An apparatus comprises a sigma-delta analog-to-digital converter (ADC) circuit configured to convert an analog input signal to a digital value. The sigma-delta ADC circuit includes a loop filter circuit including at least one loop filter amplifier, a flash ADC circuit including multiple comparators, and a bias control circuit configured to change a biasing of the at least one loop filter amplifier according to outputs of the multiple comparators of the flash ADC circuit.

This invention enables to efficiently improve the signal-to-noise power ratio of a delta-sigma modulator without increasing the operating frequency. A digital modulation device 40 includes: a setting unit 41 that sets mutually different default values for N delta-sigma modulation units 42-1 to 42-N; N delta-sigma modulation units 42-1 to 42-N that input signals for each clock cycle indicated in a first clock signal and then perform delta-sigma modulation on the input signals to output modulated signals including noise signals having values that change in accordance with default values; and a serial output unit 43 that inputs, in order, the modulated signals output by the delta-sigma modulation units 42-1 to 42-N for each clock cycle indicated in a second clock signal, the second clock signal having a clock cycle that is 1/N of the clock cycle of the first clock signal, and then serializes and outputs the modulated signals.

In accordance with an embodiment, a method of operating a switched capacitor circuit includes pre-charging a capacitor using a voltage buffer having an input coupled to an input node of the switched capacitor circuit and an output coupled to the capacitor, coupling the input node to the capacitor, wherein a first charge is collected on the capacitor, and integrating the first charge using an integrator.

A temperature sensor is disclosed. In one aspect, the temperature sensor provides a digital output having a precise degree/code step. For example, each step in the digital output code may correspond to one degree Celsius. In one aspect, a temperature sensor comprises a precision band-gap circuit and a sigma delta modulator (SDM) analog-to-digital convertor (ADC). A bandgap voltage and a PTAT voltage may be provided from the band-gap circuit as an input to the SDM ADC. The SDM ADC may produce an output based on the difference between the PTAT voltage and the bandgap voltage. The temperature sensor may also have logic that outputs a temperature code based on the output of the SDM ADC.

A digital temperature sensor circuit is disclosed. The digital temperature sensor circuit includes a proportional to the absolute temperature (PTAT) current source, generating a PTAT current proportional to absolute temperature; a sigma-delta modulation module, including an integrator, an analog-to-digital conversion unit, and a feedback digital-to-analog conversion unit; the integrator converts the PTAT current into temperature voltage; the analog-to-digital conversion unit compares the temperature voltage with a band gap reference voltage to generate a digital modulation signal with a duty ratio proportional to the temperature; the feedback digital-to-analog conversion unit adjusts the voltage input by the analog-to-digital conversion unit and controls the charging and discharging speed of the integrator; a digital filter, quantizing the digital modulation signal into a digital signal, and outputting the digital signal.

A time constant calibration circuit and method. The circuit comprises a resistor, a capacitor, an amplifier, a first switch and a second switch. The resistance of the resistor and/or the capacitance of the capacitor is variable. A first terminal of the resistor, a first terminal of the capacitor and a first input of the amplifier are coupled to a common node, which is coupleable to a reference current source. A second input of the amplifier is coupleable to a reference voltage. An output of the amplifier is coupled to a second terminal of the resistor and a second terminal of the capacitor. The circuit can perform a calibration process comprising one or more calibration cycles in which the switches route a reference current through the resistor in a first phase and through the capacitor in a second phase. The resistance and/or the capacitance is adjusted between calibration cycles.

A circuit includes a first input terminal, a second input terminal, a third input terminal and an output terminal. A first summation node adds signals at the first and third input terminals. A second summation node subtracts signals at the second and third input terminals. A selector selects between the added signals and subtracted signals in response to a selection signal. The output of the selector is integrated to generate an integrated signal. The integrated signal is compared by a comparator to a threshold, the comparator generating an output signal at the output terminal having a first level and a second level. Feedback of the output signal produces the selection signal causing the selector to select the added signals in response to the first level of the output signal and causing the selector to select the subtracted signals in response to the second level of the output signal.

A receiver system includes an interface between a radio receiver on a radio frequency (RF)-side and a baseband receiver on a baseband (BB)-side. The receiver includes an antenna for receiving radio frequency signals and an analogue-to-digital converter for converting received analogue signals to digital signals. The digital signals are further processed in the baseband receiver by a digital signal processing unit. The analogue-to-digital converter is a sigma-delta converter, which includes a sigma-delta modulator on the RF-side and a decimation filter on the BB-side. The sigma-delta modulator and the decimation filter are connected only by single-bit in-phase (I) and quadrature (Q) streams output lines.

A variety of methods, controllers and electric machine systems are described that facilitate pulsed control of electric machines (e.g., electric motors and generators) to improve the machine's energy conversion efficiency. Under selected operating conditions, the electric machine is intermittently driven (pulsed). The pulsed operation causes the output of the electric machine to alternate between a first output level and a second output level that is lower than the first output level. The output levels are selected such that at least one of the electric machine and a system that includes the electric machine has a higher energy conversion efficiency during the pulsed operation than the electric machine would have when operated at a third output level that would be required to drive the electric machine in a continuous manner to deliver the desired output. In some embodiments, the second output level is zero torque.

A digital lock-in controller for Resonant-type converters with one or more sub-circuits having resonant tanks and one or more flying capacitors connected across the resonant tanks, which comprises an auto-tuner that receives as input Zero-Current Detect (ZCD) signals and implements a tuning algorithm by performing arithmetic operations that ensure Zero-Current Switching (ZCS) operation for all resonant tanks in the converter; a digital hybrid High-Resolution (HR) sequencer that receives as input the switching times commands and generates a pulse-width-modulated signal that is fed into the gates of the converter's switching transistors; a sampling block with time resolution of a single delay-element, for accurately reading of the ZCD sensor's outputs; a governor module for performing all synchronization actions and dictating the operation mode of the controller, based on auxiliary configurations.