Design and Characterization of MMIC IF VGA and Small Signal CMOS Millimeter Wave Amplifiers

Licentiate thesis, 2006

The main aim of this work is to demonstrate the easibility of designing and characterizing monolithic microwave integrated circuit (MMIC) variable gain amplifiers (VGA) and small signal amplifiers in III-V (GaAs) and 90 nm CMOS technologies, respectively. The VGA is studied at the IF frequency of 2.5 GHz whereas the CMOS amplifiers were investigated at 20 GHz and 40 GHz, respectively. Two different approach of Back-End-of-Line (BEOL) technology on the multi-layer silicon substrate, both with and without BCB (benzocyclobutene) have been investigated in two successive phases. The first part of the thesis starts with a theoretical as well as analytical investigations of variable gain amplifiers with the aim of using it in the IF block of a demonstrator particularly for millimeter-wave applications. The MMIC implementations then follows based on a suitable, source feed back topology using a commercial pseudomorphic High Electron Mobility Transistor (pHEMT). A maximum gain control of 45 dB has been obtained with the maximum gain of 47 dB. Minimum NF obtained at the highest gain mode is 0.78 dB and the output compression is -7 dBm (approx.). Results obtained from measurement and simulations were analyzed and compared with the published works of other topologies as well as technologies. External foundries were used to process the MMICs for the work. The second part of the thesis gives a brief overview of 90 nm CMOS technology and then discusses mainly the design approach and the amplifier performances. With BEOL, the gain obtained from 20 GHz single stage amplifier was 5.8 dB with a NF of 5.4 dB. Corresponding figures for the 40 GHz amplifier was 6 dB and 7.8 dB respectively.