Semiconductor Switch Feedback Circuit for Leak Current Suppression
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Solution Overview
Problem
Current semiconductor switch circuits in wireless devices face challenges in maintaining high-voltage withstanding properties and linearity due to leak currents, which can lead to the parasitic bipolar transistor turning ON, especially when high-frequency signals are applied, causing distortion and reducing the switch circuit's performance.
Innovation Solution
The semiconductor device incorporates a feedback circuit with transistors and diodes configured in a specific manner to manage bias voltages and prevent the parasitic bipolar transistor from turning ON, using a series of transistors and diodes to control current flows and suppress bias voltage increases, thereby maintaining the switch circuit's high-voltage withstanding properties and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If transistors are used in switch circuits for high-frequency signals, then switching speed and frequency response are improved, but leak currents increase causing parasitic bipolar transistor activation and distortion
Solution Approach 1:
A feedback circuit is introduced as an intermediary mechanism that detects bias voltage changes caused by leak currents and actively compensates for them. The feedback circuit includes a detection transistor connected to the body of the main transistor, monitoring the bias voltage and generating a compensating signal to prevent parasitic bipolar transistor activation, thus resolving the contradiction between high-speed switching and leak current effects.
Solution Approach 2:
The patent implements a feedback mechanism where the bias voltage at the transistor body is continuously monitored through a feedback circuit. When leak currents cause bias voltage to shift toward turning on the parasitic bipolar transistor, the feedback circuit detects this change and adjusts the gate voltage accordingly to maintain the transistor in the desired off state, preventing distortion while maintaining high-frequency performance.
2Reliability
If feedback circuit is activated to suppress bias voltage increase, then linearity and high-voltage withstanding properties are improved, but device complexity increases
Solution Approach 1:
The feedback circuit is segmented into distinct functional components: a detection transistor connected to the body of the main transistor to monitor bias voltage, and a control mechanism that adjusts the gate voltage based on detected changes. This segmentation allows the feedback function to be integrated with minimal additional components, reducing the impact of complexity while maintaining reliability improvements.
3Strength
If multiple transistors are used in series coupling, then voltage withstanding capability is improved, but more leak current paths are created
Solution Approach 1:
The feedback mechanism is extended to monitor and compensate for bias voltage changes in each transistor within the series coupling chain. By detecting the cumulative effect of leak currents across multiple transistors and providing compensating gate voltages, the system maintains voltage withstanding capability while preventing the activation of parasitic bipolar transistors in any of the series-connected devices.
Data Source
AI summary
A semiconductor device includes an input terminal, an output terminal, and a plurality of transistors. The transistors are coupled through serial coupling. The transistors include a first transistor and a second transistor. The first transistor has a first end and a second end. The second transistor has a third end, a fourth end, a first gate, and a first body. The third end is coupled to the second end. The semiconductor device further includes a third transistor and a first diode. The third transistor and the first diode are serially coupled between the first body and the first end. The third transistor includes a second gate coupled to the first gate.