Reset scheme for scan chains with asynchronous reset signals

摘要

A first apparatus includes at least one scan chain. Each of the at least one scan chain includes scan cells coupled together. Each scan cell in the at least one scan chain includes a first type of scan cell when a reset state of the scan cell is a first state, and a second type of scan cell when the reset state of the scan cell is a second state. One or more scan chains of the at least one scan chain includes at least one of the first type of scan cell and at least one of the second type of scan cell. A second apparatus includes first and second sets of scan chains including flip-flops without both set and reset functionality. Each of the flip-flops in the first and second sets of scan chains has a reset state of a first state and a second state, respectively.

主权项

1. An apparatus comprising at least one scan chain, each of the at least one scan chain comprising a plurality of scan cells coupled together, wherein each scan cell in the at least one scan chain comprises:
a first type of scan cell when a reset state of the scan cell is a first state, the first type of scan cell comprising a first-type flip-flop without both built-in set and reset circuitry; and a second type of scan cell different than the first type of scan cell when the reset state of the scan cell is a second state, the second type of scan cell comprising a second-type flip-flop with at least one of built-in set or reset circuitry, wherein one or more scan chains of the at least one scan chain comprises at least one of the first type of scan cell and at least one of the second type of scan cell, the one or more scan chains comprising scan cells in which each scan cell is one of the first type of scan cell or the second type of scan cell depending on whether the reset state of the scan cell is the first state or the second state, respectively.