Pump-Capacitor Oscillator Circuit for High-Voltage Sinewave Output
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Solution Overview
Problem
Existing oscillator circuits for signal transmitters, particularly those used in electrostatic pens for tablet computers, are limited by the supply voltage, restricting the voltage amplitude of oscillations and requiring high-voltage silicon devices or discrete transformers, which are not cost-efficient or miniaturized.
Innovation Solution
The proposed oscillator circuit employs a resonant circuit with a capacitive coupling mechanism, using a pump capacitor and phase shifting circuit to generate oscillations exceeding the supply voltage without high-voltage silicon devices, allowing for fine-tuning and energy recuperation, thus eliminating the need for on-chip voltage multiplication and discrete transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If switches are used to recharge a resonant capacitor by connecting it in parallel with a voltage supply, then the oscillation can be generated, but the voltage amplitude cannot exceed the supply voltage
Solution Approach 1:
The patent introduces a resonant circuit as an intermediary energy storage system between the voltage supply and the output. The resonant capacitor and inductor work together to store and release energy, enabling voltage amplification through resonance without directly connecting the output to the supply voltage, thus overcoming the limitation where output voltage cannot exceed supply voltage
Solution Approach 2:
The patent employs periodic switching of the resonant circuit at its resonant frequency to build up oscillations. By periodically charging and discharging the resonant capacitor through the inductor at the resonant frequency, energy accumulates in the resonant circuit, generating voltage amplitudes that exceed the supply voltage through the Q-factor of the resonant circuit
2Strength
If discrete transformers or on-chip charge pumps are used to multiply voltage, then high-voltage output can be achieved, but device size and cost increase
Solution Approach 1:
The resonant circuit serves multiple functions simultaneously: it acts as an energy storage element, a voltage amplifier, and an oscillation generator. By using the same resonant capacitor and inductor for both oscillation generation and voltage multiplication, the circuit eliminates the need for separate transformers or charge pumps, reducing device size and component count
Solution Approach 2:
The patent changes the operating parameters by utilizing the resonant frequency of the LC circuit to achieve voltage multiplication. Instead of using traditional voltage multiplication techniques that require additional components, the circuit exploits the natural resonance parameters of the LC combination to amplify voltage, thereby reducing device size while maintaining high-voltage output capability
3Strength
If high-voltage silicon devices or discrete transformers are used, then voltage amplitude can exceed supply voltage, but cost and device complexity increase
Solution Approach 1:
The resonant circuit acts as an intermediary that enables voltage amplification using only low-voltage standard silicon components. The resonant capacitor and inductor together create a high-Q resonance that amplifies the supply voltage to achieve high-voltage output without requiring any high-voltage rated components, thus simplifying manufacturing and reducing cost
Solution Approach 2:
The patent replaces the mechanical/discrete approach of using physical transformers with an integrated electronic resonant circuit implementation. The LC resonant circuit provides the same voltage multiplication function as a transformer but in an integrated, planar format suitable for standard silicon fabrication processes, reducing both cost and manufacturing complexity
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 solution enables the generation of high-voltage sinewave signals with reduced power consumption and energy recuperation, achieving voltage amplitudes beyond the supply voltage while maintaining a cost-efficient and miniaturized design without high-voltage silicon components.
Implementation Method 1
The resonant circuit is operable to resonate at a desired oscillation frequency and is operable to provide an output voltage to be used by the signal transmitter
Implementation Method 2
The driving branch comprises a pump capacitor connected to the resonant circuit
Data Source
Figure 1~2
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Figure 6~8
AI summary
The disclosure concerns an oscillator circuit (10) for a signal transmitter, the oscillator circuit (10) comprising: - a resonant circuit (12) comprising a resonant inductor (LR) and a resonant capacitor (CR) parallel to the resonant inductor (LR) or comprising a crystal device, - a driving branch (14) comprising a pump capacitor (CP) connected to the resonant circuit (12), - a feedback branch (20) connected to the resonant circuit (12), - a phase shifting circuit (22) connected to the resonant circuit (12) via the feedback branch (20), - a comparator circuit (24) connected to the feedback branch (20) via the phase shifting circuit (22) and - a driver circuit (28) connected to an output of the comparator circuit (24) and operable to charge the pump capacitor (CP).