Integrated Transconductor Biasing for Process-Invariant Gain
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Solution Overview
Problem
Conventional integrated circuits face challenges in maintaining constant transconductance due to resistor variation within the circuit, which requires external components and complex design compensations, increasing costs and power requirements.
Innovation Solution
An integrated amplifier design that achieves substantially constant transconductance by using internal resistors with carefully configured bias currents, making the transconductance independent of resistor process variation and operating conditions, eliminating the need for external components and trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external resistors are used to achieve constant transconductance, then transconductance stability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the resistor from the external environment and integrates it internally within the operational amplifier circuit. By incorporating the resistor as an internal component rather than relying on external components, the circuit achieves transconductance stability while reducing overall device complexity and eliminating the need for external connections.
Solution Approach 2:
The patent merges the function of the resistor with the internal structure of the operational amplifier. The resistor is combined with the bias current generation circuitry within the same integrated circuit, creating a unified structure that provides both the necessary resistance and the bias current to maintain constant transconductance without requiring separate external components.
2Measurement precision
If external resistors and trimming processes are used to compensate for resistor variation, then transconductance precision is improved, but manufacturing cost and processing complexity increase
Solution Approach 1:
The patent implements a self-service mechanism where the circuit automatically compensates for resistor variations through its internal bias current generation system. The circuit monitors and adjusts its own operating parameters using the integrated resistor and bias current sources, eliminating the need for external trimming processes and complex manufacturing compensation techniques.
Solution Approach 2:
The patent changes the operating parameters of the transistors by adjusting the bias current in response to resistor variations. By dynamically modifying the bias current parameter based on the actual resistor value, the circuit maintains constant transconductance precision without requiring physical trimming or manual adjustment during manufacturing.
3Device complexity
If conventional biasing methods are used, then circuit simplicity is maintained, but transconductance varies with resistor process variation
Solution Approach 1:
The patent implements a feedback mechanism where the bias current is generated based on the voltage across the internal resistor. The circuit continuously monitors the resistor value and adjusts the bias current accordingly, creating a closed-loop system that automatically compensates for resistor process variations and maintains stable transconductance while keeping the circuit structure relatively simple.
Solution Approach 2:
The patent creates a composite functional structure by combining the resistor with the bias current generation circuitry within the operational amplifier. This composite structure integrates multiple functions (resistance, current generation, and transconductance control) into a unified system that achieves transconductance stability without significantly increasing circuit complexity.
4Reliability
If resistor trimming is performed during manufacture, then transconductance constant performance is improved, but processing time and manufacturing cost increase
Solution Approach 1:
The patent performs preliminary action by pre-configuring the bias current generation circuitry to work with the internal resistor during the standard manufacturing process. The circuit is designed to automatically compensate for resistor variations through its inherent feedback mechanism, eliminating the need for post-manufacturing trimming operations and reducing total processing time.
Solution Approach 2:
The circuit performs self-adjustment during normal operation rather than requiring external trimming during manufacturing. The automatic feedback mechanism continuously optimizes the transconductance performance based on the actual resistor value, eliminating the need for time-consuming manual or automated trimming processes during the manufacturing stage.
Data Source
AI summary
In one aspect, a resistor process invariant transconductor is provided. The transconductor comprises a voltage input configured to receive at least one voltage signal, a current output configured to provide at least one current signal, wherein a ratio between the at least one voltage signal and the least one current signal forms a total transconductance for the transconductor, and a circuit including at least one integrated resistor connected between the voltage input and the current output, the circuit adapted to maintain the total transconductance substantially constant across variation of the at least one integrated resistor.