Distributed Amplifier Multiplexer for Wideband Channel Isolation
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Solution Overview
Problem
Conventional distributed active multiplexers suffer from narrow bandwidth and low isolation between input channels due to shared output transmission lines and parasitic capacitance effects.
Innovation Solution
A multiplexer design incorporating separate distributed amplifiers with 50Ω impedance matching and a passive multiplexer with 16.7Ω resistors to separate output transmission lines, reducing parasitic capacitance and improving signal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared output transmission line is used in a distributed active multiplexer, then device complexity is reduced, but bandwidth becomes narrow and isolation between input channels deteriorates
Solution Approach 1:
The patent divides the shared output transmission line into separate output transmission lines for each channel. Specifically, the first output transmission line is connected only to the first distributed amplifier and the second output transmission line is connected only to the second distributed amplifier. This segmentation eliminates the parasitic capacitance coupling between channels that occurs in shared lines, thereby widening the bandwidth and improving isolation between input channels while maintaining reasonable structural complexity
2Productivity
If separate output transmission lines are used for each channel, then bandwidth increases and isolation improves, but device complexity increases
Solution Approach 1:
The patent introduces a passive multiplexer as an intermediary component that combines the separate output transmission lines. The passive multiplexer includes resistors (R1=16.7Ω, R2=16.7Ω, R3=33.3Ω) that serve as mediators to combine the signals from separate transmission lines while maintaining impedance matching and preventing signal interference. This allows the system to enjoy the benefits of separate lines (wide bandwidth, good isolation) without the full complexity of completely independent output paths
3Reliability
If impedance matching is optimized for 50Ω, then signal transmission quality improves, but parasitic capacitance effects increase bandwidth limitations
Solution Approach 1:
The patent changes the resistance values in the passive multiplexer to specific optimized parameters: R1=16.7Ω, R2=16.7Ω, and R3=33.3Ω. These parameter changes are specifically designed to compensate for parasitic capacitance effects while maintaining 50Ω impedance matching at the interfaces. By carefully selecting these resistance values, the system achieves both good signal transmission quality and extended bandwidth beyond what conventional 50Ω matching alone could provide
Data Source
AI summary
An embodiment is a multiplexer including a first distributed amplifier with an impedance matched to 50Ω, the first distributed amplifier configured to receive a first signal and output a first amplified signal, a second distributed amplifier with an impedance matched to 50Ω, the second distributed amplifier configured to receive a second signal and output a second amplified signal, and a passive multiplexer configured to multiplex the first amplified signal and the second amplified signal, and output a multiplexed signal to a signal output terminal, the passive multiplexer including a first resistor having a first end to receive the first amplified signal, a second resistor having a first end to receive the second amplified signal, and a third resistor having a first end connected to second ends of the first and second resistors and a second end connected to the signal output terminal.