Project Details
Projekt Print View

Highly robust microwave low-noise amplifiers

Subject Area Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Term from 2017 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 387060302
 
Final Report Year 2023

Final Report Abstract

In radio receivers, the first component following the antenna is usually a low-noise amplifier (LNA). Its task is to amplify the typically very weak received input signal so that the inherent noise of the following electronics no longer represents a significant problem. This LNA is a delicate component, designed for very low received power and should also consume as little power as possible itself. However, a radio receiver does not only receive the desired signal. If there is a strong transmitter in its vicinity, the received power can easily exceed the intended power level by a factor of 1000. A common LNA will be destroyed in this case. Often the transmitting / receiving equipment itself transmits the strong signal, for example in case of a radar or a radio interface of a satellite. It is then necessary to protect the LNA from too much received power. Therefore, a protective circuit is commonly connected between the LNA and the antenna. It acts as an electronic fuse to short-circuit an excessively large signal at the antenna. However, this protective circuit cannot be integrated on a chip with the LNA. The system integration becomes more expensive, the setup large and heavy, and reliability suffers accordingly. In addition, a protection circuit attenuates the received signal and thus degrades the signal-to-noise ratio. It has been shown in the past that GaN-HEMT technology makes it possible to raise the maximum allowable input powers from typically 100 mW for a GaAs-based LNA to about 10 W for a GaN-based LNA. However, it should be noted that this success can be attributed to an improvement in the technology rather than in circuit topology. This is where this project started. A new circuit topology, in which the transistors are connected in series at the input, now not only increases robustness. It was shown that in the optimized case this is accompanied by only a moderate increase in the noise figure. Demonstrators at 5 and 10 GHz were manufactured as integrated circuits and characterized through measurement. Another important contribution of the project is the experimental investigation of the recovery time of the GaN-based LNAs after a pulse of high input power has decayed. Here, the relationship between deep level traps and recovery time was derived from pulsed dc measurements, and the dynamic small-signal behavior in response to a pulse of high input power was characterized.

Publications

 
 

Additional Information

Textvergrößerung und Kontrastanpassung