Abstract: An integrator stage for use in a delta sigma modulator includes an operational amplifier, an integration capacitor coupling an output of the operational amplifier and a summing node at an input of the operational amplifier, and a feedback path. The feedback path includes first and second capacitors having first plates coupled electrically in common at a common plate node and switching circuitry for sampling selected reference voltages onto second plates of the capacitors during a sampling phase. The integrator stage further includes a switch for selectively coupling the common plate node and the summing node during an integration phase.

Abstract: A noise shaper including first and second quantizers and first and second feedback paths each providing feedback from a corresponding quantizer output. A loop filter system implements a plurality of transfer functions including a first non-zero transfer function between the first feedback path and an input of the first quantizer, a second non-zero transfer function between the first feedback path and an input of the second quantizer, a third non-zero transfer function between the second feedback path and the input of the first quantizer and a fourth non-zero transfer between the second feedback path and the input the second quantizer.

Abstract: A system 100 including a radio receiver 101/108 and switched mode circuitry 114/115 operating at a selected switching frequency is disclosed. Circuitry 207-209 sets the switching-circuitry of the switched mode circuitry 114/115 as a function of a frequency of a signal being received by a radio receiver 101/108.

Abstract: A delta-sigma modulator for driving an output stage is disclosed. The delta-sigma modulator operates between first and second voltages and includes a loop filter, a quantizer, and a feedback loop coupling an output of the quantizer and an input of the loop filter. The feedback loop includes compensation circuitry for compensating for variations in the first and second voltages in response to a measured average of the first and second voltages and a measured difference between the first and second voltages. Measuring circuitry measures the average and the difference of the first and second voltages.

Abstract: A noise shaper including a filter system for generating a first set of poles and zeros characterizing noise attenuation in a signal baseband of a noise transfer function and at least one additional set of at least one pole and one zero characterizing noise attenuation in at least one additional band outside the baseband of the noise transfer function.

Abstract: A digital to analog converter including a noise shaping modulator for modulating an input digital data stream, a plurality of output elements for generating a plurality of intermediate data streams from a modulated output stream from the modulator, and an output summer for summing the intermediate data streams to generate an output analog stream. The noise shaping modulator balances an edge transition rate of the output elements, such that the edge transition rate of two selected elements is approximately equal.

Abstract: A noise shaper includes a first feedback loop for noise shaping a first feedback signal under normal operating conditions and having a first filter with a first signal transfer function and a second feedback loop that is stable under overload conditions and has a second filter having a second signal transfer function differing from the first signal transfer function. The noise shaper also includes an output circuit block including a quantizer and steering circuitry. The quantizer includes an input simultaneously responsive to outputs of the first and second filters. The steering circuitry steers a feedback from an output of the quantizer to input of the first and second feedback loops. The steering circuitry steers feedback from output of the quantizer to inputs of the first and second feedback loops, the steering circuitry including a first output for providing the first feedback signal to the first feedback loop and a second output for providing a second feedback signal to the second feedback loop.

Abstract: A noise shaper including first and second quantizers and first and second feedback paths each providing feedback from a corresponding quantizer output. A loop filter system implements a plurality of transfer functions including a first non-zero transfer function between the first feedback path and an input of the first quantizer, a second non-zero transfer function between the first feedback path and an input of the second quantizer, a third non-zero transfer function between the second feedback path and the input of the first quantizer and a fourth non-zero transfer between the second feedback path and the input the second quantizer.

Abstract: A noise shaper including a filter system for generating a first set of poles and zeros characterizing noise attenuation in a signal baseband of a noise transfer function and at least one additional set of at least one pole and one zero characterizing noise attenuation in at least one additional band outside the baseband of the noise transfer function.

Abstract: An integrator stage for use in a delta sigma modulator includes an operational amplifier, an integration capacitor coupling an output of the operational amplifier and a summing node at an input of the operational amplifier, and a feedback path. The feedback path includes first and second capacitors having first plates coupled electrically in common at a common plate node and switching circuitry for sampling selected reference voltages onto second plates of the capacitors during a sampling phase. The integrator stage further includes a switch for selectively coupling the common plate node and the summing node during an integration phase.

Abstract: An integrator stage for use in a delta sigma modulator includes an operational amplifier, an integration capacitor coupling an output of the operational amplifier and a summing node at an input of the operational amplifier, and a feedback path. The feedback path includes first and second capacitors having first plates coupled electrically in common at a common plate node and switching circuitry for sampling selected reference voltages onto second plates of the capacitors during a sampling phase. The integrator stage further includes a switch for selectively coupling the common plate node and the summing node during an integration phase.

Abstract: A delta-sigma data converter includes a first quantizer responsive to outputs of first and second loop filters, the first quantizer introducing a quantization error during quantization. The first loop filter is responsive to an output of the first quantizer. A second quantizer quantizes an error data stream representing the quantization error introduced by the first quantizer. The second loop filter includes an integrator for integrating a quantized error data stream output from the second quantizer. An analog output path responsive to the output of the first quantizer and an output of the integrator generates the converter output.

Abstract: A switched capacitor circuit 300, including a sampling capacitor 303, switches 301, 304 for charging the sampling capacitor 303 during a charging phase, and switches 302, 305 for transferring charge from the sampling capacitor 303 to a load 313 in the feedback loop of an operational amplifier 312 during a dump phase. Circuitry 701 controls the discharge of sampling capacitor 303 during the dump phase to minimize transients at the input of the operational amplifier 312 and thereby minimize input threshold voltage variation.

Abstract: A method of amplitude control in a 1-bit digital system includes the step of scaling the stream of 1-bit data by a scaling factor corresponding to a selected output amplitude. The scaled data is modulated and the resulting modulated, scaled data is converted from digital to analog form.

Abstract: An apparatus and method for limiting the output current in a switched mode amplifier are implemented. The apparatus includes a driver amplifier configurable for selective operation in one of three modes. The amplifier is operable for transitioning between the first mode and one of the second and third modes in response to a state of an output node of the driver. Bias circuitry, configurable for selective coupling to the driver amplifier is operable for limiting the output current of the amplifier in the first operating mode.

Abstract: A system and method for compensating switched mode amplifiers. The amplifier system includes an adaptive filter coupled to the output of circuitry that recovers the analog signal from the output of the switching amplifier circuitry. The adaptive filter derives an inverse transfer function of the forward path through the system. The derived inverse transfer function is used to generate a coefficient map which a compensation filter responsively compensates for from variations in the output load of the amplifier system. In the disclosed method, the deriving the inverse transfer function may further include calibrating the adaptive filter continuously, at system startup or in response to user demand.

Abstract: A delta-sigma modulator 400 includes circuitry 407 for selectively varying an order of the modulator to vary a modulation index of the delta sigma modulator.

Abstract: A system for suppressing transient noise in switched-mode amplifier systems is disclosed. An amplifier, for amplifying a signal from a digital signal source includes a first complementary metal oxide semiconductor field effect transistor (MOSFET) pair. A common node of the pair is serially coupled to an output node of the amplifier by a resistor. The first MOSFET pair is configured to drive a ramp on the output node of the amplifier.

Abstract: An output stage 300 includes a first output switch 201 having a current path for driving an output from a first voltage rail and a second output switch 202 having a current path for selectively driving the output from a second voltage rail. A first reference switch 301 is scaled with respects to first output switch 201 and has a current path coupled to the first voltage rail. A second reference switch 302 scaled with respects to second output switch 202 has a current path coupled to a current path of first reference switch 301 at a node and the second voltage rail. The logic measures an impedance mismatch between first and second reference switches 301, 302 and proportionally varies the impedance of a selected one of first and second output switches 201, 202 in response.

Abstract: An apparatus and method for power digital-to-analog converter protection are implemented. An attenuation value is set in response to the value of the supply voltage. The attenuation value is provided to a gain control, along with the input signal. A gain, offset by the attenuation value, determines the gain-adjusted output signal of the gain control generated from the input signal.