Low-Voltage Transistor Stress Test Circuit With Switched Resistance
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Solution Overview
Problem
Low voltage transistors in electronic circuits face challenges in stress testing due to their maximum voltage ratings being lower than the circuit's voltage domain, making it difficult to apply sufficient stress voltages during testing without overloading the resistive load, which can lead to inadequate evaluation of transistor quality and potential defects.
Innovation Solution
Incorporating a resistive circuit that provides different resistance values during normal and stress test modes, allowing for the application of stress voltages exceeding the maximum voltage ratings of transistors, with specific configurations for gate-source and source-drain stress tests using variable resistors and control signals to ensure adequate voltage drops across transistor terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stress voltage is applied to low voltage transistors during testing, then transistor quality evaluation is improved, but the resistive load becomes overloaded because the stress voltage exceeds the maximum voltage rating
Solution Approach 1:
The circuit is segmented into two distinct operational modes: normal operation mode and stress test mode. During normal operation, the resistive load operates within safe voltage limits. During stress testing, a separate test voltage source applies elevated voltage specifically to the transistor terminals while the resistive load is protected through circuit configuration, allowing independent optimization of each component's operating conditions.
Solution Approach 2:
A test voltage source acts as an intermediary element that enables stress testing without directly subjecting the resistive load to excessive voltage. The circuit configuration allows the test voltage to be applied across transistor terminals while current through the resistive load is limited to safe levels, serving as a mediator between the need for high stress voltage and the constraint of load protection.
2Reliability
If maximum voltage rating of transistor is lower than circuit voltage domain, then transistor can operate safely in low voltage mode, but stress testing cannot be performed effectively
Solution Approach 1:
The circuit dynamically switches between normal operation configuration and stress test configuration. Control signals enable the circuit to adapt its topology based on operational mode: during normal operation, the transistor operates safely within its voltage rating; during stress testing, the circuit reconfigures to allow elevated voltage application across transistor terminals through the test voltage source, providing both safety and testing capability.
Solution Approach 2:
The circuit design provides multi-functionality by integrating both normal operation and stress testing capabilities into a single circuit architecture. The same transistor and resistive load serve dual purposes: operating as a functional circuit element during normal operation and as a testable device during stress testing, eliminating the need for separate test equipment or circuit modifications.
3Measurement precision
If different resistance values are provided during normal and test modes, then adequate voltage drops can be achieved across transistor terminals, but circuit complexity increases
Solution Approach 1:
The resistive circuit parameters are changed based on operational mode. During normal operation, the resistive circuit provides a first resistance value optimized for functional performance. During stress testing, the resistive circuit is reconfigured to provide a second resistance value that enables adequate voltage drop across transistor terminals when subjected to elevated test voltages, allowing precise control of test conditions.
Data Source
AI summary
A current leg located in a voltage domain where the current leg includes a transistor of a current mirror having a maximum voltage rating of less than the voltage of the voltage domain. The current leg includes a resistive element circuit to provide a first resistance during a normal mode of operation of the current leg and a different resistance during of a stress test of the transistor in a test mode of the circuit.