Active Diode Circuit with Current Mirror Control
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Solution Overview
Problem
Existing diode circuits in power management applications suffer from high power loss and diode voltage due to inefficient control mechanisms, particularly in low power applications, leading to decreased efficiency and increased complexity.
Innovation Solution
An active diode circuit with a control circuit comprising a current mirror and MOSFETs, where the control current is proportional to the diode current, and the diode voltage is maintained below a predetermined threshold, using a dual transistor structure to minimize power loss and maintain similar reverse current to common semiconductor diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If voltage driven MOS switches with active amplifiers are used to minimize diode voltage, then power loss is reduced, but biasing currents are required which decrease power efficiency
Solution Approach 1:
The control circuit automatically generates the control current for the MOS switch using the diode current itself through a current mirror configuration. The circuit extracts a portion of the diode current (via transistor ratio α) to drive the MOS gate, eliminating the need for external biasing currents while maintaining low diode voltage operation
Solution Approach 2:
The invention changes the control parameter from voltage-driven to current-driven operation. By using a current mirror to generate the gate control current proportionally from the diode current, the system adapts the control signal parameters to match the operating conditions, enabling efficient operation across different current levels without requiring fixed biasing currents
2Ease of operation
If voltage driven MOS switches with hard voltage switching are used, then switching control is achieved, but offset causes too late or too early switching which decreases power efficiency
Solution Approach 1:
The control circuit uses the diode current itself as feedback to generate the control signal. The current mirror configuration continuously monitors the diode current and automatically adjusts the MOS gate control current in real-time, eliminating offset errors and ensuring switching occurs at the precise moment when diode current becomes zero, thereby maximizing power efficiency
3Loss of energy
If active MOS or bipolar switches replace diodes in DC-DC converters, then forward voltage is reduced, but additional control circuits are required which increase complexity
Solution Approach 1:
The invention merges the diode function with the MOS switch control function into a single integrated structure. The current mirror control circuit is directly coupled to the MOS switch, combining the rectification function with the active control function in one unit, thereby reducing overall system complexity compared to separate diode replacement approaches
Solution Approach 2:
The active diode circuit serves multiple functions: it provides rectification like a traditional diode, actively controls the MOS switch timing, generates its own control signals, and adapts to varying current conditions. This multi-functionality eliminates the need for separate control circuits while achieving lower forward voltage drops
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 active diode circuit significantly reduces power loss and diode voltage by an order of magnitude while maintaining similar reverse current, enhancing efficiency in applications like AC-DC rectification, DC-DC converters, and battery protection.
Implementation Method 1
a control circuit comprising a current mirror circuit connected across the anode or cathode and the control terminal, the current mirror circuit configured to generate a control current of the active diode on the control terminal proportional to the diode current of the active diode
Implementation Method 2
a first MOSFET of a first conductivity type; and a second MOSFET of the first conductivity type, wherein the source of the first and second MOSFETs are connected to form one of the anode and cathode of the active diode, the gate and drain of the second MOSFET is connected to the gate of the first MOSFET
Data Source
Figure 1~2
Figure 3a~3d
Figure 4
AI summary
An active diode circuit comprising: an active diode 300, the active diode comprising an anode terminal 305, a cathode terminal 307 and a control terminal 309; a control circuit 500 configured to generate a control current of the active diode on the control terminal proportional to the diode current of the active diode, and to control the diode voltage of the active diode below a predetermined threshold.