided by the apparatus is dependent on the input signal and the error correction factor. The error correction factor is representative of an error generated by the apparatus.

Systems and methods are disclosed for a signal convertor comprising a resistor or current source coupled to a positive virtual ground node and a negative virtual ground node, wherein the resistor or current source is configured to switch from the positive virtual ground node (VGP) to the negative virtual ground node (VGN), wherein the switching of the resistor or current source results in a shaping of the low frequency noise from the resistor.

A battery powered system includes a voltage level shifter, an anti-aliasing filter, a pair of switches, a unity gain differential buffer, a second pair of switches, and an analog-to-digital converter. The first pair of switches couple the differential output port of the voltage level shifter to the differential input port of the anti-aliasing filter. The second pair of switches couple the differential output port of the anti-aliasing filter to the differential input port of the unity gain differential buffer. The analog-to-digital converter is coupled to the differential output port of the unity gain differential buffer.

Described herein is a fractional phase locked loop with sigma-delta modulator (SDM) quantization noise cancellation. The fractional phase includes a digital filter configured to receive an error signal based on a comparison of a reference clock and a feedback clock, a controlled oscillator configured to generate an output clock by adjusting a frequency of the controlled oscillator based on a control signal output by the digital filter, the feedback clock being based on the output clock, a sigma-delta modulator configured to control division of the output clock to generate a divided output clock which includes a sigma-delta modulator quantization noise and a digital-to-time converter configured to receive a cancellation code from an integrator in the sigma-delta modulator and cancel the sigma-delta modulator quantization noise in the divided output clock with the cancellation code to generate the feedback clock.