Classification of Sequential Circuits as Causal Functions

TL;DR

This paper introduces a new classification framework for sequential circuits based on the specific subset of past inputs they reference, unifying synchronous and multi-clock domain circuits.

Contribution

It proposes a novel classification scheme for sequential circuits focusing on input referencing, challenging the traditional synchronous versus asynchronous categorization.

Findings

Unified classification for synchronous and multi-clock domain circuits

Identification of subsets of past inputs used by sequential circuits

Clarification of how input referencing affects circuit behavior

Abstract

In sequential circuits, the current output may depend on both past and current inputs. However, certain kinds of sequential circuits do not refer to all of the past inputs to generate the current output; they only refer to a subset of past inputs. This paper investigates which subset of past inputs a sequential circuit refers to, and proposes a new classification of sequential circuits based on this criterion. The conventional classification of sequential circuits distinguishes between synchronous and asynchronous circuits. In contrast, the new classification consolidates synchronous circuits and multiple clock domain circuits into the same category.