Diode Detector Simulation using EEsof ADS Software - App Note

This application note has been written to demonstrate how the Avago Technologies EEsof ADS software package can be used to simulate a diode detector circuit reliably against temperature. For this demonstration a simple two diode configuration has been proposed. This has the benefit of offering temperature compensation of the diode's bias-induced forward voltage. The circuit used in this demonstration is shown in Figure 1 below. This circuit was designed around the Avago Technologies Schottky diode, HSMS-2865, which was developed for low cost, high volume, high frequency detector applications. The input impedance in this example was chosen to be 33 Ohms. L1 and C2 are providing the reactive match, while R1 provides a good broadband resistive match. The bias is applied to the first diode via R1, and R2 acts as the resistive load for the detector's output voltage. The second diode has an identical DC chain, and therefore the same forward current, assuming the diode's dc characteristics are identical. To achieve almost identical dc characteristics, the dice in a SOT-143 are selected from adjacent sites on a wafer, thus ensuring the best possible match between the two diodes. Vbias is selected in this example to give a bias current of 5 µA.