Asynchronous Input Delay Measurement Circuit
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Solution Overview
Problem
Conventional techniques for measuring signal propagation delays in IC devices face challenges, particularly with asynchronous test circuits, as they require precise timing for initialization signals, which can be difficult to implement effectively.
Innovation Solution
A system that measures propagation delays between asynchronous inputs and outputs of test circuits without toggling the clock input, using an oscillator circuit with stages connected in a chain, where each stage includes asynchronous test circuits, allowing re-initialization of test circuit outputs using secondary asynchronous inputs, thereby simplifying the circuitry and easing timing constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional techniques are used to measure propagation delays in asynchronous test circuits, then measurement capability is provided, but precise timing mechanisms are required which make implementation difficult
Solution Approach 1:
The patent extracts the clock input function from the initialization process. Instead of using a clock signal to initialize the asynchronous test circuit, the invention uses only asynchronous inputs (such as clear and set signals) to initialize and measure the circuit. This removes the need for complex timing mechanisms while maintaining measurement capability.
Solution Approach 2:
The patent introduces a secondary asynchronous input as an intermediary for initialization. By using a second asynchronous input (e.g., set signal when clear is used for measurement, or vice versa) to initialize the circuit state, the invention eliminates the need for precisely timed clocked initialization signals while still achieving proper circuit state preparation.
2Ease of operation
If additional circuitry is added to provide initialization signals to asynchronous inputs, then test circuit initialization is enabled, but circuit complexity increases
Solution Approach 1:
The patent makes the asynchronous inputs multi-functional. The same asynchronous inputs that are used for normal circuit operation are also used for initialization and measurement purposes. This eliminates the need for separate initialization circuitry while maintaining ease of operation, as the existing asynchronous input structure serves multiple functions.
Solution Approach 2:
The test circuit initializes itself using its own asynchronous inputs without requiring external initialization circuitry. By leveraging the inherent asynchronous input capabilities of the test circuit, the invention enables self-initialization, reducing overall circuit complexity while maintaining operational ease.
3Stability of the object's composition
If clock input is toggled to re-initialize test circuit, then test circuit state is reset, but measurement accuracy is compromised due to timing constraints
Solution Approach 1:
The patent removes the clock input from the initialization process entirely. By extracting the clock function from the state reset operation and using only asynchronous inputs for initialization, the invention eliminates timing constraints that would otherwise compromise measurement precision. The test circuit state is stabilized through asynchronous signal transitions rather than clocked operations.
Data Source
AI summary
A system measures propagation delays in any number of test circuits, each having two asynchronous inputs and an output, without using their clock inputs to re-initialize the test circuits during measurement operations. The delay between one of the test circuit's asynchronous inputs and its output is measured by propagating a test signal from the one asynchronous input to the output, and the test circuit is re-initialized using the test circuit's other asynchronous input.