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Lambda diodes work at higher voltage than tunnel diodes. Whereas a typical tunnel diode 1N3712 data sheet. may exhibit negative differential resistance approximately between 70 mV and 350 mV, this region occurs approximately between 1.5 V and 6 V in a lambda diode due to the higher pinch-off voltages of typical JFET devices. A lambda diode therefore cannot replace a tunnel diode directly.
Moreover, in a tunnel diode the current reaches a minimum of about 20% of the peak current before rising again towards higher voltages. The lambda diode current approaches zero as voltage increases, before rising quickly again at a voltage high enough to cause gate–source Zener breakdown in the FETs.
It is also possible to construct a device similar to a lambda diode by combining an n-channel JFET with a PNP bipolar transistor. Oscillations and Regenerative Amplification using Negative Resistance. A suggested modulatable variant but is a bit more difficult to build uses a PNP based optocoupler and can be tweaked by using its IR diode. This has the advantage that its properties can be fine tuned with a simple bias driver and used for high sensitivity radio applications. Sometimes, a modified open can PNP transistor with IR LED can be used instead.
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