Three Terminal PIN Diode for Low Loss RF Switching
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Solution Overview
Problem
Impedance matching devices used in plasma processing chambers face challenges in efficiently switching capacitors to tune impedance matches, leading to high losses and complex isolation circuitry when used for AC or RF current switching.
Innovation Solution
A three-terminal PIN diode structure is introduced, incorporating an intrinsic region between the collector and base of a BJT, allowing a small DC bias to control a large AC current, reducing on-state losses and off-state capacitance, and eliminating the need for complex isolation circuitry by functioning like a PIN diode without requiring DC current through the collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional BJTs are used to switch AC or RF current, then the device can control current flow, but on-state losses increase and complex isolation circuitry is required
Solution Approach 1:
The patent merges the advantages of PIN diodes (low on-state losses, simple structure) with the three-terminal control capability of BJTs. By incorporating an intrinsic region between the collector and base, the device combines the low-loss conduction path of PIN diodes with the controlled switching capability of BJTs, eliminating the need for complex isolation circuitry while reducing on-state losses.
Solution Approach 2:
The device uses a composite semiconductor structure combining doped regions (emitter, base, collector) with an intrinsic region. This composite structure creates a hybrid device that exhibits both PIN diode characteristics (low on-state losses due to carrier storage in the intrinsic region) and BJT characteristics (three-terminal control), resolving the contradiction between loss reduction and control capability.
2Loss of energy
If PIN diodes are used for AC switching, then on-state losses are reduced, but DC current must flow through the device to maintain conduction
Solution Approach 1:
The intrinsic region acts as an intermediary that stores carriers, allowing the device to maintain low on-state losses without requiring continuous DC current through the collector. The carrier storage in the intrinsic region enables the device to function like a PIN diode with low losses while the base terminal provides control without requiring DC current flow through the entire device path.
3Productivity
If traditional switches are used for impedance matching, then capacitor switching is achieved, but off-state capacitance remains high causing losses
Solution Approach 1:
The device changes the capacitance parameter dynamically through bias control. In the off-state, the intrinsic region is depleted, presenting low capacitance to minimize off-state losses. When switched on, carriers are injected into the intrinsic region, changing the capacitance to enable low-loss conduction. This parameter change resolves the contradiction between maintaining impedance matching capability and reducing off-state losses.
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
The three-terminal PIN diode achieves low on-state losses and high current-carrying capacity similar to a PIN diode while maintaining low leakage current and high voltage capacity, with reduced off-state losses and simplified circuitry compared to traditional BJTs.
Implementation Method 1
A three-terminal PIN diode structure is introduced, incorporating an intrinsic region between the collector and base of a BJT, allowing a small DC bias to control a large AC current
Implementation Method 2
reducing on-state losses and off-state capacitance, and eliminating the need for complex isolation circuitry by functioning like a PIN diode
Data Source
AI summary
This disclosure describes a switch having a collector, base, emitter, and an intrinsic region between the collector and base. The intrinsic region increases the efficiency of the switch and reduces losses. The collector, base, and emitter each have respective terminals, and an AC component of current passing through the base terminal is greater than an AC component of current passing through the emitter terminal. Additionally, in an on-state a first alternating current between the base and collector terminals is greater than a second alternating current between the collector and emitter terminals. In other words, AC passes primarily between collector and base as controlled by a DC current between the base and emitter.