Switched-Capacitor Charge Pump With Wide DC Output Range
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Solution Overview
Problem
Traditional charge pump circuits have a limited amplitude range of DC output, restricting the frequency range of PLL-VCO circuits and suffering from electrical performance issues due to the mismatch between PMOS and NMOS current sources.
Innovation Solution
A switched-capacitor charge pump device with two switched-capacitor circuits and an output capacitor circuit, utilizing a Schmitt trigger for voltage comparison and switching between full-amplitude and half-amplitude drive voltages, eliminates the need for different MOS type current sources, enabling a wider amplitude range of DC output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional charge pump circuits use both PMOS-based and NMOS-based current sources, then the circuit can provide both pump-up and pump-down functions, but electrical performance deteriorates due to mismatch between different MOS types
Solution Approach 1:
The patent uses two current sources of the same MOS type (both NMOS or both PMOS) instead of mixing different types. This homogeneous design eliminates the electrical characteristic mismatch between different MOS types while maintaining both pump-up and pump-down functions through complementary switching control.
2Device complexity
If traditional charge pump circuits are designed with limited amplitude range, then circuit complexity is reduced, but the frequency range of PLL-VCO circuits is restricted
Solution Approach 1:
The patent implements dynamic voltage amplitude adjustment by switching between full-amplitude (Vdd) and half-amplitude (Vdd/2) drive voltages based on the output voltage level. This dynamic adaptation allows the circuit to achieve wide output amplitude range (0.25Vdd to 1.25Vdd) without significantly increasing circuit complexity, as it uses simple voltage comparison and switching control.
3Adaptability or versatility
If switched-capacitor circuits switch between full-amplitude and half-amplitude drive voltages, then output DC voltage amplitude range is widened, but switching control complexity increases
Solution Approach 1:
The patent employs feedback control where the output voltage is continuously monitored and compared against reference levels (Vdd/2). Based on this feedback, the switching control unit adjusts the drive voltage amplitude dynamically - using full-amplitude when output is below threshold and half-amplitude when above threshold - to maintain output voltage within the desired range (0.25Vdd to 1.25Vdd).
Solution Approach 2:
The patent introduces an intermediary voltage level (Vdd/2) as a reference threshold for control. This intermediary level serves as a mediator between the full-amplitude drive (Vdd) and the desired output range, enabling smooth transitions and precise control of the output voltage amplitude without requiring complex direct control mechanisms.
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 provides a DC voltage amplitude range from -0.1 V to +1.1 V, significantly broader than traditional charge pumps, and avoids electrical characteristic mismatches by using same-type current sources, enhancing the frequency range and performance of PLL-VCO circuits.
Implementation Method 1
a first switched-capacitor circuit (141) and a second switched-capacitor circuit (142)... an output capacitor circuit (150)
Data Source
AI summary
A switched-capacitor charge pump device is proposed, which is designed for integration to a circuit system, such as a PLL (phase-locked loop) circuit system, for generation of an output direct-current (DC) voltage with a wide amplitude range; and which is characterized by the utilization of two switched-capacitor circuit units in addition to the output capacitor circuit and the utilization of an output voltage comparing circuit (such as a Schmitt trigger) for comparing the end-result output DC voltage against a half-amplitude drive voltage such that when the switched-capacitor circuit units are subjected to a charging-discharging action for voltage pump-up or pump down operations, the switched-capacitor circuit units are switched between a full-amplitude drive voltage and a half-amplitude drive voltage. This feature allows the invention to provide an output DC voltage with a wider amplitude range than prior art.