# Calculation of Breakdown Voltage

How can we calculate the breakdown voltage of a BJT in ADS?

Is it Possible or not in ADS?

Problem:- I have a ADS BJT model. I am using that to generate high voltage output. For that i need to bias the transistor as class C amplifier with biasing volatge 10 V to get the distortion less signal (In ADS, Collector output voltage without coupling capacitor is attached). My input signal is Gaussian in nature with voltage swing 0V to 8V. I am getting my output in ADS environment but don't know whether it will work or not?

How can will I be sure that my design will work properly if realized?

Thanks

• What is ADS - is it a sim? – Andy aka May 24 '16 at 9:56
• The question is not if it is possible in ADS, the question is is the effect modeled in the model of the BJT you're using. To check that, build a testbench where you stress the BJT and see where is shows breakdown. Now you just build "something" and you see "something else" and then blame that on the BJT's breakdown while having no proof that that is actually the issue. – Bimpelrekkie May 24 '16 at 10:20
• @Andyaka Yes HP/Agilent/Keysight ADS is an (RF) design environment that some people like to use. It uses blocks for certain functions, similar to Matlab Simulink. – Bimpelrekkie May 24 '16 at 10:22
• If ADS lets you do it, please try to export the BJT-model and post it here. – Ariser May 24 '16 at 11:26

I think there are two things you should be checking when using the transistor model for your BJT in ADS. First, you should check if the vendor model for the transistor you're using takes into account the breakdown electric field of the BJT, which will be some sort of Zener or avalanche diode from the base to ground in the SPICE model. Second, since you have a "large signal" input you should check if the model you are using is a large signal or small signal amplifier model. Your transistor will behave quite differently with $V_{EB} \gg V_T$.