Charge Pump Bottom Plate Charging for Low Output Ripple
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Solution Overview
Problem
Charge pump circuits experience significant output ripple due to parasitic capacitance at the terminals of capacitors, which is exacerbated by the need to charge these capacitances, leading to inefficiencies and increased circuit size and cost.
Innovation Solution
The integration of a bottom plate charger circuit that detects reverse current flow and provides additional charging current to parasitic capacitances, reducing the impact of parasitic capacitance on output voltage ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If switched capacitors are used to generate output voltage, then voltage conversion is achieved, but parasitic capacitance causes significant output ripple
Solution Approach 1:
The patent extracts the harmful effect of parasitic capacitance by introducing a separate bottom plate charger circuit that specifically targets and charges the parasitic capacitance at the bottom plate of the first capacitor. This isolates the harmful effect from the main charge pump operation, allowing the switched capacitor to perform voltage conversion while the dedicated charger handles the ripple reduction.
Solution Approach 2:
The bottom plate charger circuit performs preliminary charging of the parasitic capacitance before the main charge pump operation would cause discharge. By detecting reverse current flow and proactively charging the parasitic capacitance through the current source, the circuit prevents the capacitance from discharging during normal operation, thereby reducing output voltage ripple.
2Object-generated harmful factors
If additional current is provided to charge parasitic capacitance, then output ripple is reduced, but circuit complexity increases
Solution Approach 1:
The bottom plate charger circuit is designed to be activated only when reverse current is detected, making it a multi-functional addition that serves both normal charge pump operation and ripple reduction. The same circuit structure handles both the detection of parasitic capacitance discharge and the provision of compensating current, avoiding the need for completely separate control mechanisms.
Solution Approach 2:
The bottom plate charger circuit automatically activates based on reverse current detection without requiring external control signals. The circuit monitors its own operating conditions and self-regulates the charging of parasitic capacitance, reducing the need for additional control circuitry and simplifying the overall system architecture.
3Stability of the object's composition
If reverse current flows to charge parasitic capacitance, then capacitance is charged, but efficiency is reduced due to current loss
Solution Approach 1:
The bottom plate charger circuit incorporates feedback through reverse current detection. When the switching circuit attempts to discharge the first capacitor and reverse current flows, the detection circuit senses this condition and activates the current source to provide compensating charge. This feedback mechanism ensures that parasitic capacitance is charged only when necessary, minimizing energy loss by avoiding continuous charging operations.
Solution Approach 2:
The patent converts the harmful reverse current flow into a useful signal for controlling the bottom plate charger. Instead of simply suppressing reverse current, the circuit uses the reverse current detection to trigger precise charging operations, transforming the harmful effect into a control mechanism that improves overall efficiency by charging parasitic capacitance only when needed.
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 bottom plate charger circuit significantly reduces output voltage ripple, enhancing efficiency and reducing the size and cost of the charge pump circuit by minimizing current flow to charge parasitic capacitances.
Implementation Method 1
Charge pump circuits experience significant output ripple due to parasitic capacitance at the terminals of capacitors
Data Source
AI summary
An apparatus includes first and second capacitors, first and second switches, a current source, a first circuit, and a second circuit. The first switch is coupled between a first terminal of the first capacitor and a reference terminal. The current source has an input coupled to a power terminal. The second switch is coupled between the first terminal of the first capacitor and an output of the current source. The second capacitor has a first terminal coupled to the reference terminal. The first circuit has a first terminal coupled to a second terminal of the second capacitor, and a second terminal coupled to a second terminal of the first capacitor. The second circuit has a first input coupled to a third terminal of the first circuit, a second input coupled to the power terminal, and an output coupled to the output of the current source.