Differential Power Amplifier Layout for Oscillation Control
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Solution Overview
Problem
Power amplifiers with differential structures face challenges in reducing transistor size to prevent oscillation, which increases driving power requirements and manufacturing costs.
Innovation Solution
A power amplifier design that includes a switch transistor connected only to the assistant transistors causing oscillation, with a configuration of transistors and inductors that allow the switch transistor to be smaller in size, reducing the risk of oscillation and lowering driving power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch transistor is used to control oscillation of assistant transistors, then oscillation can be prevented, but the switch transistor size must be very big to bear all currents
Solution Approach 1:
The patent divides the current control function into two separate switch transistors: one switch transistor connects the first assistant transistor to ground, and another switch transistor connects the second assistant transistor to ground. This segmentation allows each switch transistor to handle only a portion of the total current, reducing the size requirement for each individual transistor while maintaining effective oscillation control.
2Power
If assistant transistors are used to assist amplification, then output power increases and driving power decreases, but oscillation is generated when no signal is applied
Solution Approach 1:
The patent applies preliminary action by using switch transistors to proactively control the assistant transistors' operation states. The switch transistors are configured to automatically connect the assistant transistors to ground when oscillation occurs (no signal input), preventing oscillation before it affects system performance. During normal operation, the switch transistors disconnect to allow the assistant transistors to provide amplification assistance.
3Ease of manufacture
If the switch transistor size is reduced, then manufacturing costs decrease, but the ability to prevent oscillation is compromised
Solution Approach 1:
The patent segments the current handling responsibility across multiple smaller switch transistors rather than using one large transistor. This segmentation enables the use of smaller, less expensive transistors that are easier to manufacture, while collectively maintaining the full current handling capability needed for effective oscillation prevention.
Data Source
AI summary
Provided is a power amplifier which includes: a first transistor and a second transistor each having a first end connected to a first power source supplying a first voltage and to which signals having a same size but opposite polarities are input; a third transistor and a fourth transistor having first ends respectively connected to the first ends of the first transistor and the second transistor; and a fifth transistor having a first end connected to second ends of the third and fourth transistors and controlling oscillation of the third or fourth transistor.