A Sub-electron-noise Skipper-CCD Readout ASIC with Improved Channel-to-channel Isolation and an Integrated Cryogenic Voltage Reference

TL;DR

This paper introduces an improved skipper-CCD readout ASIC capable of sub-electron noise performance at cryogenic temperatures, featuring enhanced channel isolation and an integrated voltage reference for better reliability and accuracy.

Contribution

The paper presents a new ASIC design with an on-chip voltage reference and improved channel isolation, enabling ultra-low noise CCD readout at cryogenic temperatures.

Findings

Achieved 0.11 e- RMS noise at 140 K with 1200 samples

Channel-to-channel crosstalk better than -62 dB

Demonstrated single-electron resolution in measurements

Abstract

The MIDNA application specific integrated circuits (ASICs) are a series of skipper-CCD readout chips fabricated in a 65 nm low-power CMOS process that implement a correlated double sampling signal processing chain based on dual-slope integrators. They are capable of working from room to cryogenic temperatures, down to 84 K. The present iteration of the ASIC has been fabricated including several design updates and the addition of an on-chip voltage reference, resulting in improved performance. This work presents the main vulnerabilities solved, the changes carried out, and the resulting performance benefits. Measurements with a skipper-CCD and the ASIC at 140 K showed that the single-electron resolution can be reached by averaging the measured charge in the analog domain using the analog pile-up technique with a readout noise as low as 0.11 erms of equivalent charge for 1200 samples. The channel-to-channel crosstalk was also characterized showing values better than -62 dB.