Charge Pump Voltage Conversion Circuit for Miniaturization
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Solution Overview
Problem
Conventional charge pump DC-DC converters require large transistors and circuit sizes to achieve high current capacitance, which is problematic for miniaturization, especially when using low-mobility thin film transistors on insulating substrates, leading to increased frame sizes in displays.
Innovation Solution
A supply voltage conversion circuit using a charge pump circuit with a pair of transistors and a capacitor, where the amplitude of a control pulse is converted to increase the gate-source voltages of the transistors, reducing their on-resistance and allowing for smaller transistor sizes, thus achieving a large current capability with a small circuit scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large transistors are used to achieve high current capacitance in a charge pump circuit, then the current capability is improved, but the circuit size increases
Solution Approach 1:
The patent changes the voltage parameter by applying a control signal with amplitude corresponding to the second supply voltage (higher voltage) to the gates of the transistors. This voltage parameter change reduces the required transistor size for achieving the same current capability, as higher gate voltage provides stronger control over the channel, allowing smaller transistors to deliver the same current.
2Area of moving object
If the amplitude of control pulse is increased to reduce transistor size, then the transistor on-resistance decreases, but the control circuit complexity increases
Solution Approach 1:
The patent makes the control signal generation circuit universal by using the same control signal (with amplitude based on the second supply voltage) for controlling both the first and second transistors in the charge pump circuit. This multi-functional use of a single control signal approach simplifies the overall control circuit design while achieving the goal of reduced transistor size.
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 enables a charge pump circuit with a large current capability while maintaining a small circuit scale, which is particularly beneficial for miniaturization and cost reduction in portable terminals and displays.
Implementation Method 1
a charge pump circuit that includes a capacitor and a pair of transistors for charging/discharging the capacitor and converts a first supply voltage to a second supply voltage that is larger than the first supply voltage
Data Source
AI summary
A supply voltage conversion circuit allowing fabrication of a charge pump circuit having a large current capability with a small area is provided. In a charge pump DC-DC converter (10) for converting a supply voltage VDD1 to a supply voltage VDD2, a level shifter (12) implements amplitude conversion to convert from a control pulse with amplitude of VSS-VDD1 to a control pulse with amplitude of VSS-VDD2. By using the control pulse having the converted amplitude as a pumping pulse, a flying capacitor (C11) is charged/discharged by MOS transistors (Qp11), and (Qn11) of a charge pump circuit (11), and switching of MOS transistors (Qn12), and (Qp12) coupled to the output of the flying capacitor (C11) is controlled.