Resonant Oscillator Amplitude Control Beyond Supply Voltage
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Solution Overview
Problem
Existing oscillator circuits for electrostatic pens in tablet computers face limitations in output voltage amplitude, requiring high-voltage components and inefficient power management, and lack mechanisms for regulating output signal amplitude variations due to load and component aging.
Innovation Solution
A new oscillator circuit design incorporating a resonant circuit with capacitive coupling, a phase extraction circuit, and an amplitude regulation loop, utilizing low-voltage silicon devices to generate a sinewave signal exceeding supply voltage without high-voltage components, and featuring energy recuperation and power-efficient operation.
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 transformer as an intermediary component between the voltage supply and the resonant capacitor. The transformer enables voltage multiplication, allowing the resonant capacitor to be recharged at a voltage level higher than the supply voltage. This resolves the contradiction by mediating the voltage transfer process through electromagnetic induction, where the primary winding receives supply voltage and the secondary winding delivers multiplied voltage to the resonant capacitor.
Solution Approach 2:
The patent changes the voltage parameter through transformer turns ratio. By selecting appropriate primary and secondary winding turns, the output voltage can be multiplied to exceed the supply voltage. This parameter transformation allows the oscillation voltage amplitude to surpass the supply voltage limitation while maintaining proper operational control.
2Strength
If discrete transformers or on-chip charge pumps are used to multiply voltage, then the voltage amplitude can exceed supply voltage, but the device complexity and component count increase
Solution Approach 1:
The patent merges the transformer with the resonant circuit by making the resonant inductor the transformer's inductor. This integration eliminates the need for separate discrete transformers or on-chip charge pumps, reducing component count while achieving voltage multiplication. The resonant circuit and voltage multiplication function are combined into a unified structure.
Solution Approach 2:
The transformer in the patent serves multiple functions simultaneously: it acts as both the voltage multiplication device and the resonant inductor. This multi-functionality reduces the overall device complexity by eliminating redundant components while maintaining the ability to generate high voltage amplitude oscillations.
3Strength
If current supplies are used to build up oscillation, then the oscillation can be generated, but the voltage amplitude cannot exceed the supply voltage due to polarity limitations
Solution Approach 1:
The transformer acts as an intermediary that overcomes the polarity constraints of current supplies. By using electromagnetic induction, the transformer can transfer energy to the resonant capacitor regardless of the current supply's polarity limitations, enabling voltage multiplication while maintaining adaptability to different operating conditions.
4Strength
If high-voltage components are used to achieve high voltage amplitude, then the voltage requirement is met, but the power consumption increases and miniaturization is hindered
Solution Approach 1:
The patent combines the resonant circuit with the voltage multiplication function, eliminating the need for separate high-voltage components. This integration reduces power consumption by minimizing energy losses associated with discrete high-voltage components while achieving the required voltage amplitude through the unified resonant transformer structure.
Solution Approach 2:
The patent uses periodic charging of the resonant capacitor through the transformer to build up voltage amplitude. This periodic energy transfer is more efficient than continuous high-voltage generation, reducing overall power consumption while achieving the necessary voltage levels for electrostatic pen operation.
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 design achieves stable high-voltage sinewave generation with efficient power consumption and adaptive amplitude control, overcoming limitations of prior art by eliminating the need for high-voltage components and transformers.
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
AI summary
An oscillator circuit for a signal transmitter, the oscillator circuit including: a resonant circuit (12) including a resonant inductor (LR) and a resonant capacitor (CR) parallel to the resonant inductor (LR); a driving branch (14) including a pump driver bank (38) connected to the resonant circuit (12); a feedback branch (15) connected to the resonant circuit (12), and an amplitude regulation loop (28) connected to the resonant circuit (12) via the feedback branch (15) and operable to control the pump driver bank (38). The amplitude regulation loop (28) includes: an envelope detector (30) connected to the resonant circuit (12) via the feedback branch (15), a differential amplifier (32) connected to the feedback branch (15) via the envelope detector (30), and an analog to digital converter (ADC) (34) connected to an output of the differential amplifier (32) and operable to control the pump driver bank (38).