Differential Class E Amplifier Layout for Higher-Frequency Operation
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Solution Overview
Problem
Existing differential power amplifiers face challenges in increasing the operation frequency of Class E operation due to inter-wire parasitic capacitance in magnetically coupled transformers.
Innovation Solution
A differential power amplifier configuration with a Class E amplifier, including transistors, capacitors, and a separate inductor connected between the output nodes and power supply, allowing independent adjustment of circuit parameters to support higher frequency operations, and utilizing a balun transformer with band elimination filter characteristics to reduce noise leakage and parasitic oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetically coupled transformer is used for differential output conversion, then the amplifier can perform Class E operation, but the inter-wire parasitic capacitance of the primary coil limits the operation frequency increase
Solution Approach 1:
The invention separates the choke inductor function from the Class E inductor function. The differential power amplifier uses a dedicated Class E inductor connected between the output nodes to enable Class E operation, while the choke inductor connects the output nodes to the power supply terminal. This segmentation eliminates the harmful inter-wire parasitic capacitance effect that limited frequency increase in previous designs.
Solution Approach 2:
The invention extracts the Class E inductor function from the magnetically coupled transformer's primary coil. By using a separate Class E inductor specifically for Class E operation and a separate choke inductor for power supply connection, the design removes the parasitic capacitance constraint that existed when the primary coil had to serve dual purposes.
2Reliability
If additional band pass filters are added to reduce noise leakage and parasitic oscillations, then the amplifier performance improves, but the device complexity and cost increase
Solution Approach 1:
The balun transformer in the invention is designed to simultaneously perform multiple functions: differential-to-single-ended conversion, band elimination filtering to reduce noise leakage and parasitic oscillations, and impedance transformation. By making the balun transformer multi-functional, the design eliminates the need for separate band pass filters, thereby reducing device complexity and cost while maintaining improved reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables increased operation frequency, reduces noise leakage, and prevents parasitic oscillations, allowing for broader band operation and cost reduction by eliminating the need for additional band pass filters.
Implementation Method 1
at least one choke inductor connecting the two output nodes to the power supply terminal
Implementation Method 2
the two first capacitors and the first inductor are adjusted to satisfy a condition for Class E operation
Implementation Method 3
utilizing a balun transformer with band elimination filter characteristics
Data Source
AI summary
A Class E amplifier is configured to amplify a differential signal. Two output nodes of the Class E amplifier are connected to the power supply terminal with at least one choke inductor interposed therebetween. The Class E amplifier includes two transistors. The two transistors each includes a base or a gate connected to a corresponding one of two input nodes of the Class E amplifier and a collector or a drain connected to a corresponding one of the two output nodes of the Class E amplifier. First capacitors are each connected between the collector or the drain and an emitter or a source of a corresponding one of the two transistors. A first inductor is connected between the collector or the drain of one of the two transistors and the collector or the drain of the other of the two transistors.