Harmonic-Terminated Amplifier Output Network for Low-Band Efficiency
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Solution Overview
Problem
Conventional power amplifiers face efficiency reduction and signal loss due to harmonic interference, particularly in inverse class F amplifiers with center frequencies below 2.6 GHz, where large inductors are impractical for manufacturing.
Innovation Solution
Implementing a T network output impedance structure with harmonic termination circuits configured to resonate at second and third harmonics, using bond wires and capacitors, to enhance efficiency and reduce signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional power amplifiers use traditional output impedance networks, then the amplifier can operate at center frequencies below 2.6 GHz, but large inductors are required which are impractical for manufacturing
Solution Approach 1:
The patent segments the output impedance network into a T-network configuration with separate inductors (L1, L2) and capacitors (C1, C2, C3) that can be independently optimized and manufactured. This segmentation allows each component to be smaller and more practical while collectively achieving the required impedance transformation function that previously required a single large inductor.
Solution Approach 2:
The patent changes the electrical parameters of the network by introducing multiple capacitors with specific values (C1, C2, C3) in conjunction with the inductors to create a T-network that transforms the output impedance to match the load impedance. This parameter transformation allows the use of smaller, more manufacturable components while achieving the same electrical function.
2Use of energy by moving object
If harmonic frequencies are not terminated, then the amplifier structure remains simple, but efficiency is reduced and signal loss increases
Solution Approach 1:
The patent converts the harmful effect of harmonic frequencies by using harmonic termination circuits that resonate at specific harmonic frequencies (2nd, 3rd, etc.) to present high impedance paths that short-circuit the harmonics to ground. This transforms the harmful harmonic content into a beneficial filtering function that improves efficiency while maintaining reasonable circuit complexity through targeted harmonic suppression.
Solution Approach 2:
The output impedance network serves multiple functions simultaneously: it transforms the output impedance to match the load, filters harmonic frequencies through resonant circuits, and provides a structured platform for adding multiple harmonic termination circuits. This multi-functionality improves efficiency without proportionally increasing complexity.
3Loss of energy
If the Q-factor is increased to reduce signal attenuation, then signal loss is reduced, but the bandwidth may be narrowed
Solution Approach 1:
The patent employs dynamic Q-factor management by using the T-network configuration with multiple reactive components that can be optimized to provide high Q-factor at the fundamental frequency to reduce signal attenuation, while the distributed capacitance and inductance values are selected to maintain adequate bandwidth for the operating range. The network dynamically adapts the impedance transformation ratio across the frequency 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 T network configuration improves manufacturability and efficiency by reducing signal attenuation and increasing the Q-factor, while effectively terminating harmonics, thus enhancing amplifier performance.
Implementation Method 1
The second harmonic termination circuit may be configured to have a resonance corresponding to a second harmonic of a center frequency of the amplifier device
Implementation Method 2
The third harmonic termination circuit may be configured to have a resonance corresponding to a third harmonic of the center frequency of the amplifier device
Data Source
AI summary
An amplifier device may include an amplifier transistor and having harmonic termination circuitry and an output impedance network, such as an output T network, coupled to the output of the amplifier transistor. The amplifier device may be configured as an inverted F class amplifier having an operational frequency range with a center frequency of less than or equal to around 2.6 GHz. The harmonic termination circuitry and output impedance network may be configured to create a short circuit or near short circuit at the amplifier transistor output for third harmonic frequencies of the center frequency of the amplifier transistor and to create an open circuit or near open circuit at the amplifier transistor output for second harmonic frequencies of the center frequency. The output impedance network may be configured to increase the output impedance at the center frequency and reduce signal loss for the amplifier device.