DC-DC Converter Voltage Drop Reduction via Segmented Pumping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional DC-DC converting circuits in liquid crystal display panels suffer from voltage drop due to threshold voltage and low electric power efficiency, especially as the number of pumping circuits increases and voltage levels rise.
Innovation Solution
A DC-DC converting circuit with a charge pumping part, an output part, and a level boosting part, utilizing polysilicon PMOS transistors and clock signals to boost input voltage levels, preventing voltage drop and enhancing efficiency by controlling the drive of the charge pumping part with opposing clock phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional DC-DC converting circuit uses polysilicon PMOS transistors with diode-connected structure to simplify manufacturing, then ease of manufacture is improved, but voltage drop occurs due to threshold voltage and electric power efficiency deteriorates to 50% or less
Solution Approach 1:
The DC-DC converting circuit is divided into multiple pumping circuits (first pumping circuit and second pumping circuit) that operate in parallel with opposite clock phases. This segmentation allows voltage boosting without cascading, reducing the cumulative threshold voltage drop while maintaining manufacturing simplicity using polysilicon PMOS transistors.
Solution Approach 2:
The circuit uses periodic clock signals with opposite phases (first clock and second clock) to control the pumping circuits alternately. This periodic action enables continuous voltage boosting while allowing capacitors to charge and discharge in a controlled manner, improving efficiency by preventing threshold voltage accumulation.
2Power
If the number of pumping circuits increases to achieve higher output voltage, then output voltage level is improved, but voltage drop increases and electric power efficiency becomes lower
Solution Approach 1:
Instead of cascading pumping circuits in series which would accumulate threshold voltage drops, the invention segments the voltage boosting function into parallel pumping circuits that operate simultaneously with opposite clock phases. This achieves higher output voltage without increasing the number of series-connected stages, thereby maintaining efficiency.
Solution Approach 2:
The circuit dynamically switches between different pumping circuits using clock signals with opposite phases. The first pumping circuit operates during the high period of the first clock, while the second pumping circuit operates during the high period of the second clock, enabling continuous voltage boosting with minimal loss.
3Device complexity
If polysilicon PMOS transistors are used to build DC-DC converting circuit in liquid crystal display panel, then device complexity is reduced and manufacturing is simplified, but threshold voltage causes significant voltage drop in output
Solution Approach 1:
The output voltage is generated by combining voltages from multiple pumping circuits rather than using a single long cascade. This segmentation prevents the cumulative threshold voltage drop that would occur in a single long chain of polysilicon PMOS transistors, maintaining output stability while keeping the circuit simple.
Solution Approach 2:
Capacitors are used as intermediaries to store and transfer voltage between the pumping circuits and the output. This allows the circuit to overcome the threshold voltage limitations of polysilicon PMOS transistors by using capacitive coupling rather than direct transistor cascading.
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 solution achieves an output voltage level twice that of the input voltage, improving electric power efficiency to 77% and minimizing voltage drop caused by threshold voltage, while simplifying the manufacturing process by using polysilicon PMOS transistors.
Implementation Method 1
a charge pumping part, an output part, and a level boosting part. The charge pumping part receives an input voltage, a first clock and a second clock having a phase opposite to the first clock that are externally supplied, outputs a first voltage boosted by a high voltage of the first clock with respect to the input voltage during a high period of the first clock
Data Source
AI summary
In a DC-DC converting circuit, a charge pumping part receives an input voltage, a first clock and a second clock and outputs first and second voltages to first and second nodes, which are boosted by high voltages of the first and second clocks with respect to the input voltage. An output part is connected to the first and second nodes of the charge pumping part, and a level boosting part turns on or turns off the charge pumping part in response to the first and second clocks. The output part outputs the first and second voltages through an output terminal during a high period of the first clock and during a high period of the second clock, respectively. Thus, an output voltage having a voltage level corresponding to two times that of the input voltage may be output from the output terminal while the first and second clocks are provided.