Bi-Directional Active Combiner-Splitter With Shared Matching Networks
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Solution Overview
Problem
Conventional bi-directional amplifiers and combiners in phased-array antennas face design constraints such as limited gain, output power, large size, and high passive trace loss, particularly in multi-beam TDD phased-array antennas, due to the need for input/output switches and passive matching networks, which hinder efficient beamforming and signal processing.
Innovation Solution
A bi-directional active combiner and splitter using bi-directional variable gain amplifiers (BD_VGAs) with cascode transistor pairs and shared matching networks, eliminating the need for input/output switches and reducing passive trace loss, enabling compact size, high efficiency, and precise gain control while maintaining high input-output isolation and phase invariance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passive combiner and splitter implementation (Wilkinson or Rat Race) is used, then the structure is simple and reliable, but the area occupied is large, loss is high, and bandwidth is limited
Solution Approach 1:
The patent combines multiple combiner functions into a single active combiner circuit using transistors and controlled switches, replacing the need for separate passive combiner networks. This merging of functions reduces the overall area while maintaining reliability through active signal management.
Solution Approach 2:
The patent introduces dynamically controllable switches and transistors that can adjust their state based on signal direction and gain requirements. This dynamic control allows the same circuit to function as both combiner and splitter, reducing the need for multiple static passive networks and thereby reducing area.
2Device complexity
If conventional passive combiner and splitter implementation is used, then the structure is simple, but the loss is large and bandwidth is limited
Solution Approach 1:
The patent replaces passive electromagnetic coupling mechanisms with active transistor-based signal combining and electronically controlled switching. This substitution allows for lower loss by using active components that can amplify and actively manage signals rather than relying on passive coupling that inherently loses energy.
Solution Approach 2:
The patent uses controllable switches and transistors to dynamically change circuit parameters such as impedance and signal path resistance. By optimizing these parameters through active control, the circuit achieves lower loss compared to fixed passive networks while managing complexity through integrated control.
3Ease of operation
If conventional active combiner and splitter with input and output switches is used, then gain control is possible, but the area is large and switch loss occurs
Solution Approach 1:
The patent designs a universal active combiner circuit that can function as both combiner and splitter, and can operate in multiple gain modes without requiring separate input and output switches. The same transistor and switch network performs multiple functions, reducing area while maintaining gain control capability through integrated control logic.
Solution Approach 2:
The patent merges the functions of input switching, output switching, and gain control into a single integrated active combiner circuit. By combining these previously separate functions into one unified structure, the area is reduced while gain control is maintained through the integrated control mechanism.
4Area of stationary object
If conventional bi-directional amplifier without input/output switch is used, then area is reduced, but design constraints in matching network limit the gain and output power
Solution Approach 1:
The patent introduces dynamically controllable switches within the matching network that can adjust the network configuration based on operating conditions. This dynamic adjustment allows the matching network to optimize for both gain and output power without requiring separate input/output switches, maintaining compact area while overcoming the power limitations of static matching networks.
Data Source
AI summary
A bi-directional active combiner and splitter using bi-directional variable gain amplifiers (BD_VGAs) is proposed. Advantages of the proposed bi-directional active combiner and splitter includes the following 1) compact size—for each BD_VGA, cascode transistor pair is small and the same matching network is used by the cascode transistor pair for both directions; 2) high efficiency—no switching loss in signal path, only switched matching; 3) reduced passive trace loss and power consumption—simplified signal interconnection; 4) active current combining—eliminates large size in the passive combiner; 5) high input-output isolation—cascode and neutralization; 6) precise gain control and unequal combining or splitting—changing the gain of the BD_VGA; and 7) phase-invariant amplifier design.