Multi-Band Amplifier Circuit With Switched Path Isolation
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Solution Overview
Problem
In amplifier circuits supporting multiple frequency bands, unused amplifiers cause load effects that deteriorate the performance of active amplifiers, and reducing these effects with external passive components is costly and difficult, especially in terms of size reduction.
Innovation Solution
The amplifier circuit design includes a first and second power amplifier with transistors and switches that isolate input signals between different frequency bands, using capacitors and inductors for impedance matching and parasitic capacitor management to reduce interference and load effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple amplifiers are coupled together to support multiple frequency bands, then the amplifier circuit can process signals of different frequency bands, but the unused amplifier causes a load effect to the amplifier in use, deteriorating its performance
Solution Approach 1:
The amplifier circuit is segmented into multiple independent amplifier units, each handling a specific frequency band. Switches are introduced to segment the signal paths, allowing only the required frequency band to be connected to the output while isolating other bands. This segmentation prevents the load effect from spreading across all amplifiers and confines it to only the active path.
Solution Approach 2:
Switches are introduced as intermediary components between the multiple amplifiers and the output terminal. These switches act as mediators that selectively connect or disconnect specific amplifier paths based on the required frequency band, thereby preventing the load effect from affecting the active amplifier while maintaining multi-frequency band support.
2Reliability
If external passive components are installed on the circuit board to reduce the load effect, then the load effect is reduced, but the cost increases and the size of the components is difficult to reduce
Solution Approach 1:
The invention extracts the load effect problem from the amplifier circuit by introducing switches that actively disconnect unused amplifier paths. Instead of using external passive components to mitigate the load effect, the solution removes the source of the problem by isolating the inactive amplifiers from the output terminal, thereby eliminating the need for additional passive components.
Solution Approach 2:
The invention replaces the passive mechanical approach (using external passive components to reduce load effect) with an active electronic control approach (using switches to actively disconnect unused paths). This substitution eliminates the need for additional passive components and their associated size and cost constraints.
Data Source
AI summary
An amplifier circuit includes a first amplifier and a second amplifier. The first amplifier receives a first signal and generates a first amplification signal accordingly. The second amplifier receives a second signal and generates a second amplification signal accordingly. The first signal is related to a first frequency band, and the second signal is related to a second frequency band different from the first frequency band. When one of the first amplifier and the second amplifier is in use, the other one of the first amplifier and the second amplifier is unused. The first amplifier and second amplifier are coupled to a reference voltage terminal through a common node. The first amplifier includes a switch coupled between the common node and a stage of the first amplifier, and the switch can be controlled for reducing the loading effect caused by the first amplifier on the second amplifier.