60-GHz flip-chip assembled MIC design considering chip-substrate effect

In this paper, 60-GHz microwave integrated circuits (MIC´s) with flip chip assembled 0.1-μm-gate GaAs pseudomorphic high electron-mobility transistors (p-HEMT´s) are demonstrated. To clarify the millimeter-wave characteristics of the flip-chip assembled structure, the parameters for the assembly equivalent circuit are examined using three-dimensional (3-D) electromagnetic-field analysis. The analytical results indicate that the optimum height of the bump is 30 μm to minimize degradation of the millimeter-wave characteristics. A 60-GHz-band MIC two-stage amplifier and 30/60-GHz frequency doubler designed using the results of the field analysis have been fabricated. The amplifier has maximum gain of 12.8 dB at 58.6 GHz, P_1dB of 12.9 dBm has been obtained at 60 GHz. A 30/60-GHz frequency doubler has maximum conversion gain of 0.4 dB and fundamental frequency suppression of -23.0 dB at the input frequency of 30.4 GHz. Good agreement between the measured and the simulated results demonstrates the potential of the structure and design method