Cross-Coupled Power Amplifier Circuit for Stepped Gain Smoothing
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Solution Overview
Problem
In power amplifier circuits for wireless communication, especially in high-frequency bands like 5G, the envelope tracking system struggles to smoothly control the power-supply voltage, leading to discrete gain levels and reduced amplification efficiency due to high power-supply voltage dependence.
Innovation Solution
A power amplifier circuit design incorporating transistors with collector-base capacitance and cross-coupling capacitance circuits to reduce power-supply voltage dependence, enabling continuous amplification by compensating for voltage changes and minimizing gain variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If digital control is used for envelope tracking in high-frequency bands, then power efficiency is improved, but the power-supply voltage cannot track the envelope signal smoothly due to discrete voltage levels
Solution Approach 1:
The patent implements feedback by connecting the collector of each transistor to the base of the other through capacitance circuits. This feedback mechanism compensates for gain variations caused by discrete power-supply voltage changes, allowing the circuit to maintain smooth analog-like amplification characteristics even when operating with digitally controlled discrete voltage levels.
2Extent of automation
If stepped power-supply voltage is used in envelope tracking, then digital control is enabled, but the gain of the power amplifier circuit changes in a stepped manner causing discrete gain levels
Solution Approach 1:
The feedback connection through capacitance circuits between collector and base allows the circuit to automatically compensate for stepped gain variations. The feedback mechanism adjusts the operating point dynamically, transforming discrete voltage steps into smooth continuous amplification output.
Solution Approach 2:
The patent changes the operating parameters of the transistors by utilizing their nonlinear characteristics and the feedback network to convert discrete voltage steps into continuous gain control, effectively transforming the stepped nature of digital control into smooth analog-like amplification.
3Speed
If high modulation bandwidth is used in 5G, then signal speed increases, but the envelope tracker cannot reach the signal speed causing tracking failure
Solution Approach 1:
The feedback mechanism provides rapid response to envelope signal changes, enabling the power amplifier to track high-speed modulated signals in 5G bands. The feedback loop compensates for the limited bandwidth of the envelope tracker, effectively extending the tracking capability to match high signal speeds.
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 achieves reduced power-supply voltage dependence, allowing for efficient power amplification with digital envelope tracking, preventing harmonic components from modulating into the high-frequency signal and enhancing linearity.
Implementation Method 1
a first capacitance circuit electrically connected between the collector of the second transistor and the base of the first transistor; and a second capacitance circuit electrically connected between the collector of the first transistor and the base of the second transistor
Data Source
AI summary
A power amplifier circuit includes a first transistor having an emitter electrically connected to a common potential, a base to which a first high-frequency signal is input, and a collector from which a third high-frequency signal is output; a second transistor having an emitter electrically connected to the common potential, a base to which a second high-frequency signal is input, and a collector from which a fourth high-frequency signal is output; a first capacitance circuit electrically connected between the collector of the second transistor and the base of the first transistor; and a second capacitance circuit electrically connected between the collector of the first transistor and the base of the second transistor.