AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
Simple delay line based oscillator4/25/2023 In an optoelectronic oscillator, the continuous light of a laser is modulated by a microwave signal and transmitted by a long optical fiber and then applied to a photodetector. 1, benefits from an optical fiber delay-line as the storage element, which determines the oscillation frequency and its phase noise. An optoelectronic oscillator, as shown in Fig. The first optoelectronic oscillator was developed by Yao et al. To overcome the above limitations, optoelectronic oscillators (OEOs) have been introduced to generate high frequency, low phase noise oscillations with high frequency tuning range. As a result, there is a limited tuning frequency range of the resonator where an increase in oscillation frequency and frequency tunability result in phase noise degradation. ![]() These types of resonators have few modes with high Q-factor in certain frequencies. There are various types of resonators including mechanical resonators (such as quartz crystals), electromagnetic resonators (such as dielectric cavities) and acoustic resonators. As a promising approach to attain low phase noise oscillators, high Q-factor resonators are used. However, as a result of low Q-factor cavities, the output signal of the electronic oscillators does not exhibit low phase noise. One relevant group of oscillators is electronic oscillators, where the inductor–capacitor resonators are used. where A and β j ω are transfer functions of amplifier and resonator in the oscillator loop, respectively, ω is oscillation angular frequency and A β j ω is the open loop transfer function of the oscillator. To achieve sustained oscillations in an oscillator the Barkhausen criterion must be satisfied as | A β j ω | = 1 arg A β j ω = 2 n π n = 0, 1, 2, …. ![]() In oscillators, phase noise of output oscillation depends on the energy storage capability of resonators. Some instances are mechanical oscillators (such as pendulum), electromagnetic oscillators (such as electronic and cavity based oscillators), lasers and masers. Oscillators are one of the most widely used components in the present day technology. We also show that the Q-factor of a delay-line based oscillator is proportional to the half of the round-trip time of its delay line while the Q-factor of an oscillator based on a usual resonator is proportional to the energy decay time of its resonator. ![]() We show that the loaded Q-factor of a delay-line cavity is greater than its unloaded Q-factor!, besides we show that the Q-factor of a lossy delay-line cavity is the same as that of the lossless one! (in contrast to the behavior of the usual resonators). Hence, the behavior of the Q-factor of a delay-line based cavity will not be the same as that of the usual resonators. We show that the Q -factor of a delay-line based cavity is a function of its round-trip time that is not equal to the energy decay-time of usual microwave or optical resonators. Theoretical expressions for unloaded and loaded Q-factor of delay-line based cavities and oscillators are derived. In this paper a theoretical derivation of unloaded and loaded Q -factor of delay-line cavities, such as optical fiber delay-lines, and delay-line based oscillators, such as optoelectronic oscillators (OEOs), is presented based on three approaches: (I) second-order resonator approximation, (II) linear time-invariant phase-space model and (III) energy approach.
0 Comments
Read More
Leave a Reply. |