How to plot the I-V curve of a tunnel diode?
I am trying to understand tunnel diodes by experimenting with them. Research tells me they can have negative resistance, and can be used to build a high frequency oscillator. Tunnel diodes are supposed to have this I/V characteristic:
I don't really understand negative resistance, so I thought plotting the I-V characteristics myself would help me understand. Unfortunately, that didn't work.
What I did:
- Connect PSU in series with a protective, current limiting resistor, and the tunnel diode.
- Increase/decrease voltage level, in steps as fine as mV, and measure corresponding current values, as fine as 100 µA.
- Record each point on a graph of current as a function of voltage.
Here is my test setup:
As I increase voltage from 0 to IpeakV, the current increases as expected. Once approaching the IpeakV, the current suddenly jumped from tens of µA to some 400/500 mA. In other words, I just missed the most important measurements, those of the negative resistance region.
Why can I not measure the current as soon as the gradually increasing voltage V enters the negative region? How can I tell the tunnel diode not to "skip" the tunnel?