Lambda-Diode

Lambda diode is a basic electrical circuit having two terminals, which consists of two junction field- effect transistors ( JFETs ), and similarly to a tunnel diode in its characteristic having a negative differential resistance. The name references the U / I characteristic curve, which has the shape of the Greek letter λ (lambda ).

Applications

In contrast to the tunnel diode, the differential negative resistance is in the range from 70 mV to 350 mV, have lambda diodes on a differential negative resistance over the range of 1.5V to 6V. Areas of application are, as with tunnel diodes, primarily in the field of oscillators, where the differential negative resistance is used to generate oscillations. Due to the larger dynamic range, they offer technical advantages over circuit tunnel diodes. But since there is no quantum mechanical tunneling effect, they are not as fast and not up to such high frequencies used as tunnel diodes.

Other applications include low-power digital circuits based on combinations of modified lambda diodes. So that, similarly as in CMOS technology, metal -oxide-semiconductor field-effect Transistorn (MOSFETs ) can be implemented with logic gates, such as JFETs AND gates, OR gates and NOT gates. However, since let MOSFETs in integrated circuits integrate with a smaller footprint, JFETs have in this scope to only a small practical significance. Further, bi-stable flip-flop circuits for memory cells can be realized by means of lambda diodes.

In addition to the version with one N- channel and a P- channel JFET, as shown in the adjacent figure, lambda diodes can also be implemented as a combination of an N- channel JFET with a PNP bipolar transistor and two resistors.