Current-Mirror Bias Circuit for Stable Amplifier Bias Signals
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Solution Overview
Problem
Existing bias circuits face instability due to uncontrollable variations in manufacturing processes and reference voltage levels, affecting the stability of generated bias signals.
Innovation Solution
A bias circuit comprising a current mirror circuit, operational amplifier, and bias generation circuit, where the current mirror circuit generates a reference current and mirrored current, and the operational amplifier adjusts voltages to ensure equal levels, stabilizing the bias signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage source is used to provide a reference voltage, then the bias circuit can generate a bias signal according to the reference voltage, but the level of the reference voltage may vary due to manufacturing process variations, affecting stability of the bias signal
Solution Approach 1:
The patent uses current mirror circuits to create copies of reference currents. The current mirror circuit includes a reference branch that generates a reference current and mirror branches that generate mirrored currents as copies. This copying mechanism allows the circuit to maintain consistent current levels across different branches despite variations in reference voltage, thereby improving bias signal stability while being tolerant to manufacturing variations.
2Reliability
If a current mirror circuit is used to generate reference current and mirrored current, then the bias signal stability is improved, but the device complexity increases due to additional operational amplifier and voltage adjustment mechanisms
Solution Approach 1:
The patent employs operational amplifiers configured as voltage followers with feedback mechanisms. The operational amplifier receives voltages from different branches and generates control voltages that adjust the voltages to equal levels through feedback. This feedback approach automatically maintains voltage equality without requiring complex manual adjustment mechanisms, thus improving bias signal stability while keeping the circuit relatively simple.
3Reliability
If operational amplifier is used to adjust voltages to equal levels, then the impact of voltage variations is reduced, but the device complexity and power consumption increase
Solution Approach 1:
The patent uses operational amplifiers to maintain equipotential conditions between different branches of the current mirror circuit. By generating control voltages that adjust branch voltages to equal levels, the circuit ensures that all critical nodes operate at matched potential levels. This equipotential approach minimizes the impact of voltage variations and reduces unnecessary power consumption by preventing voltage mismatches that would otherwise require additional power to correct.
Data Source
AI summary
A bias circuit includes a current mirror circuit, an operational amplifier, and a bias generating circuit. The current mirror circuit includes a reference branch circuit and at least one mirror branch circuit. The reference branch circuit generates a reference current according to a base current, and the at least one mirror branch circuit generates at least one mirrored current according to the reference current. The operational amplifier receives a first voltage from the reference branch circuit and a second voltage from the at least one mirror branch circuit, and adjusts the first voltage by generating a control voltage according to the second voltage. The bias generating circuit is coupled to the at least one mirror branch circuit and generates a bias signal according to the at least one mirrored current.