RF Power Amplifier LC Ground Path for Harmonic Suppression
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Solution Overview
Problem
Harmonic components generated by heterojunction bipolar transistor (HBT) devices in radio-frequency modules are coupled to the output signal path through the ground of a silicon device, leading to degradation of distortion characteristics.
Innovation Solution
A radio-frequency circuit with an LC circuit connected to the power supply path of the amplifier circuit, grounded through a switch circuit, which includes a first capacitor and an inductor in series, is used to suppress harmonic component coupling by attenuating noise components in the second mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HBT device and switch circuit are integrated in the same silicon device, then device integration is improved, but harmonic components are coupled to output signal path through ground, degrading distortion characteristics
Solution Approach 1:
An LC circuit is introduced as an intermediary component between the power supply path and ground. This LC circuit acts as a filter that blocks harmonic components from coupling through the ground path to the output signal path, while allowing the power supply path to function normally. The intermediary LC circuit resolves the contradiction by preventing harmful coupling without separating the HBT device and switch circuit.
Solution Approach 2:
The impedance characteristics of the power supply path are changed by introducing the LC circuit with specific inductance and capacitance values. The LC circuit is designed to present high impedance to harmonic frequency components at the operating frequency, thereby blocking the coupling path for harmonics while maintaining proper power supply function. This parameter change resolves the harmonic coupling issue while preserving device integration.
2Device complexity
If ground path is used for switch circuit, then circuit simplicity is improved, but noise components from amplifier circuit propagate through LC circuit to output signal path
Solution Approach 1:
The LC circuit serves as a mediating element in the ground path that selectively blocks noise components while allowing the ground connection to function. By positioning the LC circuit as an intermediary between the amplifier circuit ground and the output signal path ground, noise propagation is prevented without eliminating the ground path connection, thus maintaining circuit simplicity while reducing harmful noise coupling.
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 configuration effectively suppresses degradation of distortion characteristics by attenuating harmonic components propagating through the output signal path, improving signal quality.
Implementation Method 1
an LC circuit that is connected, at its first end, to a power supply path of the amplifier circuit and that is grounded, at its second end, through a switch circuit. The LC circuit includes a first capacitor and an inductor that is connected in series to the first capacitor
Data Source
AI summary
A power amplifier circuit and an LC circuit are included. The power amplifier circuit amplifies a radio frequency signal by switching between the first mode, in which power is amplified by using the envelope tracking system, and the second mode, in which power is amplified by using the average power tracking system. The LC circuit is connected, at its first end, to the power supply path of the power amplifier circuit and that is grounded, at its second end, through a switch circuit. The LC circuit includes a first capacitor and an inductor that is connected in series to the first capacitor. The switch circuit is controlled to be switched off in the first mode and is controlled to be switched on in the second mode.