LAB4D: A low power, multi-GSa/s, transient digitizer with sampling timebase trimming capabilities

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 925; no. C; pp. 92 - 100
• Main Authors: Roberts, Jarred M., Varner, Gary S., Allison, Patrick, Fox, Brendan, Oberla, Eric, Rotter, Ben, Spack, Stefan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2019; Elsevier
• Subjects: Analog to digital converter (ADC); Application specific integrated circuit (ASIC); Electronic detector readout concepts; Front-end electronics for detector readout; Switched capacitor array (SCA); Front-end electronics for detector readout; Application specific integrated circuit (ASIC); Analog to digital converter (ADC); Electronic detector readout concepts; Switched capacitor array (SCA)
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2019.01.091

The LAB4D is a new application-specific integrated circuit (ASIC) of the Large Analog Bandwidth Recorder and Digitizer with Ordered Readout (LABRADOR) family, for use in direct wideband radio frequency digitization such as is used in ultrahigh energy neutrino and cosmic ray astrophysics. The LAB4D is a single channel switched-capacitor array (SCA) 12-bit sampler with integrated analog-to-digital converters (ADC), developed in the TSMC 0.25µm process. The LAB4D, operating at 3.2GSa∕s, contains 4096 total samples arranged in 32 windows, for a total record length of 1280ns. The 3dB bandwidth is approximately 1.3GHz, with a directly-coupled 50Ω input. This represents a factor of 16 increase in the sample depth and an increase in analog bandwidth in comparison to the previous generation (LAB3) digitizer. Individually addressable windows allow for sampling and digitization to occur simultaneously, leading to nearly dead time-free kHz readout rates. All biases and current references are generated via internal digital-to-analog converters (DACs), resulting in a digitizer that requires minimal support circuitry. In addition, the LAB4D contains sample cell timebase trimming capabilities, reducing the intrinsic sample-to-sample time variance to less than 5ps, an improvement of about 80%. This feature allows the LAB4D to be used in precision timing applications and reduces post-hoc calibration requirements.