MACOM Technology Solutions Holdings Inc. is a leading supplier of high performance analog RF, microwave, millimeter wave, and photonic products that enable next-generation Internet and modern battlefield applications. Recognized for its broad catalog portfolio of technologies (GaN, GaAs, InP, SiGe, HMIC and silicon) and products, MACOM serves diverse markets, including high speed optical, satellite, radar, wired and wireless networks, automotive, industrial, medical, and mobile devices. MACOM designs and manufactures standard and custom devices, integrated circuits, components, modules, and assemblies for customers who demand high performance, quality, and reliability.

The Design Challenge

MACOM designers were developing a high-frequency, four-stage, monolithic microwave integrated circuit (MMIC) design that required extensive EM simulation at a relatively early stage in the design process. A large signal simulation of an extensive array of saturated transistor cells with good convergence in a reasonable time was called for. In particular, a 3D EM simulation of the RF bond wire transition was needed, as well as a 2.5D (3D planar) EM simulation of the IC elements and a full large-signal simulation and optimization of the power amplifier (PA). Foundry models available for the 0.15 um gallium arsenide (GaAs) process were used for the initial idealized design. Specific design requirements included a competitive size with frequency range of 32 to 38 GHz, Pout greater than 4 W, 18 dB gain fully matched to 50 ohms, continuous wave (CW) and pulsed operation, and on-chip decoupling and electrostatic discharge protection.

The Solution

MACOM designers used NI AWR Design Environment™ software inclusive of Microwave Office circuit design software, AXIEM 3D planar EM simulator, Analyst™ 3D FEM simulator, and APLAC harmonic balance (HB) simulator. The software enabled them to successfully design and simulate the 4 W Ka-band PA using a 2 mil thick 0.15 um GaAs pseudomorphic high-electron mobility transistor (pHEMT) process. 

The designers achieve saturated output power in excess of 4 W over the full 32-38 GHz bandwidth, with gain of 19 dB and power-added efficiency (PAE) in the region of 23 percent.

Excellent performance was verified under both CW and pulsed conditions. The results justified the design approach in terms of device modeling, circuit design, EM simulation, and even thermal considerations. 

The design team noted that with AXIEM, EM simulations were quick to set up and it was easy to adjust geometry dimensions for performance tuning. Simulation times were reasonable even when simulating from a laptop. Integration with the layout through NI AWR Design Environment ensured consistency between EM and layout. The APLAC HB engine was fully capable of handling large transistor array simulations with good convergence across the band. The team was especially impressed with the ease of management of the entire design project from measured cell data, EM designs, layout, and reticle design, through to exporting graphs and graphics for reporting.

Why NI AWR Design Environment

The MACOM designers chose NI AWR software because of their familiarity with the tool and its intuitive user interface including high-quality layout. The key benefit was excellent correlation between the simulations and measurements. NI AWR Design Environment delivered higher productivity thanks to its ease of use, integration with third-party tools, and superior technical support.