An apparatus is disclosed for pipelined analog-to-digital conversion. In an example aspect, the apparatus includes a pipelined analog-to-digital converter (ADC). The pipelined ADC includes a first stage and a second stage. The first stage includes a sampler and a quantizer coupled to the sampler. The first stage also includes a current distribution circuit coupled to the sampler. The second stage includes a sampler coupled to the current distribution circuit and a quantizer coupled to the sampler of the second stage.

Noise sources in a pipelined ADC circuit can include kT/C sampling noise from a capacitor DAC circuit and residue amplifier sampling noise. The kT/C sampling noise is inversely proportional to the size of the sampling capacitors; the larger sampling capacitors produce less noise. However, larger sampling capacitor can be difficult to drive and physically occupy significant die area. By using the described techniques, the inversely proportional relationship between the sampling noise and the size of the sampling capacitors is no longer true. The size of the sampling capacitors can be greats reduced, which can reduce the die area and reduce the power consumption of the ADC, and the kT/C sampling noise can be canceled using correlated double sampling (CDS) techniques.

An analog-to-digital converter includes: a voltage-current converter receiving an analog input voltage, generating a first digital signal from the analog input voltage, and outputting a residual current remaining after the first digital signal; a current-time converter converting the residual current into a current time in a time domain; and a time-digital converter receiving the residual time, and generating a second digital signal from the residual time, wherein the first digital signal and the second digital signal are sequences of digital codes representing respective signal levels of the analog input voltage.

The invention provides a signal processing system, for transferring analog signals from a probe to a remote processing unit. The system comprises a first ASIC at a probe, which is adapted to receive an analog probe signal. The first ASIC comprises an asynchronous sigma-delta modulator, wherein the asynchronous sigma-delta modulator is adapted to: receive the analog probe signal; and output a binary bit-stream. The system further comprises a second ASIC at the remote processing unit, adapted to receive the binary bit-stream. The asynchronous may further include a time gain function circuit, the first ASIC may further comprise a multiplexer, the second ASIC may further comprise a time-to-digital converter. The time to digital converter may be a pipelined time-to-digital converter.

Systems and methods relating to analog-to-digital converters. A delay block receives an input signal at the same time as a coarse ADC (CADC) block. The CADC block produces a multi-bit output and this output is applied to a signal processing block. The delay block delays the input signal from being applied to the signal processing block until the output of the CADC block has been applied/configures the signal processing block. The signal processing block may be a signal shifter, the output of which is ultimately applied to a fine ADC (FADC) block. In an alternative, the signal processing block may be the FADC block. Regardless of the configuration, the output of the CADC is delayed until the output of the FADC block is available. The outputs of the CADC and the FADC blocks are then simultaneously applied to an encoder that produces the overall system output.

A pipeline analog to digital converter includes converter circuitries and a calibration circuitry. The converter circuitries sequentially convert an input signal into a plurality of first digital codes, in which a first converter circuitry in the converter circuitries is configured to perform a quantization according to a first signal to generate a first corresponding digital code in the first digital codes, and the first signal is a signal, which is processed by the first converter circuitry, of the input signal and a previous stage residue signal. The calibration circuitry combines the first digital codes to output a second digital code, detects whether the quantization is completed to generate control signals, and determines whether to set the second digital code to be a second corresponding digital code in predetermined digital codes according to the control signals.

In one aspect, a transfer function (TF) estimation circuit configured to generate an estimate of a TF undergone by signals between an input of a digital-to-analog converter (DAC) of a feedforward path of a continuous-time (CT) stage of an analog-to-digital converter (ADC) and an output of a backend ADC of the ADC is disclosed. The TF estimation circuit includes one or more circuits configured to generate a first cross-correlation output by cross-correlating digital versions of signals based on a test signal provided to the CT stage and an output signal of the backend ADC, generate a second cross-correlation output by cross-correlating digital versions of signals based on the test signal and an output signal of a quantizer of the feedforward path of the CT stage, and generate the estimate of the TF based on the first and second cross-correlation outputs.

The exemplified disclosure presents a successive approximation register analog-to-digital converter circuit that comprises a two-step (e.g., two-stage) analog-to-digital converter (ADC) that operates a 1st-stage successive approximation register (SAR) in the continuous time (CT) domain (also referred to as a “1-st stage CTSAR”) that then feeds a sampling operation location in the second stage. Without a front-end sampling circuit in the 1st-stage, the exemplary successive approximation analog-to-digital converter circuit can avoid high sampling noise associated with such sampling operation and thus can be configured with a substantially smaller input capacitor size (e.g., at least 20 times smaller) as compared to conventional Nyquist ADC with a front-end sample-and-hold circuit.

A differential residue amplifier fits between Analog-to-Digital Converter (ADC) stages. Switched-Capacitor Common-Mode Feedback circuits determine voltage shifts. An AC-coupled input network uses switched capacitors to shift upward voltages of the differential inputs to the residue amplifier to apply to an upper pair of p-channel differential transistors with sources connected to the power supply. The AC-coupled input network also shifts downward in voltage the differential inputs to the residue amplifier to apply to a lower pair of n-channel differential transistors with grounded sources. The drains of the p-channel differential transistors connect to differential outputs through p-channel cascode transistors. N-channel cascode transistors connect the drains of the n-channel differential transistors to the differential outputs. The drains of differential transistors can be input to differential amplifiers to drive the gates of the cascode transistors for gain boosting. No tail current is used, allowing for wider output-voltage swings with low supply voltages.

There is described an analog-to-digital converter, ADC, device (100), comprising: i) a first converter stage (110), comprising a first digital-to-analog converter, DAC, (115), comprising at least two first unit elements (116, 117, 118) each with a first unit element value (U11, U12, U13); ii) a second converter stage (120), comprising a second DAC (125), comprising at least two second unit elements each with a second unit element value (U21, U22, U23); and iii) a control device (180), coupled to the first DAC (115) and the second DAC and configured to: swap at least one of the first unit element values (U1) with at least one of the second unit element values (U2) to obtain corresponding third unit element values (U3) and forth unit element values (U4).