High-Voltage Rectifier Using Standard CMOS Transistors
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Solution Overview
Problem
Existing high-voltage rectifiers in RFID electronic tags and smart cards face challenges in achieving high-voltage resistance using standard CMOS transistors without additional process complexity, leading to increased costs and reduced rectifier lifetime due to peak-peak voltages exceeding 10V.
Innovation Solution
A high-voltage-resistant rectifier design utilizing standard CMOS transistors with additional MOS transistors or capacitors connected in series to reduce voltage stress on gate and source terminals, allowing for effective division of AC input voltage, thereby enhancing voltage resistance without additional process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard low-voltage CMOS transistors are used in the rectifier, then manufacturing cost is reduced and process complexity is simplified, but the rectifier lifetime becomes extremely short due to gate oxide breakdown at high voltages
Solution Approach 1:
The rectifier circuit is segmented into multiple transistor stages. Standard CMOS transistors are used for normal operation, while a second stage with high-voltage capable transistors handles voltage breakdown protection. This segmentation allows the majority of the circuit to use inexpensive standard transistors while only critical components require high-voltage tolerance.
Solution Approach 2:
The circuit incorporates a protection mechanism that activates before the gate oxide breaks down. When voltage exceeds the threshold, the protection circuit conducts current through alternative paths, cushioning the standard transistors from destructive voltage spikes and preventing premature failure.
2Reliability
If high-voltage-resistant transistors are used in the rectifier, then the rectifier can withstand peak-peak voltages greater than 10V, but the manufacturing process becomes more complex and costly
Solution Approach 1:
High-voltage resistance is applied locally only to specific transistors that require it, rather than making all transistors high-voltage capable. The first stage uses standard transistors for normal operation, while only the second stage transistors are designed with high-voltage tolerance, optimizing both performance and manufacturing cost.
Solution Approach 2:
The rectifier employs a composite transistor architecture combining standard CMOS transistors and high-voltage transistors in different stages. This composite approach allows the circuit to achieve high-voltage resistance where needed while maintaining compatibility with standard manufacturing processes for the majority of components.
3Reliability
If thicker gate oxide is used to improve gate breakdown voltage, then voltage resistance is enhanced, but manufacturing process complexity increases
Solution Approach 1:
Thicker gate oxide is applied locally only to the second stage transistors that require high-voltage tolerance, while the first stage transistors use standard thin gate oxide for optimal performance. This localized approach enhances voltage resistance where needed without complicating the overall manufacturing process.
Data Source
AI summary
A high-voltage-resistant rectifier with standard CMOS transistors is disclosed in present invention. In a bridge full-wave rectifier comprising four MOS transistors, extra transistors are connected in series between the transistors which endure high voltage and the input to decrease the voltage imposed on the gate of them; moreover, the present invention provides a way to divide voltage imposed between the gate and the source of the said transistors by connecting in series with extra transistors, so it is achieved to implement a high-voltage-resistant rectifier with standard low voltage CMOS transistors without additional process complexity, and decreases manufacture and process costs.