A current to digital converter circuit has an integrator amplifier with an input adapted to receive a current signal and an output adapted to provide a voltage signal as a function of an integration of the current signal, a quantizer circuit with an input which is coupled to the output of the integrator amplifier and with an output adapted to provide a binary result signal as a function of a comparison of the voltage signal with at least a first reference voltage signal, a digital-to-analog converter circuit which is coupled in a switchable manner as a function of the binary result signal to the input of the integrator amplifier, and a controlled current source which is coupled to the output of the integrator amplifier via a first switch which is controlled as a function of the binary result signal such that an auxiliary current is supplied to the output of the integrator amplifier.

The number of bits in the quantizer can be decoupled from the number of bits in the feedback digital-to-analog converter (DAC). A delta-sigma analog-to-digital converter circuit can include a first quantizer to generate an output having a first number of bits and a second quantizer coupled to an output of the first quantizer, where the second quantizer can receive the output of the first quantizer and generate an output having a second number of bits. The feedback DAC can be coupled to the second quantizer to receive a representation of the output of the second quantizer, where the output of the feedback digital-to-analog converter circuit has the second number of bits. These techniques can reduce the area of the feedback DAC, e.g., 4 or 5 bits, and the techniques can achieve a higher maximum stable amplitude (MSA) because it is effectively a second order loop.

An exemplary quantizer includes a multi-bit analog-to-digital converter (ADC) and a first digital-to-analog converter (DAC) feedback circuit. The multi-bit ADC has an internal DAC associated with comparison of each sampled analog input of the multi-bit ADC. The multi-bit ADC converts a currently-sampled analog input into a first digital output. A first noise-shaped truncation output is derived from the first digital output. The first DAC feedback circuit transfers a first truncation residue associated with the first noise-shaped truncation output to the internal DAC. The transferred first truncation residue is reflected in comparison of a later-sampled analog input of the multi-bit ADC via the internal DAC.

Systems and methods for a power-efficient 3-level digital-to-analog converter. A converter cell using a current starving technique keeps a portion of the converter cell turned on in a low power mode, as opposed to completely turning off current in selected modes. A conversion system keeps a first set of converters active while allowing a second set of converters to be powered down. Systems and methods presented save power and allow for efficient reactivation of converters.

An analog-to-digital converter (“ADC”) includes an input terminal configured to receive an analog input signal. A first ADC circuit is coupled to the input terminal and includes a VCO. The first ADC circuit is configured to output a first digital signal in a frequency domain based on the analog input signal. The first digital signal includes an error component. A first DAC is configured to convert the first digital signal to an analog output signal. A first summation circuit is configured to receive the analog output signal, the analog input signal, and a loop filtered version of the analog input signal and extract the error component, and output a negative of the error component. A second ADC circuit is configured to convert the negative of the error component to a digital error signal. A second summation circuit is configured to receive the first digital signal and the digital error signal, and to output a digital output signal corresponding to the analog input at an output terminal.

A voltage-controlled oscillator-based delta-sigma analog-to-digital converter (VCO-based ΔΣ ADC) includes a VCO-based quantizer that includes delay elements to provide VCO outputs based on an analog input signal and combining logic to combine the VCO outputs so as to provide quantized outputs. Detection logic detects saturation of the VCO-based quantizer based on the quantized outputs and at least a portion of the VCO outputs. The VCO-based ΔΣ ADC also includes correction logic to modify the quantized outputs and provide modified quantized outputs in response to the detection logic detecting the saturation of the VCO-based quantizer and to provide the quantized outputs unmodified in the absence of saturation being detected.

Systems and methods for improving noise efficiency in a Delta Sigma modulator. A bypass scheme for a noise splitter is disclosed that reduces toggling activity for small signals. In particular, a sample-by-sample bypass noise splitter is disclosed that includes a noise splitting module and a bypass line. The bypass line bypasses the noise splitting module when signals are below a selected threshold, increasing efficiency of the system.

The number of bits in the quantizer can be decoupled from the number of bits in the feedback digital-to-analog converter (DAC) A delta-sigma analog-to-digital converter circuit can include a first quantizer to generate an output having a first number of bits and a second quantizer coupled to an output of the first quantizer, where the second quantizer can receive the output of the first quantizer and generate an output having a second number of bits. The feedback DAC can be coupled to the second quantizer to receive a representation of the output of the second quantizer, where the output of the feedback digital-to-analog converter circuit has the second number of bits. These techniques can reduce the area of the feedback DAC, e.g., 4 or 5 bits, and the techniques can achieve a higher maximum stable amplitude (MSA) because it is effectively a second order loop.

Systems and methods are provided for architectures for a digital class D driver that increase the power efficiency of the class D driver. In particular, systems and methods are provided for a digital class D driver having a feedback analog-to-digital converter (ADC) that can have a latency of 1 cycle or more than 1 cycle. A feedback ADC with a latency of 1 cycle or more is significantly lower power than a low latency feedback ADC. Systems and methods are disclosed for a power efficient digital class D driver architecture that allows for a latency of one or more cycles in the feedback ADC.

A delta-sigma modulator includes a first amplifier having an input, a feedback control input, and an output. The input is a first input of the delta-sigma modulator. The delta-sigma modulator further includes a first integrator and a first quantizer. The first integrator has an input and an output. The output of the first amplifier is coupled to the input of the first integrator. The first quantizer has an input and an output. The output of the first quantizer is coupled to the feedback control input of the first amplifier.