Analog Devices Global

Analog Devices,inc.

Analog Devices Technology

Analog Devices International Unlimited Company

Analog Devices Global Unlimited Company

Richard E Schreier

Hajime Shibata

Wenhua William Yang

Trevor Clifford Caldwell

Yunzhi Dong

David Nelson Alldred

Jialin Zhao

Donald W Paterson

Zhao Li

Victor Kozlov

Prawal Man Shrestha

Jose Barreiro Silva

Jipeng Li

Kevin Cao-Van Lam

Khiem Quang Nguyen

David H Robertson

Iuri Mehr

Martin McCormick

Steven C Rose

Qingdong Meng

Hassan L'Bahy

Nazmy Abaskharoun

Andre Straker

Sergei Nesterenko

Alexander Newcombe

Ross Willett

Martin Steven McCORMICK

David Alldred

A flash analog-to-digital converter (ADC) includes comparators that convert an analog input signal to a digital output signal. Offsets of these comparators introduce noise and can hurt the performance of the ADC. Thus, these comparators are calibrated using calibration codes. Conventional calibration methods determine these calibration codes by removing the ADC from an input signal. Otherwise, it is difficult to distinguish the noise from the signal in the calibration measurement. In contrast, an embodiment can determine the calibration codes while the ADC converts the input signal to a digital signal. Such an embodiment can be achieved by a frequency-domain technique. In an embodiment employing a frequency-domain power meter, an input signal can be removed from the power measurement. This removal enables accurate measurement of in-band noise without having the measurement be corrupted by input signal power.

Frequency-domain ADC flash calibration

An analog-to-digital converter (ADC) is a device that can include a reference shuffler and a loop filter. An ADC can achieve better performance with incremental adjustment of a pointer of the reference shuffler, changing coefficients of the loop filter, and storing calibration codes of the ADC in a non-volatile memory. By incrementally adjusting a pointer of the reference shuffler, a calibration can be performed more efficiently than with a random adjustment of the pointer. By temporarily changing the loop filter coefficients, a greater amount of activity can be introduced into the loop filter. This activity can allow the calibration to proceed more efficiently. By storing the calibration codes in a non-volatile memory, a search space for calibration codes can be reduced. Thus, a calibration can occur more quickly, and the calibration itself can be improved.

Flash analog-to-digital converter calibration

Analog-to-digital converters (ADCs) can be used inside ADC architectures, such as delta-sigma ADCs. The error in such internal ADCs can degrade performance. To calibrate the errors in an internal ADC, comparator offsets of the internal ADC can be estimated by computing a mean of each comparator of the internal ADC. Relative differences in the computed means serves as estimates for comparator offsets. If signal paths in the internal ADC are shuffled, the estimation of comparator offsets can be performed in the background without interrupting normal operation. Shuffling of signal paths may introduce systematic measurement errors, which can be measured and reversed to improve the estimation of comparator offsets.

Background flash offset calibration in continuous-time delta-sigma ADCS

For continuous-time multi-stage noise shaping analog-to-digital converters (CT MASH ADCs), quantization noise cancellation often requires accurate estimation of transfer functions, e.g., a noise transfer function of the front end modulator and a signal transfer function of the back end modulator. To provide quantization noise cancellation, digital quantization noise cancellation filters adaptively tracks transfer function variations due to integrator gain errors, flash-to-DAC timing errors, as well as the inter-stage gain and timing errors. Tracking the transfer functions is performed through the direct cross-correlation between the injected maximum length linear feedback shift registers (LFSR) sequence and modulator outputs and then corrects these non-ideal effects by accurately modeling the transfer functions with programmable finite impulse response (PFIR) filters.

Adaptive digital quantization noise cancellation filters for mash ADCs

Remote evaluation, e.g., web-based evaluation, lowers the evaluation barrier by allowing an engineer to gain experience with an integrated circuit (IC) using a client (e.g. a web browser) on a remote computer (e.g., a machine remote from the IC being evaluated but local to the engineer) to activate a test set-up that is maintained at a location that is far away from the engineer.

Remote evaluation tool

Data converters convert signals in analog form to digital form or from digital form to analog form. Due to mismatches between devices that are intended to be identical (unary elements), some data converters outputs may have undesirable characteristics, such as non-linearities. Shuffling the inputs to the unary elements based on a pseudo-random sequence is a technique that can average out the mismatches over time. However, shuffling generally requires a complex switch matrix, and can potentially impact the speed of the converter. To address mismatches, a high speed technique for rotating comparator thresholds is implemented to effectively rotate an array of unary digital-to-analog converter elements. The technique is particularly advantageous for addressing mismatches in unary digital-to-analog converters used for reconstructing a quantized analog signal within delta-sigma analog-to-digital converter.

Generating comparator thresholds using a rotating ring of resistors

A delta-sigma modulator is configured to sense and convert an electromagnetic field into a digital signal. An exemplary delta-sigma modulator includes a sensor component, such as an LC resonator, that is configured to sense the electromagnetic field and generate an input analog signal, where the delta-sigma modulator is configured to convert the input analog signal to the digital signal. Delta-sigma modulator can include an analog-to-digital converter coupled to the sensor component that receives and converts the input analog signal to the digital signal. Delta-sigma modulator can further include a digital-to-analog converter (DAC) coupled to the resonator and the ADC, the DAC configured to receive the digital signal from the ADC and generate a feedback analog signal.

Delta-sigma modulator having sensor front-end

In one aspect, an electrical signal converter is disclosed. The exemplary electrical signal converter may include a plurality of ordered converter elements. Element selection logic may be provided to pseudorandomly select a pointer to a switch matrix, wherein the switch matrix maps converter elements according to a stepwise 'delta-two-maximum pattern.' Advantageously, pseudorandom stepwise delta-two-maximum patterns may be applied both to a first order converter, and to a feedback converter for error correction.

Electrical signal conversion with reduced-distance element rotation

This disclosure describes techniques and methodologies of using passive continuous time (CT) delay line for high-speed CT analog-to-digital converter (ADC) applications. In a continuous-time residual producing stage common to these CT ADCs, a proper delay between the analog input and DAC output is crucial. Specifically, using an inductor-capacitor (LC) lattice based delay element to enable high-performance CT pipeline ADC and CT delta-sigma (&#x394;&#x3a3;) ADC. The use of an LC lattice based delay element provides wide-band group delay for continuous-time signals with well-controlled impedance. This will be an essential circuit component to build a high-performance CT ADCs especially in architectures where the generation of a low-noise and low-distortion residual between the CT signal and its digitized version is needed. LC lattice based delay element enables noise-free, distortion-free wideband delay that is required for high speed continuous-time pipeline ADC and delta-sigma ADC.

LC lattice delay line for high-speed ADC applications

A voltage generator may include a plurality of charge pumps, plural sets of delay pipelines and a phase controller. Given M delay pipelines having N stages each, there may be M*N charge pumps each having a triggering input coupled to a respective stage or a respective pipeline. The phase controller may include a plurality of phase control stages interconnecting among the delay pipelines to induce timing offsets among the outputs of the delay stage. In an alternate design, intermediate nodes among the pipeline's delay stages may be coupled to triggering inputs of a sub-set of the charge pumps. The phase controller may have a plurality of phase control stages coupled, respectively, between the intermediate nodes of the delay pipeline and intermediate nodes of the phase control stages may be coupled to triggering inputs of another sub-set of the charge pumps.

Charge pump supply with clock phase interpolation

An integrated circuit includes a component calculator configured to compute at least one component value of a highly programmable analog-to-digital converter (ADC) from at least one application parameter, and a mapping module configured to map the component value to a corresponding register setting of the ADC based on at least one process parameter, wherein the integrated circuit produces digital control signals capable of programming the ADC. In a specific embodiment, the component calculator uses an algebraic function of a normalized representation of the application parameter to approximately evaluate at least one normalized ADC coefficient. The component value is further calculated by decimalizing the normalized ADC coefficient. In another specific embodiment, the component calculator uses an algebraic function of the application parameter to calculate the component value. In some embodiments, the integrated circuit further includes a scaling module configured to scale the component value based on scaling parameters.

Digital tuning engine for highly programmable delta-sigma analog-to-digital converters

Digital-to-analog converters (DACs) are used widely in electronics. The DACs are usually not ideal and typically exhibits errors, e.g., static mismatch errors. This disclosure describes a digital calibration technique for DAC static mismatch in continuous-time delta-sigma modulators (CTDSMs). The methodology utilizes the DAC unit elements (UEs) themselves to measure each other's mismatch. There are no extra circuitries except for the logic design inside DAC drivers or comparators. The methodology is an attractive calibration technique for high performance CTDSMs, especially for high speed system in multi-gigahertz range with low over-sampling rate (OSR).

Estimation of digital-to-analog converter static mismatch errors

The present disclosure describes an improved multi-stage noise shaping (MASH) analog-to-digital converter (ADC) for converting an analog input signal to a digital output signal. In particular, a full delta-sigma (&#x394;&#x3a3;) modulator is provided at the front-end of the MASH ADC, and another full &#x394;&#x3a3; modulator is provided at the back-end of the MASH ADC. The front-end &#x394;&#x3a3; modulator digitizes an analog input signal, and the back-end &#x394;&#x3a3; modulator digitizes an error between the output of the front-end &#x394;&#x3a3; modulator and the (original) analog input signal. In this configuration where the back-end modulator digitizes the error of the (full) front-end modulator, some design constraints of the front-end are relaxed. These design constraints include thermal noise, digital noise cancellation filter complexity (the quantization noise of the front-end is already shaped by the noise transfer function of the front-end), and/or non-linearity.

Multi-stage noise shaping analog-to-digital converter

In one example implementation, the present disclosure provides a loop filter for use in a continuous-time sigma-delta analog-to-digital converter. Specifically, a capacitive feedback digital-to-analog converter path is provided at the input of a first opamp in a series of opamp integrators. The capacitive feedback digital-to-analog converter at the input of the first opamp reduces the signal content at the output of the first opamp, and thereby reduces the output swing of the first opamp. A reduction in output swing provides a more efficient loop filter.

Integrator output swing reduction

An integrated circuit includes a component calculator configured to compute at least one component value of a highly programmable analog-to-digital converter (ADC) from at least one application parameter, and a mapping module configured to map the component value to a corresponding register setting of the ADC based on at least one process parameter, wherein the integrated circuit produces digital control signals capable of programming the ADC. In a specific embodiment, the component calculator uses an algebraic function of a normalized representation of the application parameter to approximately evaluate at least one normalized ADC coefficient. The component value is further calculated by denormalizing the normalized ADC coefficient. In another specific embodiment, the component calculator uses an algebraic function of the application parameter to calculate the component value. In some embodiments, the integrated circuit further includes a scaling module configured to scale the component value based on scaling parameters.

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Toronto, Canada

Richard E Schreier