Segmented SCR Structure for Noise Immunity and Low Shunt Current
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Solution Overview
Problem
Silicon Controlled Rectifiers (SCRs) are sensitive to noise due to their low gate current activation, leading to mis-triggering and circuit malfunctions in applications.
Innovation Solution
The design of the SCR is enhanced by splitting the N+ region closest to the cathode into partitioned regions and adding an additional N+ region below the gate, eliminating shunt current and improving noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SCR uses a conventional structure with low gate current activation, then the device can be easily activated, but the device becomes sensitive to noise causing mis-triggering
Solution Approach 1:
The N+ region closest to the cathode is divided into multiple partitioned regions (first N+ region and second N+ region), with an intermediate P region between them. This segmentation creates separate current paths: one for legitimate gate activation and another that blocks noise-induced shunt current, thereby maintaining ease of activation while improving noise immunity
Solution Approach 2:
An intermediate P region is introduced between the first N+ region (connected to cathode) and the second N+ region (connected to gate). This intermediary P region acts as a barrier that prevents direct shunt current flow between cathode and gate, blocking noise paths while allowing controlled gate activation through the designated gate terminal
2Device complexity
If the SCR has a simple N+ region structure, then the device complexity is low, but shunt current flows causing mis-triggering
Solution Approach 1:
The N+ region is segmented into multiple parts (first N+ region connected to cathode, second N+ region connected to gate) separated by an intermediate P region. This segmentation structure physically blocks the shunt current path that would otherwise flow directly between cathode and gate, eliminating the harmful effect while maintaining reasonable structural complexity
Solution Approach 2:
The harmful shunt current path is effectively removed from the device structure by introducing the intermediate P region between the N+ regions. This extraction of the harmful current path prevents mis-triggering while the overall device structure remains relatively simple and manufacturable
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
A silicon controlled rectifier includes a first P region (308), an N- region (310), a second P region (312), and a plurality of N+ regions (314a-e, 328). The first P region is connected to an anode (302). The N- region is adjacent the first P region. The second P region is adjacent the N- region such that the N- region is sandwiched between the first P region and the second P region. The plurality of N+ regions are disposed within the second P region. A first N+ region (314a-e) of the plurality of N+ regions is connected to a cathode (304). A second N+ region (328) of the plurality of N+ regions is connected to a gate (306). The device has a low shunt-current.