Oscillator Circuit Stabilization for Display Modules
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Solution Overview
Problem
The existing polysilicon liquid crystal display modules face challenges in stabilizing oscillation frequency due to manufacture variations and supply voltage fluctuations in thin film transistors, leading to increased costs and development time.
Innovation Solution
Incorporating a modified oscillator circuit with (2n+1) CMOS inverters connected in series, an integrator circuit with a resistor and capacitor, and specific transistor configurations to reduce the impact of transistor variations and supply voltage on oscillation frequency, stabilizing the oscillation frequency by controlling voltage transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ring oscillator circuit with CMOS inverters is used, then oscillation frequency can be generated, but the oscillation frequency varies due to manufacture variation of thin film transistors
Solution Approach 1:
The patent introduces a feedback mechanism where the output of the (2n+1)-th inverter is fed back to the input of the first inverter through an integrator circuit. This feedback loop compensates for frequency variations by adjusting the input signal based on the actual oscillation output, thereby stabilizing the oscillation frequency despite transistor manufacturing variations.
Solution Approach 2:
The patent changes the operating parameters of the oscillator circuit by using (2n+1) inverters instead of a traditional ring oscillator configuration, and introduces an integrator circuit that modifies the feedback signal. This parameter change transforms the circuit's frequency characteristics, making it less sensitive to transistor variations.
2Reliability
If a ring oscillator circuit with CMOS inverters is used, then oscillation frequency can be generated, but the circuit is largely affected by supply voltage variations
Solution Approach 1:
The feedback mechanism through the integrator circuit compensates for supply voltage variations. The integrator accumulates errors caused by voltage fluctuations and adjusts the input signal accordingly, maintaining stable oscillation frequency despite power supply changes.
Solution Approach 2:
The integrator circuit acts as a cushioning element that anticipates and compensates for supply voltage variations before they significantly affect the oscillation frequency. By integrating the feedback signal, it smooths out voltage fluctuations and their impact on the oscillator.
3Ease of manufacture
If driver circuits are integrated with liquid crystal display panel, then costs and development time increase when dedicated drivers are required
Solution Approach 1:
The patent creates a universal oscillator circuit configuration that can be integrated into display panels without requiring dedicated external drivers. The (2n+1) inverter-based oscillator with integrator feedback is designed to be self-contained and adaptable, reducing the need for additional specialized components while maintaining functionality.
Data Source
AI summary
An oscillator circuit includes (2n+1) inverters connected in series when n is a natural number, an integrator circuit having an input terminal connected to an output terminal of a (2n+1)-th inverter and an output terminal connected to an input terminal of a first inverter, first and second p-type transistors connected in series between the input terminal of the first inverter and a first reference potential, and first and second n-type transistors connected in series between the input terminal of the first inverter and a second reference potential. An output voltage of a j-th inverter is applied to control electrodes of the first p-type transistor and the first n-type transistor. An output voltage of a k-th inverter is applied to control-electrodes of the second p-type transistor and the second n-type transistor. Symbol j is an odd number, k is an even number, and j<k=2n is satisfied.