Low noise amplifiers for 94 GHz cloud radar

Four low noise amplifiers for 94 GHz cloud radar are presented. One LNA is designed using coplanar waveguides and the others use microstrip lines. The designed amplifiers were manufactured with a metamorphic high electron mobility transistor (MHEMT) technology and the chip size is 2.1 mm x 1.1 mm. The four stage LNAs have either 2x25 pm or 4x25 pm size MHEMTs. The scattering parameters and the noise figures of the amplifiers were measured at W-band and the results are presented. The best measured gain at 94 GHz was 16 dB and the noise figure 5.7 dB using a 2.5 V supply voltage and a drain current of 15 mA per stage. Furthermore, one of the amplifiers was assembled in a package that has WR-10 waveguide interfaces. The packaged chip exhibited 10.8 dB of gain and the noise figure was 8 dB at 94 GHz.