A tunnel diode is a low power high frequency negative resistance device.
They were used at a time in the late 50s and early 60s before silicon planar
devices became readily availably to produce oscillations between a few 100
MHz and 1GHz, at this time it was difficult to get stable oscillation from a
BJT transistor above a few 10 of MHz. Those devices that would were very
unreliable alloy diffused Mesa structures. Even then the highest oscillation
frequency were around 150MHz. The tunnel diode though not trivial was a
much simpler structure I believe (I never made any :-)) ) I suspect you
would not just replace the device, but that block of the circuit with a BJT
oscillator. The onset of cheap planar structure transistors of higher and
higher cut-off frequency made them obsolete.
Alan G3NYK
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----- Original Message -----
From: "br4av01" <br4av01@...>
To: <hp_agilent_equipment@...>
Sent: Monday, September 05, 2011 5:31 PM
Subject: [hp_agilent_equipment] Tunnel Diode Questions
It is obvious that HP and Tektronix designers had a great fondness for the
tunnel diode. You can find them incorporated into lots of scopes and other
test equipment. Now that tunnel diodes are not produced, I wanted to ask
what design approaches make this device no longer necessary. The recently
discussed 3310b generator uses tunnel diodes in the triangle generation
stage to compensate triangle + and - current sources as frequency is
increased. What design modifications (staying in the analog realm) could be
used to accomplish the same thing with currently available devices. Are PIN
diodes of any use for these purposes?
Thanks!
-br4
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