An analog to digital converter (ADC) senses an analog signal (e.g., a load current) to generate a digital signal. The ADC operates based on a load voltage produced based on charging of an element (e.g., a capacitor) by a load current and a digital to analog converter (DAC) output current (e.g., from a N-bit DAC). The ADC generates a digital output signal representative of a difference between the load voltage and a reference voltage. This digital output signal is used directly, or after digital signal processing, to operate an N-bit DAC to generate a DAC output current that tracks the load current. The digital output signal provided to the N-bit DAC is an inverse function of the load current. The ADC is operative to sense very low currents (e.g., currents as low as 1 s of pico-amps) and consume very little power (e.g., less than 2 .Math.W).

A successive approximation register analog-to-digital converter (SAR ADC) is disclosed, which is configured to receive an analog input signal and provide a digital output signal. The SAR ADC comprises a capacitor bank for successively providing a plurality of signal levels based on a sample value of the analog input signal, wherein each signal level of the plurality is an indicator for a corresponding bit in a corresponding sample of the digital output signal. Furthermore, the SAR ADC comprises controlling circuitry configured to cause the capacitor bank to provide the plurality of signal levels representing a dynamically scaled version of the sample value of the analog input signal. In some embodiments, a respective selector of each capacitor of the capacitor bank is controlled to charge the capacitor using either the sample value of the analog input signal or the sample value of an opposed version of the analog input signal. The setting of the respective selectors corresponds to a digital representation of a scaling value (e.g., a sample value of an oscillator signal) for the dynamically scaled version of the sample value of the analog input signal. Corresponding method, receiver, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG).

An analog-to-digital converter (“ADC”) includes an input terminal configured to receive an analog input voltage signal. A first ADC stage is coupled to the input terminal and is configured to output a first digital value corresponding to the analog input voltage signal and a first analog residue signal corresponding to a difference between the first digital value and the analog input signal. An inverter based residue amplifier is configured to receive the first analog residue signal, amplify the first analog residue signal, and output an amplified residue signal. The amplified residue signal is converted to a second digital value, and the first and second digital values are combined to create a digital output signal corresponding to the analog input voltage signal.

Circuitry and techniques are described herein for performing accurate and low power conversion of an analog value into a digital value. According to some aspects, this disclosure describes a successive approximation register (SAR) analog to digital converter (ADC). According to some aspects the SAR ADC comprises an active integrator between a sample and hold stage and a comparator stage. The active integrator operates differently dependent on whether the SAR ADC is operated in a sample phase or a conversion phase. According to other aspects, the SAR ADC utilizes a ring oscillator-based comparator to compare a sampled analog input value to a plurality of reference values to determine a digital value representing the analog value.

A method of operating an analog-to-digital converter includes in a first sampling stage, switching a swap signal to a first level for a first selection circuit to reset a first capacitor array according to a first voltage configuration and for a second selection circuit to reset a second capacitor array according to the first voltage configuration, and in a second sampling stage, switching the swap signal to a second level for the first selection circuit to reset the first capacitor array according to the second voltage configuration and for the second selection circuit to reset the second capacitor array according to the second voltage configuration. A control logic circuit is used to switch the swap signal between the first level and the second level in a uniform order in a plurality of sampling stages.

A differential subrange analog-to-digital converter (ADC) converts differential analog image signals received from sample and hold circuits to a digital signal through an ADC comparator. The comparator of the differential subrange ADC is shared by a successive approximation register (SAR) ADC coupled to provide both M upper output bits (UOB) and a ramp ADC coupled to provide N lower output bits (LOB). Digital-to-analog converters (DACs) of the differential subrange SAR ADC comprises 2M buffered bit capacitor fingers connected to the comparator. Each buffered bit capacitor finger comprises a bit capacitor, a bit buffer, and a bit switch controlled by the UOB. Both DACs are initialized to preset values and finalized based on the values of the least significant bit of the UOB. The subsequent ramp ADC operation will be ensured to have its first ramp signal ramps in a monotonic direction and its second ramp signal ramp in an opposite direction.

Aspects of a method and system for a successive approximation analog-to-digital converter with dynamic search algorithms are provided. In some embodiments, a successive approximation analog-to-digital converter includes a digital-to-analog converter, a comparator, and a search and decode logic modules which cooperate to generate a digital output code representative of the analog input voltage based on a dynamic search algorithm. The dynamic search algorithms may alter a sequence of reference voltages used to successively approximate the analog input voltage based on one or more characteristics of the analog input voltage.

In an example embodiment, an apparatus includes: a first sampling capacitor to switchably couple between an input analog voltage, a reference voltage (V.sub.REF) and a ground voltage; a second sampling capacitor to switchably couple between the reference voltage and the ground voltage; and a comparator having a first input terminal to couple to the first sampling capacitor and a second input terminal to couple to the second sampling capacitor. The comparator may be configured to compare a voltage level at the second input terminal to a sum voltage based at least in part on the input analog voltage to generate at least one bit of a digital output.

An analog to digital converter (ADC) senses an analog signal (e.g., a load current) to generate a digital signal. The ADC operates based on a load voltage produced based on charging of an element (e.g., a capacitor) by a load current and a digital to analog converter (DAC) output current (e.g., from a N-bit DAC). The ADC generates a digital output signal representative of a difference between the load voltage and a reference voltage. This digital output signal is used directly, or after digital signal processing, to operate an N-bit DAC to generate a DAC output current that tracks the load current. The digital output signal provided to the N-bit DAC is an inverse function of the load current. The ADC is operative to sense very low currents (e.g., currents as low as is of pico-amps) and consume very little power (e.g., less than 2 μW).

Aspects of the disclosure relate to an apparatus for wireless communication. The apparatus may include a set of power detectors configured to generate a set of analog signals related to a set of output signal power levels of a set of transmit chains of a transmitter, respectively; an analog summer; a set of switching devices configured to send a selected one or more of the set of analog signals to the analog summer, and substantially isolated unselected one or more of the set of power detectors from the analog summer, wherein the analog summer is configured to generate a cumulative analog signal based on a sum of the selected one or more of the set of analog signals; an analog-to-digital converter (ADC) configured to generate a digital signal based on the cumulative analog signal; and a controller configured to control the set of switching devices.