Low-Voltage-Drop Rectifier Circuit Using MOSFETs and Comparator
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Solution Overview
Problem
Schottky diodes, with their low forward bias voltage, are not readily available using CMOS manufacturing processes, leading to large layout areas on PCBs when implemented as discrete components, necessitating a solution for low-voltage-drop rectification.
Innovation Solution
A low-voltage-drop rectifier circuit comprising MOSFETs, a comparator, and a level adjustment circuit, which compares input and output voltages to generate control voltages that fine-tune the voltage drop between them, effectively mimicking a Schottky diode's behavior while being compatible with CMOS processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a Schottky diode is implemented with a discrete component, then the forward bias voltage is low (0.1V to 0.2V), but the layout area on PCB is large
Solution Approach 1:
The patent merges multiple MOSFETs (first and second MOSFETs with source terminals connected together) to create an integrated rectifier circuit that replaces the discrete Schottky diode. This consolidation achieves low voltage drop characteristics while reducing the overall layout area by integrating functions into a single circuit block on the PCB.
Solution Approach 2:
The rectifier circuit is designed to be compatible with general CMOS manufacturing processes, allowing it to serve multiple functions: achieving Schottky-like low voltage drop characteristics, integrating seamlessly with standard CMOS circuits, and reducing the need for separate discrete components. The circuit can be universally applied in various CMOS-based power management applications.
2Ease of manufacture
If a traditional diode is used, then the manufacturing process is simple, but the forward bias voltage is high (0.6V to 0.7V)
Solution Approach 1:
The patent changes the fundamental operating parameters of the rectifier by using MOSFETs in a specific configuration with controlled gate voltages. By dynamically controlling the gate-source voltage of the MOSFETs through comparison circuits, the circuit achieves a low effective forward bias voltage (0.1V to 0.2V) that is comparable to Schottky diodes, while maintaining compatibility with standard CMOS manufacturing processes.
3Use of energy by moving object
If a Schottky diode is used, then the forward bias voltage is low (0.1V to 0.2V), but it is not available using general CMOS manufacturing process
Solution Approach 1:
The patent creates a functional copy of the Schottky diode's low voltage drop characteristic using MOSFETs in a CMOS-compatible configuration. Instead of using actual Schottky diode structures that require special manufacturing processes, the circuit replicates the electrical behavior through controlled MOSFET operation, achieving the same low forward bias voltage (0.1V to 0.2V) while being fully compatible with general CMOS manufacturing processes.
Data Source
AI summary
A low-voltage-drop rectifier circuit includes a first MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a second MOSFET, a comparator, and a level adjustment circuit. The first MOSFET has a gate terminal for receiving a control voltage, a source terminal connected to a connection node, a drain terminal connected to an input node, and a body terminal connected to the connection node. The second MOSFET has a gate terminal for receiving the control voltage, a source terminal connected to an output node, a drain terminal connected to the connection node, and a body terminal connected to the output node. The comparator generates a first comparison voltage and a second comparison voltage according to an input voltage at the input node and an output voltage at the output node. The level adjustment circuit generates and fine-tunes the control voltage according to the first comparison voltage and the second comparison voltage.