In 1938 Schade proposed a mechanism to transform a pentode tube into a triode by connecting the plate to the grid using a resistor network. Here is the graphs from his work "Beam Power tubes" by O. H. Schade, March 1938.
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| "Beam Power tubes" by O. H. Schade, March 1938 |
The same can be done with JFETs. Let us take a BS170 (http://www.fairchildsemi.com/ds/BS/BS170.pdf) MOSFET. I'm using TINA-TI for the simulations. Here is the schem for the simulation
The next graph shows the drain current as a function of drain voltage for various values of the gate voltage (from 6V - upper curve, to 0V).
The relation between the drain current and the gate-to-source voltage is
where Vth is the turn on threshold voltage and it has the typical value of 2.1V.
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Last updated: 16-02-2026 [16:02]
For attribution, please cite this page as:
Charters, T., "Mostrode: a mosfet approach to the triode 3/2 law": https://nexp.pt/mostrode.html (16-02-2026 [16:02])
(cc-by-sa) Tiago Charters - tiagocharters@nexp.pt
