Low-phase-noise oscillator with a microstrip resonator

An oscillator for generating a target signal with a predetermined frequency comprising:

• an oscillating circuit for generating a plurality of signals with different frequencies;
• and
• a first resonator comprising:
• an input port connected to an output port of the oscillating circuit;
• an output port for outputting the target signal;
• a circuit board comprising a metal membrane which functions as a ground layer for providing a reference voltage;
• a first microstrip line with a first predetermined length being positioned on the circuit board and coupling with the metal membrane for forming a first transmission line structure, the first microstrip line comprising a first terminal and a second terminal, the first terminal connected to the input port of the first resonator, the predetermined frequency of the target signal being determined according to the first predetermined length;
• and
• a second microstrip line with a second predetermined length being positioned on the circuit board and coupling with the metal layer of the circuit board for forming a second transmission line structure, the second microstrip line comprising a first terminal and a second terminal;
• wherein the first and second microstrip lines are conductive bars, the first microstrip line is parallel with the second microstrip line without being connected to the second microstrip line between the corresponding first and second terminals of the first and second microstrip lines, either the second terminal of the first microstrip line or the second terminal of the second microstrip line is connected to the output port of the first resonator, and when the oscillating circuit generates signals with different frequencies to the input port of the first resonator, a signal with the predetermined frequency is outputted from the output port of the first resonator to be the target signal through an electromagnetic coupling between the first and second microstrip lines of the first resonator.