A large signal model of the inverted InGaAs/InAlAs/InP HBT for harmonic distortion analysis

A large signal equivalent circuit based on the Ebers-Moll model is developed for the InGaAs/InAlAs/InP collector-up HBT. The parasitic elements of the equivalent circuit are extracted at COLD (zero) bias by numerical optimization. An analytical approach is used to extract the intrinsic parameters of the small signal equivalent circuit at non-zero bias points. Appropriate equations given by device physics are fitted to the bias variation of intrinsic parameters so that the Ebers-Moll model parameters can be extracted. Harmonic distortion analysis is performed to verify the resulting HBT model. Excellent agreement between measurements and simulations is achieved at the fundamental and second harmonic frequencies. The agreement is not as good at the third harmonic frequency. This could be due to the fact that measurement inaccuracy exists in the lower drive level and the f_max of the device is very close to the third harmonic frequency