Inverting Amplifier High Input Impedance Negative Feedback Voltage
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Solution Overview
Problem
Conventional voltage regulators face challenges in generating a negative output voltage using a positive input voltage, as existing solutions like level shifters and inverting amplifiers either have limited signal processing range or introduce load on the resistor divider, distorting the feedback signal and output voltage.
Innovation Solution
A novel inverting amplifier with high input impedance, connected to a MOSFET gate, converts negative feedback voltage to a positive feedback voltage of the same absolute magnitude without affecting the resistor divider, allowing for accurate processing and phase inversion, while a versatile controller IC can handle both positive and negative output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional inverting amplifier is used to convert negative feedback voltage to positive feedback voltage, then the feedback voltage can be processed by downstream circuitry, but the low input impedance places a load on the resistor divider which distorts the feedback signal magnitude and output voltage
Solution Approach 1:
The patent introduces an intermediary circuit between the resistor divider and the inverting amplifier. This intermediary buffer circuit has high input impedance that does not load the resistor divider, and its output drives the inverting amplifier. This mediator isolates the resistor divider from the loading effect, preserving feedback signal accuracy while enabling proper processing of negative feedback voltages
Solution Approach 2:
The patent combines multiple circuit elements with different impedance characteristics to create a composite feedback processing system. The high-impedance buffer stage is combined with the inverting amplifier stage, creating a composite structure that provides both high input impedance (to avoid loading) and proper signal inversion functionality
2Adaptability or versatility
If a level shifter is used to convert negative feedback voltage to positive feedback voltage, then the voltage range can be adjusted, but it can only accurately process a narrow range of signals and requires additional circuitry for phase inversion
Solution Approach 1:
The inverting amplifier circuit is designed to perform multiple functions: it inverts the negative feedback voltage to positive, provides the necessary voltage level shifting, and inherently handles the phase inversion requirement. This single multi-functional circuit replaces what would otherwise require separate level shifter and phase inverter circuits, reducing overall system complexity
Solution Approach 2:
The patent merges the level shifting function and the phase inversion function into a single inverting amplifier stage. Instead of using separate circuits for level shifting and phase inversion, the inverting amplifier simultaneously accomplishes both tasks, simplifying the downstream circuitry
Data Source
AI summary
In the example of a voltage regulator outputting a negative voltage, its feedback voltage will also be negative. The feedback voltage is typically created using a resistor divider. A controller IC is powered by only a positive voltage and receives the negative feedback voltage at a high impedance input of an inverting amplifier. Therefore, the inverting amplifier does not load the resistor divider, resulting in an accurate regulated output voltage. The inverting amplifier converts the negative feedback voltage to a positive feedback voltage for further processing by the controller IC. An error amplifier and a power good monitor receive both the original feedback voltage and the inverted feedback voltage and use whichever feedback voltage is the more positive one. Therefore, the controller IC may be used in voltage regulators that generate either negative or positive output voltages.