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

Abstract

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 0.25 µm process.The LAB4D, operating at 3.2 GSa/s, contains 4096 total samples arranged in 32 windows, for a total record length of 1280 ns. The 3 dB bandwidth is approximately 1.3 GHz, with a directly-coupled 50 Ω 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 digi- * tizer that requires minimal support circuitry. In addition, the LAB4D contains sample cell timebase trimming capabilities, reducing the intrinsic sample-tosample time variance to less than 5 ps, an improvement of about 80%. This feature allows the LAB4D to be used in precision timing applications and reduces post-hoc calibration requirements.

Constraints on the diffuse flux of ultrahigh energy neutrinos from four years of Askaryan Radio Array data in two stations

“…The signal is stored in the circular buffer of an IceRay Sampler 2 chip, which is a high-speed 3.2 Gs=s digitizer application specific integrated circuit [33]. To minimize power consumption, the buffers are implemented in analog as switched capacitor arrays [34,35]. After a global trigger is issued, sampling is halted and analog-to-digital conversion commences.…”

Hardware Development for the Radio Neutrino Observatory in Greenland (RNO-G)

“…-In-house developed, 24 channel digitizer board that utilizes the LAB4D ASIC [6] -4-channel, low threshold trigger board with FPGA-based phased array trigger [7] -Controller board powered by a commercial single board computer -Low-noise amplifiers for receiver of surface antennas and RF-over-fiber receivers for deep antennas -GPS receiver for timing and position calibration -Calibration pulser source with transmitter to 'helper strings'…”

“…Due to the specific power constraints of RNO-G, digitization of antenna signals is performed on an in-house developed board, the RAdio DIgitizer and Auxiliary Neutrino Trigger (RADIANT) board. The RADIANT is a 24 channel board that uses the LAB4D, a custom ASIC that is a single channel, switched-capacitor array with 12-bit sampling [6]. For the purposes of RNO-G, the LAB4Ds are operated at 3.2 GSa/s with two buffers of 2048 samples each, giving a total 1280 ns recorded window per channel.…”

Coherent radar reflections from an electron-beam induced particle cascade

“…The experimental setup is shown in Figure 1. Two independent data acquisition systems (DAQ) were employed, one was a 4-channel Tektronix 20 GS/s oscilloscope, and the other was a new, custom 12-channel, 3.2 GS/s DAQ called the SURFv5, based on the LAB4D analog-to-digital converter chip [15]. These DAQ systems will be referred to as "scope" and "SURF", respectively.…”