Shared-Resistor Variable Gain Amplifier for Smaller IC Area
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Solution Overview
Problem
Conventional variable gain amplifier circuits require a large number of circuit elements, leading to increased area requirements in semiconductor integrated circuits due to the need for multiple resistors and transistors for amplification and output circuits.
Innovation Solution
A variable gain amplifier circuit design that reduces the number of resistors needed for amplification by using a common signal input for multiple differential circuits and a shared output circuit with fewer resistors, allowing for reduced area usage in semiconductor integrated circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate non-inverting amplifiers are used to achieve variable gain, then signal amplification capability is improved, but the number of circuit elements increases
Solution Approach 1:
The patent combines multiple amplifier functions into a single differential amplifier circuit by using a shared output circuit and selectively connecting different resistor pairs to the inverting input terminal. Instead of having separate amplifiers for each gain setting, the invention merges them into one circuit that can be configured for different gains by selecting which resistor pair is connected, thereby reducing the total number of circuit elements while maintaining variable gain capability.
Solution Approach 2:
The single differential amplifier circuit is designed to perform multiple amplifier functions with different gain settings. The shared output circuit and the ability to selectively connect different resistor pairs (R1-R2, R3-R4, R5-R6) allow one circuit to provide multiple gain settings (6dB, 4dB, 2dB, 0dB), making the circuit universal and eliminating the need for separate dedicated amplifiers for each gain level.
2Manufacturing precision
If multiple resistors are used for each non-inverting amplifier configuration, then amplification precision is improved, but the area required in semiconductor integrated circuit increases
Solution Approach 1:
The patent merges the resistor networks of multiple amplifiers into a single shared resistor network. Instead of having separate resistors for each amplifier, the invention uses one set of resistors (R1-R6) that can be selectively connected to provide different gain settings. This sharing of resistor elements significantly reduces the total area required in the semiconductor integrated circuit while maintaining the precision needed for different amplification levels.
Solution Approach 2:
The circuit employs dynamic switching of resistor connections based on the desired gain setting. By using switches to selectively connect different resistor pairs to the inverting input terminal, the circuit can dynamically reconfigure its resistance network to achieve different gain precision levels without requiring physically separate resistor sets for each configuration, thereby reducing overall component area.
Data Source
AI summary
A variable gain amplifier circuit capable of eliminating circuit elements and the area for circuits when formed into an integrated circuit is disclosed. The circuit includes plural differential circuits, one of the input terminals of each of the differential circuits being connected in common to a signal input terminal, any one of the differential circuits being selected to operate; an output circuit having an input terminal connected in common to each output terminal of the differential circuits, the output circuit inputting an output signal of any of differential circuits and outputting an output signal from the signal output terminal; and plural resistors connected in series between the signal output terminal and a reference voltage terminal, in which each of junctions between the resistors is connected to one of the other input terminals of the differential circuits.