Interpreting InGaP/GaAs DHBT Eye diagrams using small signal parameters

In this paper we present measurement of eye patterns and their analysis for InGaP/GaAs DHBTs between 1 and 3 Gb/s PRBS signal. Eye diagrams have been measured and also simulated for comparison and further analysis. By adopting a robust direct parameter extraction technique all the small signal parameters of the DHBTs are deduced and are then used to simulate the corresponding eye patterns. The necessary procedure for simulating eye patterns is established in ADS so as the extraction of important eye parameters such as the eye height, amplitude, signal to noise ratio, rise and fall times. The eye parameters deteriorate with increase in frequency leading to the closure of the eye. An attempt has been made to recognise the main physical parameters of the device which influence the shape and formation of the eye diagrams and the observations has been discussed in this paper. These results provide an insight into device optimisation for user specified eye diagrams.