High-Impedance Level-Shifting Amplifier for Over-Supply Input Signals
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Solution Overview
Problem
Prior art level-shifting amplifiers often exhibit low input impedance and require significant bias current, limiting their effectiveness in handling input signals that exceed the supply voltage range.
Innovation Solution
The development of level-shifting amplifier circuits with high input impedance, exceeding 100 MOhms, which do not require significant bias current, utilizing configurations such as JFET-based and MOSFET-based designs with specific transistor architectures and current mirrors to achieve high input impedance and improved linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional level-shifting amplifier circuits are used, then the circuit can handle input signals beyond supply voltage, but the input impedance is low and significant bias current is required
Solution Approach 1:
The patent changes the operating parameters of the amplifier by using JFET and MOSFET devices with specific characteristics (high input impedance, low bias current requirements) to achieve both extended input signal range and reduced bias current consumption simultaneously
Solution Approach 2:
The patent introduces high-impedance buffer stages using JFET/MOSFET devices as intermediaries between the input signal source and the main amplification stage, allowing the circuit to handle signals beyond supply voltage without requiring significant bias current
2Adaptability or versatility
If conventional level-shifting amplifier circuits are used, then the circuit can handle input signals beyond supply voltage, but the input impedance is low
Solution Approach 1:
The patent changes the device type from conventional bipolar transistors to JFET and MOSFET devices, which inherently provide high input impedance characteristics while maintaining the ability to handle input signals beyond the supply voltage range
Solution Approach 2:
The patent adds a high-impedance buffer dimension to the amplifier architecture, creating a two-stage configuration where the first stage provides high input impedance and the second stage provides amplification, thereby achieving both high input impedance and extended signal range
Data Source
AI summary
A level-shifting amplifier is provided for level-shifting an input signal with a voltage magnitude that exceeds a supply voltage of the amplifier. In operation, the amplifier has an input impedance of greater than 100 MOhms.