Adjustable Transformer High Output Power Amplifier
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Solution Overview
Problem
Existing high output power amplifiers face limitations in dynamic range and efficiency due to fixed load resistance and voltage transformation ratios, leading to signal distortion and reduced efficiency when load resistance is adjusted.
Innovation Solution
A high output power amplifier design featuring paired power transistors with differential input signals, capacitors between output leads, and a transformer with adjustable voltage transformation ratio, allowing for on/off operation of power transistors to adjust load resistance without signal distortion, using a Class E operation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If load resistance is adjusted using varactor diodes, then load resistance can be controlled, but output voltage is clamped by turn-on voltage and signal distortion occurs
Solution Approach 1:
The patent introduces an inductor as an intermediary component between the power amplifier output and the load. This inductor acts as a blocking element that prevents the turn-on voltage clamping effect of varactor diodes from reaching the output signal, thereby eliminating signal distortion while still allowing load resistance adjustment through the varactor diodes connected in parallel with the inductor.
2Adaptability or versatility
If switching transistors are used to change load resistance, then load resistance can be changed, but efficiency is reduced due to large transistor size and turn-on resistance
Solution Approach 1:
The patent replaces large, power-consuming switching transistors with small-signal varactor diodes that consume minimal power. The varactor diodes function as voltage-controlled resistors, allowing load resistance adjustment without the significant power losses associated with switching transistor turn-on resistance and large device sizes.
3Power
If source voltage is adjusted using DC-DC converter or LDO, then output power can be controlled, but dynamic range is limited
Solution Approach 1:
The patent implements dynamic load resistance adjustment using voltage-controlled varactor diodes, allowing the amplifier to adapt its output impedance to match different load conditions. This dynamic adaptation extends the dynamic range beyond what fixed source voltage control methods like DC-DC converters or LDOs can achieve, enabling efficient operation across a wider power range.
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
The design enhances dynamic range and efficiency by up to 5 dB and increases efficiency from 10% to 20% at half power, maintaining efficiency without signal distortion by adjusting voltage transformation ratio and load resistance.
Implementation Method 1
a transformer whose primary nodes are connected to the output leads of the amplifiers, respectively, and whose secondary nodes are used as output leads
Data Source
AI summary
A high output power amplifier with change of voltage transformation ratio of a transformer is disclosed. The high output power amplifier using a transformer installed to output leads thereof, which can increase dynamic range and efficiency thereof as voltage transformation ratio of the transformer is adjusted and load resistance is adjusted so as not to generate signal distortion phenomenon and not to decrease its efficiency.