CMOS PA Matching Network With High-Impedance Turn-Off Isolation
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Solution Overview
Problem
In 5G TDD systems, the use of a TX switch in power amplifier networks leads to performance degradation due to insertion loss, and existing solutions waste PA output power, necessitating an efficient impedance matching solution for both TX and RX modes.
Innovation Solution
A wide band matching network incorporating a power amplifier transistor, an on-chip transformer, and a series capacitor, which acts as a second-order filter, allowing for impedance matching and impedance isolation based on the operational mode of the power amplifier and receiver, eliminating the need for a TX switch and optimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a TX switch is used in the power amplifier network for TDD systems, then the transmitter and receiver can be switched between modes, but insertion loss degrades the power amplifier performance
Solution Approach 1:
The patent removes the TX switch from the power amplifier network entirely. Instead of using a switch to separate TX and RX paths, the design extracts the switching function by using the power amplifier's own output impedance characteristics - when the PA is turned off, its output naturally presents a high impedance state that isolates the RX path without requiring an additional switch component, thereby eliminating insertion loss while maintaining TDD operation capability
Solution Approach 2:
The power amplifier transistor serves multiple functions: when ON, it amplifies and transmits signals; when OFF, it naturally provides high impedance isolation for the receiver path. This multi-functionality eliminates the need for a separate TX switch, as the PA itself performs both the amplification and the path isolation functions through its operational states
2Adaptability or versatility
If a TX switch is used to separate TX and RX paths, then mode switching is enabled, but the switch degrades power amplifier performance
Solution Approach 1:
The TX switch is completely removed from the system. The patent extracts the switching function by utilizing the inherent high impedance state of the power amplifier when turned off, which naturally isolates the receiver path without requiring an external switch, thereby eliminating the performance degradation caused by switch insertion loss and non-linearities
Solution Approach 2:
The matching network serves as an intermediary between the power amplifier and the antenna/RX path. It is designed to provide proper impedance transformation when the PA is ON for transmission, and to maintain appropriate impedance levels when the PA is OFF to prevent signal leakage into the PA, thereby protecting PA performance without requiring a switch
3Power
If existing solutions are used for impedance matching, then TX mode operation is supported, but RX mode operation causes signal interference and power waste
Solution Approach 1:
The matching network is designed with dynamic characteristics that adapt to the operational state of the power amplifier. When the PA is ON, the matching network provides optimal impedance transformation for maximum power transfer to the antenna. When the PA is OFF, the matching network's impedance characteristics change to present a high impedance state that prevents receiver signals from being reflected back into the PA, thereby eliminating signal interference and power waste in RX mode
Solution Approach 2:
The patent utilizes parameter changes in the power amplifier's output impedance based on its operational state. When the PA is turned off, its output impedance naturally transitions to a high impedance state. The matching network is designed to exploit this parameter change, transforming the high impedance to appropriate levels that prevent signal interference during RX operation while maintaining optimal matching during TX operation
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 matches impedance for power amplifiers in both TX-on and RX-off modes and isolates the receiver in RX-on modes, reducing signal interference and conserving PA output power, thereby enhancing overall system performance and efficiency.
Implementation Method 1
A wide band matching network for power amplifier impedance matching
Implementation Method 2
a series capacitor; an on-chip transformer connected to the capacitor in series
Implementation Method 3
an on-chip transformer connected to the capacitor in series, wherein the transformer and the capacitor act as a second order filter
Implementation Method 4
A wide band matching network for power amplifier impedance matching, the wide band matching network comprising: a power amplifier transistor connected to an output network
Data Source
AI summary
A wide band matching network for power amplifier impedance matching, the wide band matching network comprising: a power amplifier transistor connected to an output network; the output network including: a series capacitor; an on-chip transformer connected to the capacitor in series, wherein the transformer and the capacitor act as a second order filter; and a port connected to the capacitor and a receiver switch.