Analog Devices,inc.

Analog Devices International Unlimited Company

Analog Devices Global

Qingdong Meng

Jialin Zhao

Yunzhi Dong

Martin McCormick

Jose Barreiro Silva

Wei Wang

Hajime Shibata

Richard E Schreier

Wenhua William Yang

Donald W Paterson

Libo Meng

Theophane Weber

Martin Steven McCORMICK

A lidar system can be used to measure a distance to one or more objects in a target region, such as by transmitting light towards the target and then receiving light reflected or scattered from the target. Received light can be stored as charge on storage elements such as capacitors, where received light can be stored on different storage elements depending on a time of arrival of the received light. A reduction in the number of storage elements can be achieved by providing one or more groups of storage elements, where each group of storage elements can correspond to a digit of a time of flight, where the time of flight can be round trip travel time of a light beam travelling from the lidar system to the target region and then back to the lidar system. Each group of storage elements can be arranged in a binary tree of a decimal tree configuration. Additionally, a time of activation of each of the storage elements can be increased with an increasing time of flight, such as to compensate for a decreased strength of the received light as the time of flight increases.

Systems and methods for measuring a time of flight in a lidar system

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

For analog-to-digital converters (ADCs) which utilize a feedback digital-to-analog converter (DAC) for conversion, the final analog output can be affected or distorted by errors of the feedback DAC. A digital measurement technique can be implemented to determine timing mismatch error for the feedback DAC in a continuous-time delta-sigma modulator (CTDSM) or in a continuous-time pipeline modulator. The methodology utilizes cross-correlation of each DAC unit elements (UEs) output to the entire modulator output to measure its timing mismatch error respectively. Specifically, the timing mismatch error is estimated using a ratio based on a peak value and a value for the next tap in the cross-correlation function. The obtained errors can be stored in a look-up table and fully corrected in digital domain or analog domain.

Digital measurement of DAC timing mismatch error

An approach to linearization relaxes the requirements on the digitization of the analog output signal while maintaining the benefits of a high sampling rate of the output signal. The digitization approach extracts sufficient information to characterize the output signal over a wide bandwidth without necessarily determining sufficient information to fully represent the output signal, for example, without sampling the output signal at the Nyquist sampling rate with a sufficient precision to accurately represent the signal.

Relaxed digitization system linearization

Growing community of inventors

Belmont, MA, United States of America

Qingdong Meng