RF/DC Switching Circuit With Low-Pass Isolation for Stable Testing
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Solution Overview
Problem
The accuracy of switching devices used in semiconductor test apparatuses deteriorates over time due to increased contact resistance in C-contact type relays, affecting both RF and DC tests, especially as the frequency of switching between test circuits increases.
Innovation Solution
Incorporating a low-pass filter and a switching section that isolates the RF and DC signals, allowing the RF signal to pass through during RF tests and the DC signal to pass through during DC tests, thereby preventing signal interference and maintaining accuracy even as the switching section wears out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a C-contact type relay is used to switch between RF test and DC test circuits, then the switching device can effectively switch between different test modes, but the contact resistance increases over time due to frequent switching, leading to deterioration of measurement accuracy
Solution Approach 1:
The patent segments the test signal paths by introducing a low-pass filter that separates the RF signal path from the DC measurement path. The filter divides the circuit into two independent paths: one for RF signals (through the relay) and one for DC signals (bypassing the relay), thereby eliminating the degradation effect on DC measurements while maintaining switching capability for RF tests.
Solution Approach 2:
The low-pass filter acts as an intermediary element between the switching relay and the DC measurement circuit. It allows DC signals to pass through to the measurement circuit while blocking RF signals, and simultaneously allows RF signals to pass through to the relay for switching operations. This intermediary component protects the measurement system from the harmful effects of relay contact degradation.
2Adaptability or versatility
If the switching device is used for long-term testing with frequent switching, then comprehensive test coverage is achieved, but the contact wear leads to unstable measurements and reduced reliability
Solution Approach 1:
The patent segments the signal transmission paths to create independent channels for RF and DC signals. This segmentation ensures that the reliability of DC measurements is not affected by the wear and tear of the switching relay, as DC signals bypass the relay through the low-pass filter. The system can thus achieve comprehensive test coverage while maintaining stable and reliable measurements throughout the device's operational life.
3Ease of operation
If the switching section is used to connect RF test circuits, then RF signal transmission is enabled, but RF signals may interfere with DC measurements when the switching section is in transition or off state
Solution Approach 1:
The low-pass filter serves as an intermediary that selectively passes DC signals while blocking RF signals from reaching the measurement circuit. During RF testing, the filter prevents RF signals from interfering with DC measurement paths. During DC testing, the filter allows DC signals to pass through to the measurement circuit while blocking any RF signals that may be present, thereby eliminating signal interference issues.
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 configuration ensures stable and accurate measurements during both RF and DC tests, even after long-term use, by preventing RF signals from interfering with DC measurements and vice versa, thus maintaining measurement precision.
Implementation Method 1
a first low-pass filter connected to the first DUT terminal and the first DC terminal
Data Source
AI summary
A switching device includes a base, a first DUT terminal, a first DC terminal, a first RF terminal, a first low-pass filter, and a first switching section. The first DUT terminal is a terminal for a device under test and is arranged on the base. The first DC terminal is a terminal for a DC test and is arranged on the base. The first RF terminal is a terminal for an RF test and is arranged on the base. The first low-pass filter is connected to the first DUT terminal and the first DC terminal. The first switching section is switchable between an on state and an off state. The first switching section electrically connects the first DUT terminal and the first RF terminal in the on state. The first switching section electrically disconnects the first DUT terminal and the first RF terminal in the off state.