Disclosed examples include pipeline ADC, balancing circuits and methods to balance a load of a reference circuit to reduce non-linearity and settling effects for a reference voltage signal, in which balancing capacitors are connected to a voltage source in a pipeline stage ADC sample time period to precharge the balancing capacitors using a voltage above the reference voltage, and a selected set of the precharged balancing capacitors is connected to provide charge to the output of the reference circuit during the second time period.

A converter may include multiple converter stages connected in series. Each converter stage may receive a clock signal and an analog input signal, and may generate an analog output signal and a digital output signal. Each converter stages may include an encoder generating the digital output signal, a decoder generating a reconstructed signal, a delaying converter generating a delayed signal, and an amplifier generating a residue signal, wherein the delayed signal may be a continuous current signal.

VCO ADCs consume relatively little power and require less area than other ADC architectures. However, when a VCO ADC is implemented by itself, the VCO ADC can have limited bandwidth and performance. To address these issues, the VCO ADC is implemented as a back end stage in a VCO-based continuous-time (CT) pipelined ADC, where the VCO-based CT pipelined ADC has a CT residue generation front end. Optionally, the VCO ADC back end has phase interpolation to improve its bandwidth. The pipelined architecture dramatically improves the performance of the VCO ADC back end, and the overall VCO-based CT pipelined ADC is simpler than a traditional continuous-time pipelined ADC.

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.

Systems and methods are provided for a pipelined analog-to-digital converter (ADC) circuit. The pipelined ADC circuit comprises a plurality of stages. Each stage comprises a differential input configured to receive a differential signal, a multiplying digital-to-analog converter (MDAC) electrically coupled to the input configured to stack voltages of a set of capacitors; a comparator electrically disposed after the MDAC to compare the differential voltages; and a source follower buffer electrically coupled to the first signal line and the second signal line and electrically disposed after the comparator, wherein the MDAC is configured to amplify an output voltage using passive multiplication; and an alignment circuit communicatively connected to a digital bit output of each stage of the plurality of stages, wherein the alignment circuit is configured to delay a digital bit output of each stage for one or more clock cycles and output a digitized representation of a sampled differential signal.

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.

A multi-stage pipelined Analog-to-Digital Converter (ADC) has an offset correction circuit embedded in the residue amplifier between stages. The offset corrector has a low-pass filter that filters the output of the residue amplifier, and the filtered offset is amplified and stored on an offset capacitor during an autozeroing phase of the residue amplifier. During an amplify phase of the residue amplifier, switches disconnect the amplifier from the offset capacitor and instead ground the input of the offset capacitor, and other switches connect the output terminal of the offset capacitor to the input of the residue amplifier. The offset stored on the offset capacitor is combined with the residue voltage from the first ADC stage's capacitor array and applied to an input of the residue amplifier to effectively subtract the detected offset. Two offset capacitors and sets of switches can be used to implement a differential offset corrector.

An example apparatus includes: an analog input; a resistor circuit including a first reference output and a second reference output; a first amplifier including a first analog input, a first reference input, and a first amplifier output, the first analog input coupled to the analog input, the first reference input coupled to the first reference output; a second amplifier including a second analog input, a second reference input, and a second amplifier output, the second analog input coupled to the analog input, the second reference input coupled to the second reference output; a first comparator including a first comparator input, the first comparator input coupled to the first amplifier output; and a second comparator including a second comparator input, the second comparator input coupled to the second amplifier output; a first multiplexer including a first multiplexer input and a first residue output, the first multiplexer input coupled to the first amplifier output; and a second multiplexer including a second multiplexer input and a second residue output, the second multiplexer input coupled to the second amplifier output.

Herein disclosed are multiple embodiments of a signal-processing circuit that may be utilized in various circuits, including conversion circuitry. The signal-processing circuit may receive an input and produce charges on multiple different capacitors during different phases of operation based on the input. The charges stored on two or more of the multiple different capacitors may be utilized for producing an output of the signal-processing circuit, such as by combing the charges stored on two or more of the multiple different capacitors. Utilizing the charges on the multiple different capacitors may provide for a high level of accuracy and robustness to variations of environmental factors, and/or a low noise level and power consumption when producing the output.

A multiple-input analog-to-digital converter device includes analog-to-digital converter circuits arranged between input nodes and output nodes. The analog-to-digital converter circuits operate over respective conversion times to provide simultaneous conversion of the analog input signals into respective conversion time signals. A time-to-digital converter circuit includes timer circuitry common to the plurality of analog-to-digital converter circuits. The timer circuitry cooperates with the analog-to-digital converter circuits to convert the conversion time signals into digital output signals at the output nodes.