Design considerations of high-efficiency GaAs IMPATT diodes

The efficiency and noise of p
⁺
n
1
n
2
n
⁺
GaAs IMPATT diodes have been studied as functions of the doping ratio n
1
/n
2
(when n
1
=n
2
we have a conventional abrupt p-n junction). For n
1
/n
2
>1 there are tradeoffs between efficiency and noise. At 12 GHz, for example, with a ratio of 4 the efficiency is 25 percent and the noise measure is 3 dB higher then that of a conventional IMPATT diode.