Integrated Circuit Test Current Control for Class-D Output Switches
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Solution Overview
Problem
The existing methods for testing integrated circuits with class-D amplifiers are limited by the need for external hardware, slow measurement procedures, and limited parallel testing capabilities due to the use of external switchable resistors and relays, which increase testing time and cost.
Innovation Solution
The integration of a current source within the integrated circuit, utilizing either a pair of switching devices or a plurality of pairs, allows for the elimination of external components and relays, enabling faster and more accurate testing by using the over-current detection circuit for current regulation and distribution of power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external switchable resistors and relays are used for current control during testing, then the testing can be performed with standard equipment, but the testing time increases and productivity decreases
Solution Approach 1:
The patent combines the current source functionality with the switching devices already present on the integrated circuit. The second switching device is configured to operate as a current source for testing the first switching device, eliminating the need for external switchable resistors and relays. This integration merges multiple functions (switching and current sourcing) into a single component, thereby reducing external hardware requirements and accelerating the testing process by removing mechanical relay switching delays.
2Productivity
If multiple DUTs are contacted with one single probe card for parallel testing, then productivity increases, but the amount of space on the handler is limited
Solution Approach 1:
The patent makes the switching devices serve multiple functions: they operate as power switches during normal operation and as integrated current sources during testing. This multi-functionality eliminates the need for dedicated external current sourcing hardware, reducing the space requirements on the handler and enabling more DUTs to be tested in parallel with a single probe card while maintaining full testing capability.
3Reliability
If the current is increased stepwise by closing relays, then the measurement can be performed safely, but the measurement speed decreases and time is lost
Solution Approach 1:
The patent replaces the mechanical relay system with an electronically controlled switching mechanism. The second switching device is controlled by a test controller to operate as a current source, providing electronic control of test current without mechanical moving parts. This substitution eliminates relay closing delays and mechanical wear, enabling faster, safer, and more reliable current control during testing while maintaining the ability to perform stepwise current increases for safety.
4Measurement precision
If external hardware is used for on-resistance measurements, then the measurements can be performed with standard equipment, but the hardware complexity increases and device complexity increases
Solution Approach 1:
The patent extracts the current sourcing functionality from external hardware and integrates it directly into the switching devices on the integrated circuit. By configuring the second switching device as an on-chip current source, the patent eliminates the need for external switchable resistors, relays, and associated control hardware. This extraction of functionality to the device level simplifies the external testing hardware while maintaining precise on-resistance measurement capability through the integrated current control.
Data Source
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AI summary
An integrated circuit comprising a first pair (11, 12) of switching devices arranged in series between positive and negative supply terminals is disclosed. The integrated circuit is switchable between an operational mode, in which the first pair (11, 12) of switching devices are driven to couple either the positive or negative supply terminal to an output terminal, and a test mode, in which a current source on the integrated circuit is driven to cause a desired current to flow in a first one (12) of the first pair (11, 12) of switching devices.