I'm following a paper, using ADS, to find the input impedance of a shunt Schottky diode. The paper's schematic is Fig. 1, and my schematic is Fig. 2. The point is that, I could not get the same result as the paper reported. Here is their steps and my corresponding results:
Their method: Shorterning the Impedance Matching tool, varying Pin. It was said the rectifier operates optimally when the diode's peak reverse voltage, Vr_max reaches Bv(6.4V as in the model). So, they found Vr_max = 6.4V @ Pin = 12.320 dBm (Fig. 3).
My results: Vr_max = peak(Vd). With Pin in the range (-5,15), my Vr_max could not reach 6.4V. At Pin = 12.320 dBm, my Vr_max = 4.509V while Vout = 2.599V (Fig.4). Therefore Zin (input impedance) is totally different than the paper's findings. Could anyone tell me what I did wrong?