Xilinx, Inc.

Bob W Verbruggen

Christophe Erdmann

Bruno Miguel Vaz

Brendan Farley

John E McGrath

Roberto Pelliconi

Ali Boumaalif

Conrado K Mesadri

Ionut C Cical

Roswald Francis

Augusto R Ximenes

Pedro Faria

Ryan Kinnerk

An analog-to-digital converter (ADC) circuitry includes channels that are interleaved with each other to generate output digital signals from input analog signals. A first channel includes sub-ADC circuitry, amplitude detection circuitry, and correction circuitry. Random chopping is applied by chopping circuitry at the input of the sub-ADC circuitry while sampling. The sub-ADC circuitry outputs digital data corresponding to the chopping states. Gain mismatch within the chopping circuitry is mitigated by determining correction values via the amplitude detection circuitry and the correction circuitry and applying the correction values to the output of the sub-ADC circuitry. The amplitude detection circuitry determines an amplitude difference between data signals. The correction circuitry is coupled to the output of the amplitude detection circuitry. The correction circuitry generates the correction values based on the amplitude difference, and outputs the correction values to adjust the data signals.

Mitigating gain mismatch interference in analog-to-digital converter circuitry

Methods and apparatus for calibrating a gain for a circuit block are disclosed. An example method includes receiving a plurality of quantizer offsets, where the plurality of quantizer offsets represent calibration data for a quantizer configured to quantize an output of the circuit block, determining one or more differences based on one or more first quantizer offsets of the plurality of quantizer offsets and on one or more second quantizer offsets of the plurality of quantizer offsets, and determining an incremental change in a gain associated with the circuit block based on the one or more differences.

Gain calibration with quantizer offset settings

Methods and apparatus for time-to-digital conversion. An example apparatus includes a first input; a second input; a delay line coupled to the first input and comprising a plurality of first delay elements coupled in series, each of the plurality of first delay elements having a first delay time; a second delay element having an input coupled to the second input and having the first delay time; a third delay element having an input coupled to the second input and having a second delay time, the second delay time being smaller than the first delay time; a first set of arbiters having first inputs coupled to the delay line and having second inputs coupled to an output of the second delay element; and a second set of arbiters having first inputs coupled to the delay line and having second inputs coupled to an output of the third delay element.

Low-latency time-to-digital converter with reduced quantization step

A biasing scheme for a voltage-to-time converter (VTC). An example biasing circuit generally includes a reference current source; a feedback loop current source; an amplifier having a first input coupled to a target voltage node, having a second input, and having an output coupled to a control input of the reference current source and to a control input of the feedback loop current source; a first capacitive element; a first switch coupled in parallel with the first capacitive element; a second switch coupled between the feedback loop current source and the first capacitive element; and a third switch coupled between the first capacitive element and the second input of the amplifier.

Delay-tracking biasing for voltage-to-time conversion

A low current line termination circuit includes first and second input interfaces each configured to receive a Vreceive+ and a Vreceive&#x2212; voltage, respectively. The circuit further includes a first diode connected transistor ('DCT') coupled to the second input interface, a first switching transistor ('ST') coupled to the first DCT and to the first input interface, and a first delay element coupled between one of the input interfaces and a gate of the first ST. The circuit further includes a second DCT coupled to the one of the two input interfaces, a second ST coupled to the second DCT and to the second input interface, and a second delay element coupled between another of the two input interfaces and a gate of the second ST.

Low current line termination structure

A radar system includes a transmitter to transmit a sequence of pulses, a receiver to receive reflections of the transmitted pulses, and velocity detection circuitry to determine a velocity of an object in a path of the transmitted pulses based at least in part on the transmitted pulses and the reflected pulses. The transmitter includes a plurality of digital-to-analog converters (DACs) to generate the sequence of pulses in response to a clock signal. The receiver includes a plurality of analog-to-digital converters (ADCs) to sample the reflected pulses in response to the clock signal. Accordingly, the ADCs are locked in phase with the DACs.

Phase noise compensation in digital beamforming radar systems

Methods and apparatus for tracking delay in signals sent from a first clock domain to a second clock domain are disclosed. For example, at a first time a common timing reference signal (SysRef) may be received at the first clock domain, and a latency marker may be input into a first-in first-out data structure (FIFO) coupling the first clock domain to the second clock domain. At a second time, the SysRef may be received at the second clock domain, and a timer may be started at the second clock domain. At a third time, the latency marker may be received from the FIFO at the second clock domain, and the counter may be stopped at a final count. A FIFO latency may be determined based on the final count and on a difference between the second time and the first time.

Latency synchronization across clock domains

An apparatus and method for sampling an analog signal with analog-to-digital converters (ADCs) is disclosed. The ADCs may be separated into a group of interleaved ADCs and a spare ADC. The interleaved ADCs can sample the analog signal according to an interleaving sequence. An interleaved ADC controller can monitor the inactivity of the spare ADC and can replace one of the interleaved ADCs in the interleaving sequence with the spare ADC based on the inactivity.

Method and apparatus for psuedo-random interleaved analog-to-digital converter use

A duty-cycle adjustment circuit receives a differential pair of input signals and generates an output signal based on the differential pair. The duty-cycle adjustment circuit drives the output signal to a logic-high state based on transitions of a first polarity in a first input signal of the differential pair, and drives the output signal to a logic-low state based on transitions of the first polarity in a second input signal of the differential pair. For example, rising-edge transitions of the output signal may be aligned with rising-edge transitions of the first input signal, and falling-edge transitions of the output signal may be aligned with rising-edge transitions of the second input signal. Alternatively, rising-edge transitions of the output signal may be aligned with falling-edge transitions of the first input signal, and falling-edge transitions of the output signal may be aligned with falling-edge transitions of the second input signal.

Duty-cycle correction using balanced clocks

Apparatus and associated methods relate to maintaining a total current of a switch cell in a digital-to-analog converter at a controllable operating point by adjusting shunt current control signals applied to programmable shunt current sources in opposite polarity with respect to a tail current control signal applied to a programmable tail current source. In an illustrative example, the total current may flow through differential legs of a switch cell. The programmable shunt current sources may, for example, be configured to compensate for adjustments to the programmable tail current source. In an illustrative example, tail current and shunt currents may flow through a pair of cascode transistors. In various examples, controlling the programmable shunt current sources to compensate adjustments to the tail current source may, for example, permit controlled common mode voltage or operating point so as to reduce device voltage stress over a wider dynamic range of output voltages.

Embedded variable output power (VOP) in a current steering digital-to-analog converter

Apparatus and associated methods relating to a digital-to-analog converter (DAC) include a programmable resistance network coupled between a voltage supply node Vand a switch cell circuit to provide a predetermined resistance in response to the Vand current Iof the switch cell circuit. In an illustrative example, the DAC may include a switch cell circuit comprising one or more switch cells connected in parallel. Each switch cell may include a differential gain circuit having a first branch coupled to a second branch at an input of a current source. The programmable resistance may include a variable resistance configured to adjust a voltage (Vbias) supplied to the switch cell circuit in response to a control signal. By introducing the programmable resistance network, predetermined bias and/or gain values may be dynamically adjusted with a constant board-level power supply V.

Embedded variable gain amplifier in a current steering digital-to-analog converter

Apparatus and associated methods relate to modulating polarity on sample outputs from a time-interleaved analog-to-digital converter (TIADC) as an input to a time skew extractor in a clock skew calibration control loop. In an illustrative example, a multiplier-mixer may impart a polarity change to every other data sample transmitted between the TIADC and the time skew extractor. In some examples, a multiplexer may select between the polarity modulated samples and non-polarity modulated samples before the multiplier-mixer. Selection between the polarity modulated samples and the non-polarity modulated samples may be based on, for example, determination of specific frequency bands of an analog input signal. Various embodiments may improve convergence of clock skew calibration control loops for analog input signals sampled with a TIADC near a Nyquist frequency.

Time skew calibration of time-interleaved analog to digital converters

A clock divider circuit receives an input clock signal having a first frequency (f) and generates an output signal having a frequency equal to f/N, where N is an odd integer. The clock divider circuit includes an edge counter to count a number of consecutive edges of the input clock signal having a first plurality, and to assert a control signal when a threshold number (N) of consecutive edges has been counted. The clock divider circuit also includes a frequency multiplier to generate an intermediate clock signal having a frequency equal to 2f/N by doubling the frequency of the control signal based at least in part on transitions of the input clock signal, and a frequency divider to generate an output clock signal having a frequency equal to f/N by halving the frequency of the intermediate clock signal.

Clock divide-by-three circuit

An example digital-to-time converter (DTC) includes: a delay chain circuit having a plurality of delay cells coupled in sequence, the delay chain circuit including a first input to receive a first clock signal and a second input to receive a second clock signal; and a DEM controller coupled to the delay chain circuit to provide a plurality of control signals to the plurality of delay cells, respectively.

Dual-path digital-to-time converter

An example apparatus for analog-to-digital conversion includes a plurality of channels each including an analog-to-digital converter (ADC), a switch configured to couple a differential input to the ADC, a first offset calibration circuit coupled to an output of the ADC, a multiplier coupled to an output of the first offset calibration circuit, a second offset calibration circuit coupled to an output of the multiplier, and a pseudorandom bit sequence (PRBS) generator coupled to the switch and the multiplier. The apparatus further includes a gain calibration circuit coupled to an output of the second offset calibration circuit in each of the plurality of channels; and a time-skew calibration circuit coupled to an output of the gain calibration circuit.

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Saggart, Ireland

Bob W Verbruggen