Multi-Band Low Noise Amplifier Without Band Selection Switch Loss
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Solution Overview
Problem
The band selection switch in low noise amplifiers (LNAs) causes insertion loss, which increases the overall noise figure, especially when handling multiple frequency bands.
Innovation Solution
The low noise amplifier is designed with multiple transistors and inductors that can selectively amplify RF signals in different frequency bands by adjusting bias voltages, thereby eliminating the need for a separate band selection switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a band selection switch is used to handle multiple frequency bands, then multi-band operation capability is improved, but insertion loss increases and noise figure deteriorates
Solution Approach 1:
The LNA is divided into multiple independent amplification paths, each dedicated to a specific frequency band with its own transistor pair (first and second transistors for first band, third and fourth transistors for second band). Each path can be independently activated or deactivated through bias voltage control, eliminating the need for signal routing through a band selection switch and thereby reducing insertion loss while maintaining multi-band capability.
2Adaptability or versatility
If a band selection switch is used to handle multiple frequency bands, then multi-band operation capability is improved, but noise figure increases
Solution Approach 1:
The LNA is divided into multiple independent amplification paths, each dedicated to a specific frequency band with its own transistor pair (first and second transistors for first band, third and fourth transistors for second band). Each path can be independently activated or deactivated through bias voltage control, eliminating the need for signal routing through a band selection switch and thereby reducing insertion loss while maintaining multi-band capability.
3Loss of energy
If multiple transistor paths are used for multi-band operation, then insertion loss is reduced, but device complexity increases
Solution Approach 1:
Each transistor pair (first and second transistors, third and fourth transistors) is designed to handle multiple functions: amplification for its designated frequency band and automatic deactivation for other bands through bias voltage control. The shared bias voltage control mechanism and power supply network provide universal management across all frequency paths, reducing overall system complexity despite multiple amplification paths.
Solution Approach 2:
The bias voltage levels (first, second, third, and fourth bias voltages) are dynamically adjusted to control the operational state of each transistor pair. By changing the bias voltage parameters, the LNA can switch between different frequency bands without physical reconfiguration, simplifying the control mechanism while enabling multi-band operation with reduced insertion loss.
Data Source
AI summary
A low noise amplifier is provided. The low noise amplifier includes a first transistor configured to amplify an input radio frequency (RF) signal of a first frequency band, and configured to receive a first bias voltage, a second transistor configured to amplify an input RF signal of a second frequency band, and configured to receive a second bias voltage, a third transistor configured to amplify an output RF signal of the first transistors and configured to receive a third bias voltage, and a fourth transistor configured to amplify an output RF signal of the second transistor, and configured to receive a fourth bias voltage. In a first operation mode, the second bias voltage and the fourth bias voltage may be set to an off-voltage level, and in a second operation mode, the first bias voltage and the third bias voltage may be set to the off-voltage level.