Step up the pace on timing products

ESNA Oct15 Pg28 & 29 Dove 1Crystal based timing is by no means new, but in recent years it has seen significant evolution, with developments from familiar players and some disruptive new technologies to boot.

Quite a bit has changed in the frequency control segment since the inception of Dove Electronic Components 32 years ago. Although that seems like a long time, it’s not even a third of the time that quartz crystals, and later oscillators, have been around.

Today quartz crystals and oscillators are used for timing electronic signals in nearly every electronic system. The signal creates a regularly occurring and repeating waveform, or clock pulse, that controls the sequence of operation of the processors and other electronic components on the board.

Understanding specifications

Crystals and oscillators differ primarily in three ways: firstly, with regard to their frequency stability over time; secondly their accuracy, in terms of jitter and phase noise; and thirdly their ageing, which is dictated by the stability of the original frequency over time. They are also defined by how well they maintain these specifications over both voltage and temperature.

These differences, along with package options, combine to create three categories: commodity, precision and high precision, or ultra-precision. The crystal itself is a standalone device that requires other components to make an ‘oscillation circuit.’ An oscillator is a module that includes a crystal and an application specific circuit (ASIC) with said oscillation circuitry. The designer makes the decision of using just the crystal, which is cheaper but requires additional components, or an oscillator module requiring only a voltage to operate, but is more expensive.

Product evolution

Since the great recession ended those frequency control product (FCP) companies that survived have really focused and have released many innovative new products. There are also some new companies with disruptive technologies that have entered the fold. Though they are still going strong, crystals and oscillators have been subject to the same competitive pressures that all electronic components face these days.

According to Dove, Japanese companies Epson, NDK, Kyocera and KDS control four of the top five revenue spots, with Taiwan based TXC rounding out the group. Dove distributes all five of these manufacturers from its East Setauket, New York headquarters, along with over 20 other crystal and oscillator suppliers.

As explained, crystal technology is not new. The use of crystals in electronic systems dates back over 110 years. From this early date, crystals have operated using the same basic principle. When electricity is applied to a quartz crystal it will contract and expand so as to resonate at a certain frequency based upon the size and cut of the crystal itself. The user will determine what frequency output they need to drive as the clock signal for their electronic system. Today, crystal based timing still dominates, with billions of units consumed each year.

Timing innovation

Crystal based timing really had no competition for decades, until about 30 years ago. There are now two technologies trying to move in on the multi-billion piece crystal/oscillator industry.

The first is micro-electronic mechanical systems (MEMS). In the case of MEMS oscillators, the crystal resonator is replaced by a MEMS resonator. In many cases the MEMS resonator itself is more reliable structurally and cheaper to manufacture, however in some applications the purity of signal and overall performance of a true crystal oscillator cannot be matched. Dove names San Jose, California based, SiTime, as the main player in the MEMS oscillator space.

The other technology vying for a piece of the crystal oscillator pie is all silicon oscillators (ASOs). ASOs do not have a resonator element like a crystal oscillator or a MEMs oscillator. In ASOs the frequency generation is achieved solely by the design and functions of the circuit, with no electromechanical process and no moving parts. Based in Austin, Texas, Silicon Labs is said to be one of the leaders in ASOs.

In addition to the above new technologies, many of the manufacturers of crystals and oscillators are now offering configurable crystal oscillators that can be quickly programmed at the factory or at the distributor. Dove, for example, operates a large scale oscillator programming center enabling it to program thousands of oscillators per day. Epson Electronics is Dove’s largest vendor for configurable oscillators, but it can program devices from Abracon, Cardinal Components, Citizen Finedevice, ECS, Fox and SiTime.

As this brief history of timing indicates, there is now more choice than ever for purchasers trying to match their timing requirements with the right frequency control product.