Double-drift-region (p+pnn+) avalanche diode oscillators

The advantages of a double-drift-region avalanche diode oscillator are discussed. Conventional structures (p
⁺
nn
⁺
or n
⁺
pp
⁺
) are essentially single-drift-region devices in that transit-time delay (for IMPATT mode) and zone transit (for TRAPATT mode) occur in a single region of one impurity type. The proposed structure (p
⁺
pnn
⁺
) has two drift regions and is essentially two complementary avalanche diode oscillators in series.