TAFA: Design Automation of Analog Mixed-Signal FIR Filters Using Time Approximation Architecture

TL;DR

This paper introduces a systematic, automated design methodology for analog mixed-signal FIR filters using a time approximation architecture, reducing manual effort and analog complexity while improving performance.

Contribution

It presents a novel automated design flow combining hybrid approximation and neural network-based layout modeling for AMS FIR filters without tunable passives.

Findings

Automated synthesis of AMS FIR filters from specification to layout in 65nm process.

Significant performance improvements with minimal designer intervention.

Reduction in analog complexity through time approximation architecture.

Abstract

A digital finite impulse response (FIR) filter design is fully synthesizable, thanks to the mature CAD support of digital circuitry. On the contrary, analog mixed-signal (AMS) filter design is mostly a manual process, including architecture selection, schematic design, and layout. This work presents a systematic design methodology to automate AMS FIR filter design using a time approximation architecture without any tunable passive component, such as switched capacitor or resistor. It not only enhances the flexibility of the filter but also facilitates design automation with reduced analog complexity. The proposed design flow features a hybrid approximation scheme that automatically optimize the filter's impulse response in light of time quantization effects, which shows significant performance improvement with minimum designer's efforts in the loop. Additionally, a layout-aware regression model based on an artificial neural network (ANN), in combination with gradient-based search algorithm, is used to automate and expedite the filter design. With the proposed framework, we demonstrate rapid synthesis of AMS FIR filters in 65nm process from specification to layout.