Flip-Flop Scan Chain Layout for Two-Pattern Testing

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Solution Overview

Problem

Existing semiconductor integrated circuits are unable to perform two-pattern tests without increasing the occupied space, as they require additional test latches that consume more space.

Innovation Solution

A semiconductor integrated circuit design that includes a plurality of flip-flops and selectors, where each flip-flop has a master latch and a slave latch, and at least one selector is connected to the master latch of a different flip-flop, allowing for the creation of a scan chain that enables both one-pattern and two-pattern tests without significant space increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a test latch is provided in each flip-flop to enable two-pattern test, then two-pattern test capability is achieved, but the occupied space of the flip-flop increases

Engineering Contradiction:

Improvetwo-pattern test capabilityVSAvoidoccupied space of flip-flop

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The selector, originally designed for normal operation control, is made to serve dual purposes: controlling data input during normal operation and enabling test signal input during inspection mode. This multi-functionality eliminates the need for separate test latches, achieving two-pattern test capability without increasing flip-flop space

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention merges the test control function into the existing selector structure by adding a test signal input terminal. The selector combines normal operation control and test signal selection into a single component, integrating test functionality without requiring additional test latches in each flip-flop

Inventive Principle:

Principle #5Merging (Combining)

2Area of stationary object

If the circuit configuration is simplified to reduce space, then occupied space is reduced, but two-pattern test capability is lost

Engineering Contradiction:

Improveoccupied spaceVSAvoidtwo-pattern test capability

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The selector is designed to perform multiple functions: normal operation control and test signal input selection. By making the selector universal, the circuit maintains simplicity and compactness while achieving two-pattern test capability through the same existing components

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7945829B2Semiconductor integrated circuit

Publication Date: 2011.05.17 RAKUTEN GROUP INC

AI summary

[PROBLEMS] To provide a semiconductor integrated circuit by which what has been referred to as two-pattern test is made possible without greatly increasing an occupying area. [MEANS FOR SOLVING PROBLEMS] The semiconductor integrated circuit is provided with a plurality of flip-flop circuits and selectors corresponding to each flip-flop circuit. Each flip-flop circuit is provided with a master latch and a slave latch connected to the master latch. The selector is electrically connected with the master latch of the flip-flop circuit to which the selector corresponds, and is also connected with the master latch of the flip-flop circuit other than the one to which the selector corresponds.