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

1 Introduction
presented [6]. An 8th harmonic push-push oscillator, an octa-push oscillator, and a Gunn
diode harmonic oscillator are described in chapter 3 and 4 as the basic oscillator principle.
The 8th harmonic oscillators in chapter 3 are developed to achieve the highest order
harmonic oscillator using FETs. The phase noise is important evaluation for the oscillator.
Low phase noise is required all the wireless systems. To improve the phase noise of the
8th harmonic push-push oscillator, the octa-push oscillator is proposed. Due to the multi
active device, lower phase noise can be obtained.
In chapter 4, a second harmonic Gunn diode oscillator based on the SEHO is described.
The Gunn devices generally have low phase noise characteristics compared to the FETs.
The RF impedance characteristic is different with the transistor devices. The Gunn diode
harmonic oscillator principle can also extend for high order harmonic oscillator as well as
the 8th harmonic oscillators.
A push-push VCO and a coupled oscillator array in chapter 5 and 6 are the application
of the SEHO. The push-push VCO in chapter 5 is developed to apply the practical wireless
system. In the push-push VCO, the electromagnetic resonant field is intentionally varied
by the variable capacitors to control the resonant frequency. The coupled oscillator array
using the SEHO in chapter 6 is developed for the radar applications. Using the advantage
of the SEHO, the mutual synchronization and the phase control between adjoining
oscillator is demonstrated.
1.4 Constitution of this Dissertation
The SEHO in microwave and millimeter-wave band is proposed and demonstrated.
Chapter 2 describes the basic theory of the oscillator. In the following chapters, the 8th
harmonic oscillator, the Gunn diode harmonic oscillator, the push-push VCO are proposed
as the basic oscillators based on the SEHO concept. Finally, the coupled oscillator array
is presented for the application of the proposed oscillators.
In chapter 2, the feedback oscillator which is the basic theory of the oscillator and
the negative resistance oscillator which is well used in the high frequency oscillator are
explained. Next, the theory of the phase noise which is most important evaluation in the
oscillator is explained. Then, the principle of the push-push oscillator and the simplified
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