Power Amplifier Base-Emitter Capacitor for High-PAE Output
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Solution Overview
Problem
Power amplifiers in mobile communication devices experience a decrease in power added efficiency (PAE) at high output levels due to increased current flowing from the bias circuit into the base of the amplification transistor.
Innovation Solution
Incorporating a second capacitor connected between the base and emitter of the transistor, with its capacitance value similar to that of the transistor in the off-state, to improve power added efficiency by reducing bias current and optimizing the timing of transistor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If bias is supplied to the base of the amplification transistor using a conventional bias circuit, then the transistor can operate at high output power levels, but the current flowing from the bias circuit into the base increases, resulting in a decrease in power added efficiency
Solution Approach 1:
A capacitor is introduced as an intermediary element between the bias circuit and the base of the amplification transistor. This capacitor couples the bias signal to the base while blocking the DC component, thereby reducing the current drawn from the bias circuit and improving power added efficiency at high output power levels
Solution Approach 2:
The biasing parameters are modified by introducing a capacitor that changes the effective impedance seen by the bias circuit. This parameter change allows the transistor to operate at high output power while reducing the bias current consumption, thus improving power added efficiency
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 solution effectively enhances power added efficiency at high output power levels by reducing bias current and prolonging the off-state period, thereby improving overall efficiency.
Implementation Method 1
a first capacitor with a radio frequency signal input to a first end of the first capacitor; a first transistor whose base is connected to a second end of the first capacitor
Implementation Method 2
a second capacitor with a first end connected to the base of the first transistor and a second end connected to the emitter of the first transistor
Implementation Method 3
a first transistor whose base is connected to a second end of the first capacitor to amplify the radio frequency signal
Data Source
AI summary
The present disclosure is to improve the power added efficiency of a power amplifier at high output power. The power amplifier includes: a first capacitor with a radio frequency signal input to one end thereof; a first transistor whose base is connected to the other end of the first capacitor to amplify the radio frequency signal; a bias circuit for supplying bias to the base of the first transistor; and a second capacitor with one end connected to the base of the first transistor and the other end connected to the emitter of the first transistor.