MOS-Varactor simulation model helps Toshiba to build RF CMOS chips up to 60GHz

Toshiba Corporation has developed compact MOS-Varactor simulation model in cooperation with researcher Professor Nobuyuki Itoh of Okayama Prefectural University.

The new compact MOS-Varctor model introduces an original algorithm to express scaling effects and can capture the impacts of parasitic effects that dominate in the 60 GHz region. Measurement parameters from 1MHz to 60 GHz for samples with different cell sizes were used for modeling. In general, it is difficult to express MOS-Varactor with a single model, but this newly developed model fully succeeds, says Toshiba.

The new model helps in realization of low power consumption in RF-CMOS products. Toshiba to leverage this model in developing its advanced RF ICs based on CMOS. The new model has been verified with samples with cell lengths ranging from 0.26 µm to 2.0 µm formed with Toshiba's 65nm RF-CMOS technology. Very good accuracy for all cell sizes was achieved from DC to 67 GHz, claims Toshiba.

Toshiba has tested this model on a 60GHz RF circuit, and it has measured and compared phase noise level dependency on the control voltage of the 60 GHz VCO with a circuit simulation, with this model used in the frequency tuning block. Toshiba found measurement accuracy was found to be 8 dB better than with the conventional model.