9-2015

RF & WirelessSoftwareMACOM Designs Ka-Band MMIC PowerAmplifier With NI AWR Design EnvironmentFigure 1: Block diagram of the MMICFigure 2: 3D Analyst layout view showing bond wires„NI AWR Design Environmentprovides a one-stop shop forthe entire design phase, fromcircuit design andEM simulation through tolayout and reticle design. Theintegrated nature reducesthe risk of errors in a costlyMMIC process and providesan excellent platform formanaging and reporting on allaspects of the design.“Thomas Young,Senior Design Engineer,MACOM, macom.comThe Design ChallengeFigure 3: Measured v. simulated for PAE and P out .MACOM designers were developinga high-frequency, fourstage,monolithic microwaveintegrated circuit (MMIC) design(Figure 1) that required extensiveEM simulation at a relativelyearly stage in the designprocess. A large signal simulationof an extensive array ofsaturated transistor cells withgood convergence in a reasonabletime was called for. In particular,a 3D EM simulation ofthe RF bond wire transition wasneeded (Figure 2 ), as well as a2.5D (3D planar) EM simulationof the IC elements and a fulllarge-signal simulation and optimizationof the power amplifier(PA). Foundry models availablefor the 0.15 µm gallium arsenide(GaAs) process were used for theinitial idealized design.Specific design requirementsincluded a competitive size withfrequency range of 32 to 38 GHz,P out greater than 4 W, 18 dB gainfully matched to 50 ohms, continuouswave (CW) and pulsedoperation, and on-chip decouplingand electrostatic dischargeprotection.The SolutionMACOM designers used NIAWR Design Environment softwareinclusive of MicrowaveOffice circuit design software,AXIEM 3D planar EM simulator,Analyst 3D FEM simulator,and APLAC harmonic balance(HB) simulator. The softwareenabled them to successfullydesign and simulate the 4 WKa-band PA using a 2 mil thick0.15 µm GaAs pseudomorphichigh-electron mobility transistor(pHEMT) process. The designersachieve saturated outputpower in excess of 4 W over64 hf-praxis 9/2015