What is the meaning of crystal oscillator ppm?

The crystal oscillator is a crystal oscillator, which refers to cutting a thin plate (referred to as a wafer) from a quartz crystal at a certain azimuth angle, a quartz crystal resonator, which is simply referred to as a quartz crystal or a crystal, a crystal oscillator; and adding an IC to form an oscillation circuit inside the package. The crystal element is called a crystal oscillator. Its products are typically packaged in a metal case and are also available in glass, ceramic or plastic.

Electronic components are a key part of circuit design. The accuracy of the circuit is directly related to the quality of the product using this crystal, but the most important manifestation is that a small parameter is the ppm value of the crystal, that is, the precision capacitance value. The lower the accuracy value, the more accurate and accurate the electronic component is, and the more durable and responsive the effect is. So, do you know the ppm in the crystal circuit? The small parameter of ppm is how to make a big difference.

1:120ppm, 27M crystal oscillator, frequency error = 120/1 million * 27M = 3240Hz

The accuracy of the crystal determines the timing accuracy of the clock.

2: The crystal frequency is 32772.2HZ, the error is +1.2ppm

The one-year error calculation process is:

Δf = +1.2/1 million*32772.2

Δt/sec = Δf/32772.2 = 1.2/1 million

One year error = Δt*24*3600*365 = 37.8 seconds

The main parameters of the crystal oscillator are nominal frequency, aging rate, frequency accuracy, frequency stability, phase noise, power consumption, and so on.

1. Nominal frequency: refers to the nominal output frequency of the crystal oscillator;

2. Frequency accuracy: refers to the difference between the measured crystal frequency and the nominal frequency at normal temperature (25 degrees). This is not very important;

3. Frequency stability: Generally refers to the frequency temperature stability, which refers to the frequency change with temperature in the working temperature range of the crystal oscillator. It is generally indicated by PPM or PPB, 1PPB=0.001PPM=1*10-9;

4, aging rate: as time goes by, the frequency value changes with the size;

5. Phase noise: The ratio of signal power to noise power (C/N) is a technical indicator for characterizing frequency jitter. In general, radar and other equipment have special requirements for phase noise;

6. Another important characteristic of the crystal is the "RR equivalent impedance", and the crystal oscillator appears to stop vibration. The analysis showed that the wafer resistance was greater than 80 ohms.