Q-Band Monolithic GaAs PHEMT Low Noise Amplifiers: Comparative Study of Depletion and Enhancement Mode Transistors

Two Q-band monolithic low noise amplifiers have been designed and characterized. A study about depletion and enhancement mode HEMTs with the same technology has been performed in order to apply these results to the design of the low noise amplifiers. These circuits have been developed for being used in the Back End module of the radiometers in the European Scientific mission Planck, because there are not commercial circuits available in this frequency band. The main goals for these amplifiers are low noise with a small DC consumption. A minimum noise figure of 2.8 dB with an associated gain of 23.1 dB at 40.4 GHz has been measured for the E-HEMT MMIC LNA and its DC current consumption was 15.4 mA. The D-HEMT MMIC LNA has a minimum noise figure of 3 dB with an associated gain of 23.2 dB at 42 GHz and 30 mA of DC current consumption