Layout design considerations for 60 GHZ SiGe power amplifiers

In this work we report on the importance of electromagnetic analysis for the layout design of monolithic 60 GHz power amplifiers (PA) in SiGe HBT technology. To facilitate this, two different layouts of the same circuit architecture were investigated. The circuits were originally designed using the circuit simulator of Agilentpsilas ADStrade and realized in a high performance 0.25 mum SiGe BiCMOS process with f_t and f_max ap 200 GHz. The two implementations differ only in the layout arrangement of the power stage transistors. Though the simulations without electromagnetic analysis for the power stage showed very similar results for both layout versions, the measurements disagreed seriously. 2frac12 D-EM analyses of both layouts using ADS-Momentumtrade were performed to clarify this issue. The EM post simulations delivered a good agreement with measurements and the frequency shift of the small signal gain could be explained this way. With one layout version a very good overall power performance was achieved: 15 dBm output power with 19.7 % PAE at 61 GHz.