High-Frequency Amplifier Circuit With Phase-Matched Transistor Coupling
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Solution Overview
Problem
Current high frequency amplifier circuits do not effectively increase output electrical power despite enlarging input electrical power due to voltage suppression in the second transistor, which limits the amplitude of the high frequency signal.
Innovation Solution
The circuit design includes a distributed constant line between the resistor and the source of the second transistor, allowing the source to be coupled to the drain of the first transistor for high frequency waves, and the resistor determines the potential of the gate and source of the second transistor, while the distributed constant lines match impedance between the transistors, and the resistor matches resistance, adjusting the phase difference between the drain and source voltages of the second transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the input electrical power is enlarged to increase output power, then the output electrical power can be increased, but the voltage suppression in the second transistor limits the amplitude of the high frequency signal and prevents effective power increase
Solution Approach 1:
A distributed constant line (impedance transformation line) is introduced as an intermediary element between the resistor and the source of the second transistor. This line transforms the impedance to ensure that the source of the second transistor is properly coupled to the drain of the first transistor for high frequency waves, while the resistor determines the potential of the gate and source. This intermediary structure resolves the voltage suppression issue by optimizing the impedance matching and signal amplitude at the second transistor's source terminal.
Solution Approach 2:
The patent adjusts the phase difference between the drain and source voltages of the second transistor by modifying the circuit configuration. Specifically, the distributed constant line and resistor arrangement changes the voltage parameters to achieve an optimal phase difference (approximately 180 degrees), which enhances the drain-source voltage and enables effective power amplification without voltage suppression limitations.
2Illumination intensity
If the amplitude of the high frequency signal is increased to improve output power, then the output power can be increased, but the voltage suppression in the second transistor prevents amplitude increase
Solution Approach 1:
The distributed constant line serves as an intermediary that couples the source of the second transistor to the drain of the first transistor for high frequency waves. This impedance transformation structure allows the high frequency signal to maintain its amplitude by proper impedance matching, preventing the voltage suppression that would otherwise limit signal amplitude in the second transistor.
Solution Approach 2:
By changing the phase relationship between drain and source voltages through the modified circuit configuration, the patent enables the high frequency signal to achieve larger amplitude. The optimal phase difference (approximately 180 degrees) between drain and source voltages of the second transistor constructive enhances the signal amplitude, overcoming the voltage suppression limitation.
3Device complexity
If the circuit configuration is simplified to reduce complexity, then the device complexity is reduced, but the impedance matching and phase control between transistors cannot be optimized
Solution Approach 1:
The patent applies local quality by making the source of the second transistor have different coupling characteristics for different frequency components. For direct current, the source is connected through the resistor to ground, while for high frequency waves, the distributed constant line couples the source to the drain of the first transistor. This localized differentiation in coupling quality enables both impedance matching for power optimization and manageable circuit complexity.
Data Source
AI summary
A high frequency amplifier circuit includes a first transistor that has a first terminal, a second terminal and a control terminal, the first terminal being grounded, a second transistor that has a first terminal, a second terminal and a control terminal, the control terminal of the second transistor being coupled to the second terminal of the first transistor, the first terminal of the second transistor being coupled to only the second terminal of the first transistor with respect to high frequency wave, the second terminal of the second transistor being coupled to a direct-current power supply, and a first resistor of which first terminal is coupled to a node between the second terminal of the first transistor and the control terminal of the second transistor, and of which second terminal is coupled to the first terminal of the second transistor.