A delta sigma modulator circuit comprises a forward circuit path including a first integrator stage and an analog-to-digital converter (ADC) circuit, wherein a transfer function of the forward circuit path includes a signal gain element of m, wherein m is a positive integer; an input path to the first integrator stage, wherein a transfer function of the input path includes a signal gain element of l/m; and a feedback circuit path operatively coupled to an output of the ADC circuit and an inverting input of an op amp of the first integrator stage, wherein the feedback circuit path includes at least a first digital-to-analog converter (DAC) circuit and a transfer function of the feedback circuit path includes a signal gain element of l/m.

A delta sigma modulator circuit comprises a forward circuit path including a first integrator stage and an analog-to-digital converter (ADC) circuit, wherein a transfer function of the forward circuit path includes a signal gain element of m, wherein m is a positive integer; an input path to the first integrator stage, wherein a transfer function of the input path includes a signal gain element of l/m; and a feedback circuit path operatively coupled to an output of the ADC circuit and an inverting input of an op amp of the first integrator stage, wherein the feedback circuit path includes at least a first digital-to-analog converter (DAC) circuit and a transfer function of the feedback circuit path includes a signal gain element of l/m.

Embodiments of sigma-delta analog-to-digital converter (ADC) circuits and a microphone circuit are disclosed. In an embodiment, a sigma-delta ADC circuit includes a pair of operational transconductance amplifiers (OTAs), a filter connected to the pair of OTAs, a quantizer connected to the filter, a differential digital-to-analog converter (DAC) connected to the quantizer, and a bias compensation circuit configured to measure a biasing condition of a first OTA of the pair of OTAs and to apply the biasing condition of the first OTA to a second OTA of the pair of OTAs to reduce Total Harmonic Distortion Plus Noise (THD+N) in the sigma-delta ADC circuit. An output of a microphone and a differential output of the differential DAC are inputted into input terminals of the pair of OTAs.

Embodiments of multi-mode sigma-delta analog-to-digital converter (ADC) circuits and a microphone circuit are disclosed. In an embodiment, a multi-mode sigma-delta ADC circuit includes a pair of operational transconductance amplifiers (OTAs), a filter connected to the pair of OTAs, a quantizer connected to the filter, a differential digital-to-analog converter (DAC) connected to the quantizer, and a controller configured to switch the multi-mode sigma-delta ADC circuit between a single-ended operational mode, a pseudo differential operational mode, and a full differential operational mode to improve common mode rejection (CMR) performance by controlling the pair of OTAs. An output of a microphone and a differential output of the differential DAC are inputted into input terminals of the pair of OTAs.

This application relates to analogue-to-digital converters (ADCs). An ADC 200 has a first converter (201) for receiving an analogue input signal (AIN) and outputting a time encode signal (DT), such as a pulse-width-modulated (PWM) signal, based on input signal and a first conversion gain setting (GIN). In some embodiments the first converter has a PWM modulator (401) for generating a PWM signal such that the input signal is encoded by pulse widths that can vary continuously in time. A second converter (202) receives the time encoded signal and outputs a digital output signal (DOUT) based on the time encoded signal (DT) and a second conversion gain setting (GO). The second converter may have a first PWM-to-digital modulator (403). A gain allocation block (204) generates the first and second conversion gain settings based on the time encoded signal (DT). The gain allocation block (204) may have a second PWM-to-digital modulator (203) which may be of lower latency and/or lower resolution that the first PWM-to-digital modulator (403).

This application relates to analog-to-digital converters (ADCs). An ADC 200 has a first converter (201) for receiving an analog input signal (AIN) and outputting a time encode signal (DT), such as a pulse-width-modulated (PWM) signal, based on input signal and a first conversion gain setting (GIN). In some embodiments the first converter has a PWM modulator (401) for generating a PWM signal such that the input signal is encoded by pulse widths that can vary continuously in time. A second converter (202) receives the time encoded signal and outputs a digital output signal (DOUT) based on the time encoded signal (DT) and a second conversion gain setting (GO). The second converter may have a first PWM-to-digital modulator (403). A gain allocation block (204) generates the first and second conversion gain settings based on the time encoded signal (DT). The gain allocation block (204) may have a second PWM-to-digital modulator (203) which may be of lower latency and/or lower resolution that the first PWM-to-digital modulator (403).

Delta-sigma modulators do not handle overload well, and often become unstable if the input goes beyond the full-scale range of the modulator. To provide overload protection, an improved technique embeds an overload detector in the delta sigma modulator. When an overload condition is detected, coefficient(s) of the delta sigma modulator is adjusted to accommodate for the overloaded input. The improved technique advantageously allows the delta sigma modulator to handle overload gracefully without reset, and offers greater dynamic range at reduced resolution. Furthermore, the coefficient(s) of the delta sigma modulator can be adjusted in such a way to ensure the noise transfer function is not affected.

This application relates to analogue-to-digital converters (ADCs). An ADC 200 has a first converter (201) for receiving an analogue input signal (AIN) and outputting a time encode signal (DT), such as a pulse-width-modulated (PWM) signal, based on input signal and a first conversion gain setting (GIN). In some embodiments the first converter has a PWM modulator (401) for generating a PWM signal such that the input signal is encoded by pulse widths that can vary continuously in time. A second converter (202) receives the time encoded signal and outputs a digital output signal (DOUT) based on the time encoded signal (DT) and a second conversion gain setting (GO). The second converter may have a first PWM-to-digital modulator (403). A gain allocation block (204) generates the first and second conversion gain settings based on the time encoded signal (DT). The gain allocation block (204) may have a second PWM-to-digital modulator (203) which may be of lower latency and/or lower resolution that the first PWM-to-digital modulator (403).

Various embodiments of the present technology may comprise a method and apparatus for an analog-to digital converter (ADC). Methods and apparatus for an ADC according to various aspects of the present invention may operate in conjunction with a reference voltage that varies according to the frequency of a timing signal. By varying the reference voltage according to the frequency of the timing signal, the ADC generates a digital output having a substantially fixed voltage regardless of the frequency of the timing signal.

Various embodiments of the present technology may comprise a method and apparatus for an analog-to digital converter (ADC). Methods and apparatus for an ADC according to various aspects of the present invention may operate in conjunction with a reference voltage that varies according to the frequency of a timing signal. By varying the reference voltage according to the frequency of the timing signal, the ADC generates a digital output having a substantially fixed voltage variation regardless of the frequency of the timing signal.