Crystal Oscillator VS MEMS Oscillator

We know that according to the material of the oscillator, there’s Quartz crystal oscillator and MEMS oscillator. Quartz crystal has been in existence for more than half a century, has been occupying the vast majority of the clock frequency market.Quartz crystal is divided into active and passive two series, from the usage, the vast majority of electronics products are low-cost passive crystal, that is crystal unit, mean the passive crystal more widely used.MEMS has become a craze with the iphone. We focus on the objective comparative analysis of the MEMS oscillator and crystal oscillator to know their characteristics.

In principle, MEMS oscillator is composed of an all-silicon MEMS resonator (similar to a passive quartz resonator) and a programmable Analog CMOS driver chip. Quartz Crystal Oscillator which is also composed of a quartz crystal and an IC.

A MEMS oscillator can output many frequencies with one base frequency, and a quartz crystal oscillator is the stable frequency, which is an important convenience of  MEMS oscillators, crystal oscillation process is more complex than MEMS. MEMS uses programmable CMOS chips, so the output can only be square wave ,but compared this, Crystal oscillator is more optional. MEMS is more economy in the materials and package size but there’s other question.

Below five parameters which are critical for the design of communications, industrial, and consumer electronic devices, especially the Phase jitter is high required in the communication.

 1) Phase noise, phase jitter

 2) Power consumption

 3) Oscillator start up

 4) Frequency temperature characteristics

 5) Frequency stability

Measurements of the frequency stability of each oscillator are shown below. These results are measured at 3.3V and 25 °C for a time of 50 seconds.

Let’s compare a test result :

The “standard” MEMS oscillator, MEMS has frequency jumps  in wireless standards. The “low-jitter” MEMS oscillator, MEMS, has better performance.

Engineer knows the wearable are designed around a low power MCU. a sample for reference:

An active and standby compared:

The MEMS is more excellent in the lowering power system. The mechanical reliability, the MEMS has not broken, according to the MEMS product structure characteristic, this aspect reliability is very good. Because of the programmable design of MEMS oscillator, different frequency requirements are very simple, any frequency can be achieved by any software frequency multiplication. MEMS products can be quickly burned on demand. This enables rapid delivery.

The lack of frequency jumps qualifies Quartz crystal oscillators for a wide variety of communications standards. MEMS is more lowering system power and saving PCB real estate.

We can conclude that difference industry required different parameter. just according to the application and end user requirement.