Cree Inc of Durham,NC,USA has released a new suite of Verilog-A proprietary nonlinear device models for its gallium nitride(GaN)RF devices(available free to Cree's RF customers),developed for use with leading RF design platforms from Agilent ADS and AWR Microwave Office.Verilog-A is an industry-standard language used to describe transistor behavior for simulation purposes.
The new device models support more complex circuit simulations including modulation envelope analysis for use in the latest broadband and multi-mode RF power amplifiers for 4G cellular telecoms.The cross-platform models were made available on the Cree Model portal in connection with the 2012 IEEE MTT-S International Microwave Symposium(IMS)in Montreal,Canada(19-21 June).
"The release of this new suite of device models enables RF design engineers to predict nonlinear performance using harmonic balance,conduct robust transient analysis as well as use'real-world'arbitrary modulation signals with envelope simulation for Cree's GaN HEMT devices,"says Jim Milligan,director RF and microwave,Cree."The Verilog-A models,together with envelope simulators,allow designers to directly investigate higher-efficiency circuit approaches,such as Doherty amplifiers,to improve adjacent channel power ratios(ACPRs),spectral re-growth and error vector magnitude(EVM),while assessing if amplifier performance meets spectral mask requirements for LTE deployments.As these models also take advantage of multi-core processors,simulation times can be greatly reduced,"he adds.
"Transient analysis allows insight into switched-mode power amplifier configurations that may also be driven directly from digital signals,"says Ray Pengelly,RF business development manager,Cree."Combined with such approaches as Chireix out-phasing,unprecedented efficiencies of greater than 70%have been demonstrated."
