Differential Input Circuit for OLED Panel Signal Scaling
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Solution Overview
Problem
The existing OLED pixel circuits face challenges in transforming analog sensing signals from OLED panels into a low-voltage range suitable for analog-to-digital converters, as the signal range exceeds the operating voltage of these converters, necessitating a technique to downscale and improve signal quality.
Innovation Solution
A differential input circuit with a sampling and scaling circuit is introduced, which converts single-end analog voltage signals into pairs of differential input signals for a gain amplifier, utilizing multiple paths to sample and scale the signals with shift voltages, ensuring the output range is compatible with the ADC's input range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the analog sensing signal range is kept as is, then the full sensing range is maintained, but the signal is incompatible with the ADC input voltage range
Solution Approach 1:
The patent applies parameter changes by transforming the analog sensing signal through voltage scaling and shifting operations. The signal undergoes linear transformation where the voltage range is scaled down and shifted to match the ADC's input voltage range, converting an incompatible high-voltage signal into a compatible low-voltage signal while preserving the sensing information.
Solution Approach 2:
The patent introduces an intermediary circuit (the transformation circuit comprising scaling and shifting components) that mediates between the sensing signal source and the ADC. This intermediary circuit performs the voltage range adaptation, acting as a bridge that converts the signal from one voltage domain to another without losing the essential sensing data.
2Adaptability or versatility
If a transformation circuit is added to downscale the signal, then ADC compatibility is achieved, but the circuit complexity increases
Solution Approach 1:
The patent segments the signal transformation function into distinct operational stages: voltage scaling and voltage shifting. This is achieved through separate circuit components that perform each function independently, allowing for modular design and easier implementation while achieving the overall goal of ADC compatibility.
3Measurement precision
If single-end analog signals are used, then the circuit is simple, but the signal quality is insufficient for accurate degradation detection
Solution Approach 1:
The patent inverts the signal approach by converting the single-end analog sensing signal into a differential signal format. Instead of processing the single-ended signal directly, the circuit generates complementary signals that differ in phase or polarity, which when processed differentially, reject common-mode noise and enhance the measurement precision for degradation detection.
Data Source
AI summary
A differential input circuit and a driving circuit including the same are provided. The differential input circuit transforms an analog voltage signal corresponding to a sensing line on an OLED panel to a pair of differential input signals being output to a gain amplifier. The differential input circuit includes a sampling circuit and a scaling circuit. The sampling circuit receives the analog voltage signal and a reference voltage through a first scaling path and a second scaling path, respectively. The scaling circuit includes a first scaling path and a second scaling path. The first scaling path and the second scaling path collectively generate the pair of differential input signals, based on a first shift voltage, a first scaled voltage, a second shift voltage, and a second scaled voltage. The first shift voltage is less than the second shift voltage.