A conversion and folding circuit includes a voltage-to-delay converter block, including preamplifiers, for converting a voltage signal into delay signals, and a folding block, including logic gates coupled to the preamplifiers, for selecting earlier-arriving and later-arriving ones of the delay signals. If desired, the logic gates may include odd and even chains for outputting delay signals to first and second analog-to-digital converters. If desired, the conversion and folding circuit may include first and second chains, and a chain selection circuit for selectively outputting a delay signal from a desired one of the first and second chains.

A system and method for sampling an RF signal uses a plurality of capacitors, a plurality of resistors, and a sampling circuit. A first port of each capacitor of the plurality of capacitors is coupled to the RF signal. A first port of each resistor of the plurality of resistors is coupled to one of a plurality of reference levels. A second port of each resistor of the plurality of resistors is coupled to a second port of a corresponding capacitor of the plurality of capacitors. The sampling circuit produces a plurality of digital outputs by sampling the second port of each resistor of the plurality of resistors.

A reference voltage sub-system that allows fast power up after spending extended periods in an ultra-low power standby mode. The reference voltage sub-system includes a reference voltage buffer, a reference voltage keeper, an active calibration facility for selectively adjusting the reference voltage keeper output to match the reference voltage buffer output, and a selection means for selecting between the reference voltage buffer output and the reference voltage keeper output.

A reference voltage sub-system that allows fast power up after spending extended periods in an ultra-low power standby mode. The reference voltage sub-system includes a reference voltage buffer, a reference voltage keeper, an active calibration facility for selectively adjusting the reference voltage keeper output to match the reference voltage buffer output, and a selection means for selecting between the reference voltage buffer output and the reference voltage keeper output.

A reference voltage sub-system that allows fast power up after spending extended periods in an ultra-low power standby mode. The reference voltage sub-system includes a reference voltage buffer, a reference voltage keeper, an active calibration facility for selectively adjusting the reference voltage keeper output to match the reference voltage buffer output, and a selection means for selecting between the reference voltage buffer output and the reference voltage keeper output.

In described examples, an analog to digital converter (ADC), having an input operable to receive an analog signal and an output operable to output a digital representation of the analog signal, includes a voltage to delay (VD) block. The VD block is coupled to the input of the ADC and generates a delay signal responsive to a calibration signal. A backend ADC is coupled to the VD block, and receives the delay signal. The backend ADC having multiple stages including a first stage. A calibration engine is coupled to the multiple stages and the VD block. The calibration engine measures an error count of the first stage and stores a delay value of the first stage for which the error count is minimum.

A system and method for sampling an RF signal are described. The system comprises a plurality of capacitors, a plurality of resistors, and a sampling circuit. A first port of each capacitor of the plurality of capacitors is coupled to the RF signal. A first port of each resistor of the plurality of resistors is coupled to one of a plurality of reference levels. A second port of each resistor of the plurality of resistors is coupled to a second port of a corresponding capacitor of the plurality of capacitors. The sampling circuit produces a plurality of digital outputs by sampling the second port of each resistor of the plurality of resistors.

A system and method for sampling an RF signal are described. The system comprises a plurality of capacitors, a plurality of resistors, and a sampling circuit. A first port of each capacitor of the plurality of capacitors is coupled to the RF signal. A first port of each resistor of the plurality of resistors is coupled to one of a plurality of reference levels. A second port of each resistor of the plurality of resistors is coupled to a second port of a corresponding capacitor of the plurality of capacitors. The sampling circuit produces a plurality of digital outputs by sampling the second port of each resistor of the plurality of resistors.

An analog-to-digital converter ADC may be provided. The ADC may include a current driving circuit. The current driving circuit may include an additive current driving circuit and a subtractive current driving circuit configured for adjusting a voltage level of a node. The ADC may include a comparison circuit including a plurality of comparators. Each of the plurality of comparators may be configured to compare a voltage level of the node with a reference voltage.

A reference voltage sub-system that allows fast power up after spending extended periods in an ultra-low power standby mode. The reference voltage sub-system includes a reference voltage buffer, a reference voltage keeper, an active calibration facility for selectively adjusting the reference voltage keeper output to match the reference voltage buffer output, and a selection means for selecting between the reference voltage buffer output and the reference voltage keeper output.