A Lambda diode osc. is actually realized with transistors inside a chip
normally. It is a negative resistance device so it only needs one port for
the LC or crystal. It also inherently limits the amplitude of the
oscillation to 1.2V pk-pk (more commonly 0.3-1.0 Vpkpk), and is suitable
for GDOs because you can easily turn it into a passive receiver/detector
and also adjust the gain. Many PLL chips and color/TV/video chips that
have the crystal or tank connected to only one pin and GND have lambda
diode o.'s. The low L.O. amplitude is good for low radiation/parasitics.
The associated tuned circuit is usually operated in series resonance
(this is favored by Rneg and the current drive output of the device).

You can make your own using an emitter coupled pair of NPNs. Improved
versions use 4 NPN (one extra for the current source and one for the
output buffer/amp). There are also FET versions used in CMOS chips. Some
are very high performance (using FETs). Since none of the devices can
saturate in normal operation they go up to respectable frequencies.

If you can't find a lambda diode circuit on the web I'll find something
and send it to you.

Peter

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