Abstract:
A CMOS analog and audio front-end circuit includes an enhanced analog-to-digital converter (ADC) that achieves a desired signal-to-noise-and-distortion (SNDR) and an analog-front-end transmit (TX) digital-to-analog converter (DAC). The enhanced ADC includes an improved single Op-Amp resonator coupled to a feed-forward loop and can substantially reduce signal transfer function (STF) peaking of the enhanced ADC. The CMOS analog and audio front-end circuit is integrated with a baseband processor.
Abstract:
An analog-to-digital converter (ADC) includes reference charge cancellation features to at least partially offset a voltage distortion on a bypass capacitor of a reference buffer due to a voltage reference hit taken by a switched capacitor bank with which the bypass capacitor is connected. The charge cancellation may be configured in logic to be input signal dependent because different resolved bits or transitions between resolved bits may cause different amounts of voltage reference hits. By adjusting the bypass capacitor in response to each of at least some of the reference hits while resolving a word of bits, the reference voltage signal provided by the bypass capacitor undergoes far less settling, remaining more stable and linear for a more accurate reference voltage. Furthermore, a smaller capacitor may be used for the bypass capacitor, reducing power consumption and area on chip.
Abstract:
A CT-SDADC of the present disclosure converts the analog input signal from a representation in an analog signal domain to a representation in a digital signal domain to provide the digital output signal. The CT-SDADC achieves the analog-to-digital conversion and ELDC by switching between two phases in the SAR sub-ADC: a sampling phase and a conversion phase. During the sampling phase, the SAR sub-ADC captures the analog input signal across multiple arrays of switchable capacitors. The conversion phase comprises a number of steps, and one or more bits of the digital output signal are resolved at each step of the conversion phase. A portion of the SC-DAC is driven by the delayed CT-SDADC output during the conversion phase to effectively compensate for excess loop delay caused by the CT-SDADC feedback loop.
Abstract:
A CT-SDADC of the present disclosure converts the analog input signal from a representation in an analog signal domain to a representation in a digital signal domain to provide the digital output signal. The CT-SDADC achieves the analog-to-digital conversion and ELDC by switching between two phases in the SAR sub-ADC: a sampling phase and a conversion phase. During the sampling phase, the SAR sub-ADC captures the analog input signal across multiple arrays of switchable capacitors. The conversion phase comprises a number of steps, and one or more bits of the digital output signal are resolved at each step of the conversion phase. A portion of the SC-DAC is driven by the delayed CT-SDADC output during the conversion phase to effectively compensate for excess loop delay caused by the CT-SDADC feedback loop.
Abstract:
An analog-to-digital converter (ADC) includes reference charge cancellation features to at least partially offset a voltage distortion on a bypass capacitor of a reference buffer due to a voltage reference hit taken by a switched capacitor bank with which the bypass capacitor is connected. The charge cancellation may be configured in logic to be input signal dependent because different resolved bits or transitions between resolved bits may cause different amounts of voltage reference hits. By adjusting the bypass capacitor in response to each of at least some of the reference hits while resolving a word of bits, the reference voltage signal provided by the bypass capacitor undergoes far less settling, remaining more stable and linear for a more accurate reference voltage. Furthermore, a smaller capacitor may be used for the bypass capacitor, reducing power consumption and area on chip.