High Order Harmonic Oscillators in Microwave and Millimeter-wave ...

3 8th Harmonic Oscillator
duction and the low power consumption. The proposed push-push oscillator adopts the
SEHO concept effectively. The proposed oscillator consists of a microstrip ring resonator,
two same negative resistance circuits and an output circuit. As the output circuit is arranged
inside the microstrip ring resonator, the circuit configuration is also simple. The
fundamental signal and the harmonics are generated by the negative resistance circuits.
The fundamental frequency is determined by the microstrip ring resonator as the common
resonator. According to the push-push principle, the fundamental signal and odd
harmonic signals (f 0 , 3f 0 , 7f 0 ,..., (2n − 1)f 0 ,...) are suppressed in principle and the even
harmonic signals (2f 0 , 4f 0 , 8f 0 ,...,2nf 0 ,...) are enhanced. The desired 8th harmonic signal
is obtained at the output circuit utilizing the resonant modes of the ring resonator. The
undesired even harmonics are suppressed at the output port.
The proposed oscillator is designed and fabricated at the output frequency in V -band.
Two same negative resistance circuits and the microstrip ring resonator are designed at
the fundamental frequency in C-band. In the experiment, the basic operation to enhance
the 8th harmonic signal is demonstrated. The desired 8th harmonic signal is successfully
obtained as the maximum output signal. The design method of the basic push-push
oscillator and the detail development for the 8th harmonic signal oscillator based on the
SEHO is described.
Resonator
Vosc1
Vosc2
N.R. 1 N.R. 2
0@f0
Harmonic resonant field
π@f0
Output circuit
Output (2nf0, n=1, 2, 3, 4,...)
Fig. 3.1: Technical concept of the push-push oscillator based on the SEHO.
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