RF oscillators are an important part of most RF signal chains, as they are used as local oscillators (LO) with frequency conversion circuits, reference frequencies, and frequency synthesis generation circuits. The basic purpose of an RF oscillator is to generate periodic and continuous RF signals, usually sine waves, from the input of a DC power supply. All RF sources have some form of oscillator to produce the initial RF signal. This includes clock generators used as digital circuits and converters, such as analog-to-digital converters (ADCs) and digital-to-analog converters (DACs).
There are two main types of RF oscillators, crystal oscillators (XO) and negative resistance (NR) solid-state (SS) oscillators. Crystal oscillators are very common for more than 100 years. The NR-SS oscillator is a recent one and consists of DC-biased SS devices such as a GUNN diode, an Impulse Ionization Avalanche Transfer Time (IMPATT) diode, a resonant tunnel diode (RTD), and a transistor type.
Reference oscillatorSingle-frequency high-fidelity signals can be generated.
100 MHz reference oscillator, internal reference, phase noise -150 dBc Hz, SMA
Lock-in oscillators and voltage-controlled oscillatorsUtilize additional circuitry to enhance its performance.
Temperature-compensated crystal oscillatorEnsure the accuracy of the oscillator signal.
Lock-in oscillatorThis is typically a dielectric resonator oscillator (DRO) with additional circuitry (phase-locked loop) that combines the proximity carrier performance of the reference oscillator with the DRO's good distance away from the carrier noise base. This type of circuit is designed to improve the phase noise of the oscillator output in microwave applications.
50 MHz Phase-Locked Crystal Oscillator, External Reference 10 MHz, Phase Noise -155 dBc Hz, SMA
Voltage-controlled oscillator (VCO).It is an oscillator that can control the output frequency using an input voltage (usually DC voltage). There are many ways to achieve oscillator voltage control, including the use of voltage-controlled capacitors.
Voltage Controlled Oscillator, 5220 MHz 5420 MHz, Output Power -1 dBm, Phase Noise -83 dBc Hz, Tuning Range 05v~4.5v，sma
The following are the key performance parameters of the RF oscillator:
Center Output Frequency (Hz).
Tuning frequency range (Hz).
Reference frequency (Hz).
Reference impedance (ohms).
Output power (dB dBm).
Frequency stability (MHz deg c or ppm).
Power stability (db deg c).
Phase noise (dBC Hz).
Harmonics (DBC) and Second Harmonics (DBC).
Spurious (DBC).
Bias supply voltage (VDC).
Bias Supply current (IDC or MA).
Tuning voltage range (VDC).
Impedance output input (ohms).
Operating temperature. Aging per year (ppm).