Neutralized Differential Bi-Directional Amplifier Without T/R Switch Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The transition to 5G wireless technology faces challenges due to high loss in passive T/R modules, which increases design complexity and compromises bidirectionality, and existing solutions either tolerate high loss or forfeit bidirectional benefits.
Innovation Solution
A switchless bi-directional amplifier (BDA) using cross-coupled differential amplifier pairs with neutralized common-emitter or common-source configurations and on-chip transformer-based baluns for single-ended measurement, enhancing performance by leveraging the OFF amplifier's parasitics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If passive T/R modules are used to achieve bidirectional signal flow, then bidirectionality is maintained, but high loss occurs
Solution Approach 1:
The amplifier is segmented into two separate amplifier pairs (first and second pairs) that can be independently controlled. Each pair handles one direction of signal flow, allowing the system to maintain bidirectionality while minimizing loss by activating only the necessary amplifier pair for each transmission direction.
Solution Approach 2:
The amplifier implements dynamic switching between two operational states by controlling the biasing of amplifier pairs. The system transitions between having the first amplifier pair active (for forward direction) and the second amplifier pair active (for backward direction), optimizing performance for each direction without the loss associated with passive components.
2Loss of energy
If unidirectional interstage amplifiers are used to compensate for high loss, then signal loss is reduced, but bidirectional capabilities are forfeited
Solution Approach 1:
The amplifier design makes each amplifier pair capable of handling both directions of signal flow. The first amplifier pair can amplify forward signals, and the second amplifier pair can amplify backward signals, creating a universal amplification system that maintains bidirectional capability while providing active amplification compensation for loss in both directions.
3Adaptability or versatility
If SPDT switches are added for signal routing to maintain bidirectionality, then bidirectional signal flow is enabled, but system complexity increases
Solution Approach 1:
The design extracts and eliminates the SPDT switching component from the signal path. Instead of using switches to route signals between fixed amplifier stages, the invention directly connects both amplifier pairs to the signal path with independent bias control, removing the switching complexity while maintaining bidirectional functionality.
4Adaptability or versatility
If SPDT switches are added for signal routing, then bidirectional signal flow is enabled, but additional loss is introduced
Solution Approach 1:
The invention converts the potential harm of having inactive amplifier components into a benefit by using the OFF amplifier pair's parasitic elements constructively. The parasitic capacitances and inductances of the inactive amplifier pair are utilized to maintain proper impedance matching and signal integrity, eliminating the need for lossy SPDT switches while preserving bidirectional capability.
Data Source
AI summary
A bi-directional amplifier (BDA) comprises a first pair of amplifier transistors and a second pair of amplifier transistors, wherein the first pair of amplifier transistors are cross-coupled with the second pair of amplifier transistors, and wherein the first pair of amplifier transistors and the second pair of amplifier transistors each comprise a differential common-emitter (CE) pair (or common-source (CS) pair) with equal transistor size or different transistor size. The BDA further comprises a plurality of blocking capacitors to decouple the collector and the base biases of the first pair of amplifier transistors and the second pair of amplifier transistors. Alternatively or additionally, the BDA further comprises two input/output baluns, through which a common voltage bias is applied to the collectors of each of the differential CE pairs (or drains of CS pairs in some implementations). The baluns enable single-ended measurement and characterization.