Receiver Amplifier Switch-Off Circuit for Overload Protection
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Solution Overview
Problem
Receiving modules in transmitter/receiver systems are prone to overdriving due to internal or external interference, leading to amplifier overload, which can result in interruption or destruction of the input module and subsequent electronics, especially with GaN technology, where high power levels and limited isolation between transmit and receive paths exacerbate the issue.
Innovation Solution
A circuit arrangement that includes a switch-off device for the amplifier, controlled via a control voltage and supply voltage, which sets both to zero potential during critical states, preventing amplification and thus protecting the amplifier and downstream electronics from excessive power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power limiter is placed in front of the LNA to prevent overload, then the LNA is protected from interference, but the received signal is attenuated and noise figure deteriorates
Solution Approach 1:
The invention dynamically adjusts the gate voltage of the LNA based on the detected signal level. When a high power signal is detected, the gate voltage is reduced to lower the amplifier's power consumption and prevent overload. When the signal level is normal, the gate voltage is restored to optimal values for low noise figure. This dynamic adaptation eliminates the need for continuous signal attenuation while maintaining protection capability.
Solution Approach 2:
The invention changes the operating parameters of the LNA by adjusting the gate voltage in response to signal conditions. Instead of using a fixed power limiter that always attenuates signals, the gate voltage is varied to match the actual signal environment, thereby maintaining optimal noise figure during normal operation while preventing overload during high power events.
2Productivity
If the LNA operates continuously to maintain reception capability, then reception is available, but the amplifier is vulnerable to overload from high power signals
Solution Approach 1:
The invention implements a feedback mechanism where the signal level is continuously monitored and used to control the gate voltage of the LNA. When high power signals are detected, the feedback loop reduces the gate voltage to prevent overload. This allows the LNA to remain operational and adaptive to varying signal conditions without being permanently vulnerable to overload.
3Reliability
If the gate voltage is reduced during high power signals to prevent overload, then the LNA is protected, but power consumption increases
Solution Approach 1:
The invention applies periodic or temporary reduction of gate voltage only during high power signal events rather than continuously. This pulsed adjustment approach reduces power consumption compared to continuous operation at reduced voltage, while still providing protection when needed. The gate voltage is restored to normal levels during typical operation to minimize power consumption.
Data Source
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AI summary
A circuit arrangement for protecting a receiving module (40) or subsequent electronic circuitry (60) is disclosed. The circuit arrangement comprises: an amplifier (110) with an input (112) and an output (114), which can be coupled to the following circuit electronics (60), a control module (120) which is designed to in a potentially critical state for to output a control signal (125) for the amplifier (110) or for the receiving module (40) or for the subsequent circuit electronics (60), and a switch-off device (130) which is designed to switch off the amplifier (110) in response to the control signal ( 125) to switch off, the switched-off amplifier (110) not amplifying signals at the input (112), but weakening the signals at the input (112) by partial or complete absorption or reflection.