Back-to-Back Charge Pump with MOSFET Diodes for Low Forward Drop
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Solution Overview
Problem
Existing AC-to-DC charge pumps face inefficiencies due to high diode forward drops, which require high input voltages and limit power efficiency, especially in systems where the antenna signal is small and the tank circuit's resonant frequency needs to be dynamically tuned.
Innovation Solution
The implementation of a back-to-back configuration of charge pumps with current-source-biased MOSFET diodes, where diodes are used as either P-channel or N-channel MOSFETs depending on their position, reduces forward diode drops and enhances efficiency by eliminating substrate diode forward biasing and improving tuning of the tank circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional diodes are used in charge pump, then the structure is simple, but the forward diode drop is high which reduces power efficiency
Solution Approach 1:
The patent changes the fundamental parameter of the diode component by replacing conventional diodes with MOSFET diodes. This parameter change reduces the forward voltage drop from typical diode levels (0.7V or higher) to much lower levels, thereby improving power efficiency and reducing energy loss in the charge pump circuit.
Solution Approach 2:
The patent substitutes the mechanical/physical structure of conventional diodes with MOSFET-based diode structures. This substitution enables lower on-resistance and reduced forward voltage drop, directly addressing the power efficiency issue while maintaining the diode's essential function in the charge pump architecture.
2Power
If high input voltage is used to overcome diode forward drops, then the charge pump can operate, but the input voltage requirement increases which limits efficiency with small antenna signals
Solution Approach 1:
By changing the diode parameter to MOSFET diodes with lower forward voltage drop, the patent reduces the minimum input voltage requirement. This allows the charge pump to operate efficiently with smaller antenna signals that would otherwise be insufficient to overcome the higher forward drops of conventional diodes.
3Device complexity
If substrate diodes are forward biased in conventional charge pumps, then the circuit can be simplified, but power efficiency is reduced due to the forward bias loss
Solution Approach 1:
The patent substitutes MOSFET diodes for conventional diodes in positions where substrate diodes would be forward biased. This substitution eliminates the harmful forward bias effect while maintaining circuit simplicity, as the MOSFET diodes can be configured to avoid substrate diode conduction paths.
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 configuration achieves significantly improved power efficiency, allowing for stable voltage generation with reduced input voltage requirements and enhanced system stability, supporting target voltages and load currents at high efficiency.
Implementation Method 1
current-source-biased MOSFET diodes, where diodes are used as either P-channel or N-channel MOSFETs depending on their position
Implementation Method 2
an AC-to-DC charge pump draws power from an alternating current ('AC') source to develop one or more direct current ('DC') power supplies
Data Source
AI summary
An improved AC-to-DC charge pump for use, for example, in voltage generation circuits. In one embodiment, two 2-diode charge pumps are coupled in back-to-back configuration, and adapted to develop a substantially stable voltage on a mid-level rail. In one other embodiment, two 3-diode charge pumps are coupled in back-to-back configuration, and adapted also to develop a substantially stable voltage on a mid-level rail. In one preferred embodiment, all diodes are implemented as current-source-biased MOSFETs.