# Measured Effectiveness of Deep N-well Substrate Isolation in a 65nm Pixel Readout Chip Prototype

## TL;DR

This paper evaluates different substrate isolation strategies in a 65nm CMOS pixel readout chip, demonstrating that combining analog on substrate and digital in deep N-well improves noise isolation.

## Contribution

It provides experimental comparison of substrate isolation techniques, highlighting the effectiveness of deep N-well isolation for mixed-signal circuits.

## Key findings

- Analog on substrate and digital in deep N-well yields better noise isolation.
- Experimental results compare isolation effectiveness of different strategies.
- Study focuses on a 65nm CMOS process with charge sensitive preamplifier and discriminator.

## Abstract

The same charge sensitive preamplifier and discriminator circuit with different isolation strategies has been tested to compare the isolation of both analog and digital circuits from the substrate of a 65nm bulk CMOS process to the isolation of only digital circuits, tying analog ground locally to the substrate. This study will show that the circuit with analog on the substrate and digital in deep N-well has better noise isolation between analog and digital.