JFET High-Voltage Sensing Device for Power Converter Switch Control
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Solution Overview
Problem
Current power converter implementations face difficulties in achieving accurate and low-latency measurement of voltages and currents associated with high-side switches due to the absence of a fixed ground reference, leading to inefficiencies and inaccuracies in zero-volt switching and current-based control.
Innovation Solution
An integrated circuit with a high-voltage region including a junction-field effect transistor (JFET) and a voltage divider, configured to operate in pinch-off mode, provides a voltage indicative of the voltage differential between the drain and gate of the JFET, enabling accurate voltage and current sensing for high-side switch control, with a high-side driver circuit controlling the high-side switch based on this sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external voltage and current measurements are used for high-side switch sensing, then device complexity is reduced, but measurement precision and latency are insufficient
Solution Approach 1:
The patent merges the voltage sensing function and current sensing function into a single integrated sensing device located in the high-voltage region. The JFET-based sensing device simultaneously provides voltage differential measurement (between drain and gate) and current measurement capabilities, eliminating the need for separate external sensing circuits and improving measurement precision while maintaining compact integration.
Solution Approach 2:
The JFET operates in pinch-off mode as an intermediary element to sense both voltage and current parameters. By utilizing the JFET's channel characteristics and the voltage divider network, the device converts high-voltage domain signals into measurable parameters without requiring direct external measurement, thus achieving high precision sensing within the integrated circuit.
2Reliability
If edge sensing on switch node signal is used, then device complexity is minimized, but measurement precision and reliability are insufficient
Solution Approach 1:
The patent implements local quality by placing the sensing device directly in the high-voltage region near the high-side switch, allowing it to locally sense the voltage differential between drain and gate. This localized sensing provides more reliable and accurate switching control information compared to remote edge sensing, while the integrated structure maintains reasonable complexity.
Solution Approach 2:
The sensing device provides real-time feedback on the voltage differential and current status to the control circuitry. This feedback mechanism enables precise control of the high-side switch by continuously monitoring the actual switching conditions, improving reliability through closed-loop control rather than open-loop edge sensing.
3Loss of energy
If zero-volt switching control is implemented, then energy loss is reduced, but measurement precision requirements increase
Solution Approach 1:
The patent replaces traditional external voltage dividers and sensing circuits with a JFET-based sensing mechanism that operates directly in the high-voltage region. The JFET's inherent characteristics and integrated voltage divider provide the necessary voltage detection accuracy for zero-volt switching control, enabling precise energy optimization without external components.
4Loss of time
If integrated high-voltage sensing device is implemented, then measurement precision and latency are improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sensing functions (voltage sensing, current sensing, and switching control) into a single integrated device in the high-voltage region. This merging eliminates signal transmission delays to external sensors and reduces sensing latency, while the integrated structure manages complexity through functional consolidation rather than proliferation of separate components.
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 solution enables precise control of high-side switches, improving efficiency and reducing switching losses by allowing zero-volt switching and current-based control with low latency, enhancing performance and reliability in high-voltage power converters.
Implementation Method 1
The JFET can be configured to operate in pinch-off mode
Implementation Method 2
The voltage divider can include a first terminal coupled to a drain of the JFET, a second terminal coupled to a gate of the JFET, and a sense terminal
Data Source
AI summary
In a general aspect, an integrated circuit (IC) can include a low-voltage region including a low-side driver circuit configured to control a low-side switch of a power converter. The IC can also include a high-voltage region including a floating region of a first conductivity and a high-voltage sensing device disposed in the floating region. The high-voltage sensing device can include a junction-field effect transistor (JFET), and a voltage divider. The voltage divider can include a first terminal coupled to a drain of the JFET, a second terminal coupled to a gate of the JFET, and a sense terminal, the voltage divider being configured to a provide, on the sense terminal. The IC can further include a high-side driver circuit coupled with the sense terminal. The high-side driver circuit can be configured to control a high-side switch of the power converter based on the voltage on the sense terminal.