Printed Thin-Film Pulse Generator for Stable Monostable Timing
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Solution Overview
Problem
The challenge lies in developing pulse generator circuits using printed thin-film devices, particularly with organic thin-film (OTF) materials, where conventional designs face issues due to low yield, high variability, and instability, making it difficult to fabricate reliable monostable multivibrators with desired pulse widths and requiring minimal thin-film transistors of a single polarity.
Innovation Solution
A pulse generator circuit design comprising thin-film transistors of a single polarity organic semiconductor material, including a capacitor and transistors configured as diodes and resistors, optimized for solution-based printed processes, allowing for the generation of pulses above a voltage threshold for a minimum time interval, suitable for applications like clocking flip-flops and reset signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional monostable multivibrator circuits are implemented using printed organic thin-film processes, then circuit functionality is achieved, but reliability and stability deteriorate due to low yield and high variability
Solution Approach 1:
The circuit design changes the operating parameters by using transistors of a single polarity with specific width-to-length ratios. The first transistor has a larger W/L ratio to function as a diode, while the second has a smaller W/L ratio to function as a resistor, enabling reliable operation despite process variability
Solution Approach 2:
The patent applies different functional configurations to different transistors in the circuit. The first transistor is configured as a diode with its gate connected to its drain, while the second transistor is configured as a resistor with its gate connected to a specific voltage level, creating local functional differences that improve overall circuit reliability
2Ease of manufacture
If conventional monostable multivibrator circuits are implemented using printed organic thin-film processes, then circuit functionality is achieved, but manufacturing precision deteriorates due to high device variability
Solution Approach 1:
The design specifies particular W/L ratios for the transistors to compensate for process variability. By carefully selecting the width-to-length ratios, the circuit achieves consistent pulse width output despite variations in absolute transistor dimensions that are inherent to printed organic thin-film processes
Solution Approach 2:
The circuit function is segmented into distinct transistor roles (diode and resistor functions) with optimized dimensions for each role, allowing the overall circuit performance to be more tolerant of individual device variations
3Reliability
If both N-channel and P-channel devices are formed in OTF processes, then device performance improves, but process complexity and yield worsen
Solution Approach 1:
The circuit achieves universal functionality using only transistors of a single polarity. By configuring transistors to perform multiple functions (switching, diode rectification, and resistance), the design eliminates the need for complementary device pairs while maintaining circuit operation
Solution Approach 2:
The patent extracts and removes the P-channel devices from the conventional monostable multivibrator design, creating a simplified circuit that uses only N-channel (or only P-channel) devices, thereby reducing process complexity and improving yield
4Ease of manufacture
If process-based limits on device size are applied, then fabrication is simplified, but pulse width control capability deteriorates
Solution Approach 1:
The patent changes the controlling parameter from absolute device dimensions to the ratio of dimensions (W/L ratio). This allows pulse width to be controlled by the relative proportions of transistor dimensions rather than absolute sizes, enabling precise control even when device sizes are constrained by process limits
Solution Approach 2:
The design transitions from controlling pulse width through absolute dimension scaling to controlling it through dimensional ratios. This dimensional approach allows independent optimization of fabrication simplicity and pulse width control precision
Data Source
AI summary
A pulse generator circuit is disclosed that is optimized for printed, solution-processed thin film transistor processing. In certain embodiments, the circuit comprises dual thin film transistors that operate as a diode and resistor, respectively. Optionally, a third thin film transistor may be provided to operate as a pass transistor in response to an enable signal. The elements of the circuit are configured such that a rising pulse on an input node triggers an output pulse on an output node in the manner of a monostable multivibrator.