Switched Bypass Capacitor for PSRR Measurement
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Solution Overview
Problem
Conventional testing procedures for assessing semiconductor devices' susceptibility to AC interferers on DC supply lines are inadequate, particularly due to the complexity of integrated circuits, which can cause voltage drops leading to malfunctions and require disabling decoupling circuitry to accurately measure power supply rejection ratio (PSRR) without quick current variations.
Innovation Solution
A method and apparatus that utilize a switch device and capacitor to connect and disconnect from the DC line during testing, allowing for the application of a test signal and subsequent injection of an AC signal to assess the device's response without decoupling interference, thereby maintaining the device in a stable functional state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If decoupling circuitry is removed from the DC supply line to accurately measure PSRR, then measurement precision is improved, but device stability deteriorates due to quick current variations
Solution Approach 1:
The patent applies the dynamics principle by making the decoupling circuitry switchable rather than fixed. A switch device is introduced to dynamically control the connection state of the decoupling capacitor, allowing it to be connected during normal operation for stability and disconnected during PSRR measurement for accuracy. This dynamic configuration resolves the contradiction between measurement precision and device stability.
2Measurement precision
If decoupling circuitry is disabled during testing, then measurement accuracy is improved, but voltage drops cause malfunctions in other areas
Solution Approach 1:
The patent applies segmentation by dividing the testing process into distinct phases: a first part where the decoupling circuitry is enabled for stable operation, and a second part where it is disabled for accurate PSRR measurement. This temporal segmentation allows the system to maintain reliability during operation while achieving measurement accuracy during testing, resolving the contradiction between these two requirements.
3Adaptability or versatility
If a special test procedure is constructed to remove decoupling circuitry, then PSRR measurement capability is improved, but test complexity increases
Solution Approach 1:
The patent applies the merging principle by integrating the decoupling circuitry and switch device directly into the device under test (DUT). This integration allows the same hardware structure to serve both normal operation and PSRR measurement functions, eliminating the need for separate external test procedures and reducing overall test complexity while maintaining measurement capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate measurement of semiconductor devices' response to AC interferers on DC supply lines, ensuring proper functionality and reliability by controlling the decoupling structure's state during testing, thus overcoming the limitations of existing methods.
Implementation Method 1
electronic circuits typically include one or more decoupling capacitors for absorbing AC interference present on a DC supply line
Implementation Method 2
a switch device configured to electrically connect the capacitor to the DC line or electrically disconnect the capacitor from the DC line, depending on a state of the switch device
Data Source
AI summary
A method of testing a semiconductor device having a DC line configured to carry either a DC signal or a DC voltage and a circuit electrically connected to the DC line includes: during a first part of a test sequence, enabling a switch device so as to electrically connect a capacitor to the DC line via the switch device and applying a test signal to the circuit while the capacitor is electrically connected to the DC line; and during a second part of the test sequence, disabling the switch device so as to electrically disconnect the capacitor from the DC line via the switch device, injecting an AC signal onto the DC line after the capacitor is electrically disconnected from the DC line, and measuring a response of the circuit to the AC signal.