CMEMS programmable oscillators shake quartz crystal oscillators for hundreds of years

Crystal oscillator

Quartz Oscillator 3225 20M OSC

A scientist in Taiwan did an experiment: he invited 50 volunteers to see all the blue objects in the room for 30 seconds. Then ask them to close their eyes and ask them how many red, green and yellow objects they saw. They are all dumbfounded because they only focus on blue objects and not notice objects of other colors.

In fact, similar situations happen almost everywhere in everyone, and we are always habitually neglecting things. The latest example of what happens to electronics engineers is that CMEMS programmable oscillators achieve smaller size, higher reliability, better aging resistance and more with fully integrated, highly reliable CMEMS (CMOS+MEMS) technology. Single-die oscillator solution with high integration and shorter lead times. However, in the market of frequency control and timing products monopolized by quartz crystal (XO) solutions for hundreds of years, engineers' inertial thinking makes it difficult for them to move their eyes from the quartz crystal oscillator (XO) to his small partner CMEMS programmable. Oscillator .

"Now, through our continuous efforts, more and more engineers and manufacturers have accepted the CMEMS clock products. The delivery volume of our CMEMS products is expected to increase significantly this year." SiliconLabs "We are expecting more engineers to understand the unique advantages of CMEMS programmable oscillators , and to be able to shake the quartz crystal oscillator for more than a hundred years," said Steven Zhang, a product manager at China's core distributor.

Evolution of frequency control technology

The $3 billion annual frequency control market has been dominated by quartz crystals and quartz-based oscillators for decades, and almost all types of electronics rely on a small piece of machined quartzite to generate at least one possible operation. frequency. However, there are still many limitations to quartz-based frequency control designs. For example, he needs more specialized and complex production processes, long, variable delivery times (weeks to months).

To overcome these shortcomings of quartz crystals, microelectromechanical systems (MEMS) solutions have evolved over the past five years. MEMS technology originally originated from the pursuit of smaller form factors, and now has other significant advantages, including delivery time, supply stability, product reliability, device size and cost performance, which make MEMS-based oscillators part of the MEMS-based oscillator. Quartz based frequency control market. Figure 1 below shows the evolution of frequency control technology.

Figure 1. Evolution of frequency control technology

Although MEMS resonator technology has solved the basic defects of quartz crystals, it has just entered the highly competitive frequency control market, and it has some shortcomings. First, the MEMS device is smaller than the quartz crystal, so it cannot provide more energy to the oscillation period. This means that the conversion efficiency is low at the same frequency, resulting in poor signal to noise. Second, traditional MEMS materials, such as monocrystalline silicon, polycrystalline silicon, and even polysilicon germanium, exhibit significant drift with temperature, which can lead to signal integrity and thermal hysteresis problems.

In 2010, SiliconLabs acquired a fully integrated, high-reliability CMEMS technology by acquiring a MEMS architecture directly on standard CMOS wafers in a high-volume production by acquiring a company called SiliconClocks. "The dream of integrating high-precision oscillators on standard CMOS chips has been made possible by SiliconLabs and their latest Si50xCMEMS oscillator series," said Steven Zhang.

CMEMS technology is an important technological advancement in the frequency control market. By combining the best features of both MEMS and CMOS, CMEMS programmable oscillators provide the best general purpose oscillator solution for embedded, industrial and consumer electronics applications where cost and power are limited.

Advantages of CMEMS compared to XO

Compared to the traditional quartz crystal oscillator (XO), the Si50xCMEMS programmable oscillator has the following advantages:

1. General purpose oscillators for cost, space and power sensitive applications;

2, custom sample delivery time is less than 2 weeks;

3. Direct replacement of crystal oscillator (XO);

4. Instantly customize the samples at the customer site using the field programmer;

5. High stability and predictable supply chain;

6, with a full temperature range, impact, vibration and other environments, with a high stability frequency output of 10 years;

7. Performance is more reliable than XO in vibration, impact, temperature and aging environments.

Traditional quartz supply chains are complex, costly, and inefficient. Their highly customized manufacturing processes (delivery times of weeks to months) not only increase the management of the supply chain, but also limit the frequency range produced by the reference oscillator. As the data rates of computing, communications, and networking devices increase, this limitation puts more pressure on the synthesis of clocks that provide high quality high frequency clock signals. The CMEMS process stream greatly simplifies the supply chain. Significantly reduced delivery time (less than 2 weeks) and unlimited programmability from kHz to GHz output frequency.

Figure 2. CMEMS custom samples delivered less than 2 weeks

"Better resonators are equivalent to better stability. CMEMS technology ensures that the performance in the data sheet has 10 years of frequency stability, including soldering offset, load pull, VDD variation, operating temperature range, vibration and shock, and guaranteed Operating life performance is 10 times that of other companies' XO and MEMS oscillators," said Steven Zhang.

The Si50x has a highly stable frequency reference over the full temperature range. Traditional MEMS resonators have a frequency drift of -30-40ppm/°C, while CMEMS frequency drifts.

Figure 3. Si50x resistance to quenching and sudden heat change

In addition, the Si50x is a highly stable and reliable oscillator with an atomic mass of less than 61000 times compared to comparable crystals, making it less susceptible to shock, vibration, acceleration and aging.

Si50x is a powerful alternative to traditional XO

Combined with SiliconLabs' mixed-signal expertise, CMEMS technology can generate almost all frequency outputs with a single reference frequency, and the output frequency is as stable as mass-produced crystal oscillators, addressing thermal hysteresis or signal integrity issues, with high shock and Vibration capability and guaranteed stability of ±20ppm frequency over 10 years. The CMEMS single-chip oscillator will be an alternative solution for crystal oscillators.

The Si50xCMEMS oscillator family includes four programmable chips for the industrial, embedded and consumer electronics markets, as shown in Figure 4 below. Each chip can be customized via the web or in the field.

Figure 4. Overview of the Si50xCMEMS Oscillator Series

"Si501/2/3/4 is a universal XO replacement for application needs: low power (1–8mA), low frequency, LVCMOS clock (<100MHz), small size (2.0x2.5mm), low cost ( ~$0.5010KEAU), high reliability (high vibration, high temperature), good consumption / embedded jitter performance (1.1psRMS period jitter) in the system." StevenZhang said.

In addition, for general timing requirements in consumer, embedded and industrial applications, the Si50x is not only an ideal clock source for SoCs, CPLDs, mPs, FPGA digital logic, but also an ideal clock source for consumer/embedded applications in data paths, for example, SAS, SATA, DDR3 and PCIe.

"At present, Shiqiang does not recommend the Si50x for communication applications. Because communication applications usually require low phase jitter (<1psRMS12kHz-20MHz), SiliconLabs crystal oscillators (Si51x, Si53x, Si59x) are more suitable for this application." "But we "The high-speed, low-jitter, higher-frequency output continuation products such as the SI504/5/6/7/8/9 introduced in the second half of this year can meet the needs of many communication clocks," Steven Zhang emphasized.

See Figure 5 below for a comparison of the price of the Si50xCMEMS oscillator with the Si51x, Si59x and Si53x/5x/7xXO. The Si50x family complements SiliconLabs' oscillator product line. The Si501/2/3/4 family targets low cost, low power, general purpose oscillators for the industrial, embedded and consumer markets. SiliconLabs' Si51x/9x/3x targets communications and data transmission applications with high performance and low phase jitter requirements.

Figure 5. Comparison of the price of Si50xCMEMS oscillators with Si51x, Si59x and Si53x/5x/7xXO?

"The Si50x oscillator provides a custom 2 week sample delivery cycle. The world's FAE can also be programmed instantly at the customer's site, using a field programmer for 0 time delay sample delivery. This flexible programmability makes the Si50x family of products The Si50x oscillator is compatible with existing quartz or MEMS oscillator pins and packages for fast and easy replacement solutions," said Steven Zhang.

Figure 6. 0-time sample delivery using a field programmer

Application design example

The Si50x application targets industrial security, variable frequency servos and other applications that require long life, as well as digital cameras, storage and memory, ATMs, POS machines and multifunction printers that require small package crystals. Reliable and efficient for typical target applications, including:

lSoC video application processor (Roku)

L10/100 Fast Ethernet (SoC & NIC / LOM implementation)

lUSB2.0 (480Mbps)

lUSB3.0 (5Gbps)

lDDR3

l industrial security

l communication

l Replace the traditional crystal oscillator as the reference clock of many MCUs

As shown in Figure 7 below, in a 10/100 Fast Ethernet application, the jitter of the Si501EVB is measured in low jitter and low power modes, respectively. The test results show that the Si501 has almost the same random jitter performance as the R&S high-end signal generator in the low-jitter mode. The Si501 has a slightly lower jitter performance in the low-power mode, but still has an acceptable system jitter margin. Therefore, the Si50x is suitable as a 10/100 Fast Ethernet reference clock.

Figure 7. 10/100 Fast Ethernet – Measuring the jitter of the Si501EVB in low jitter and low power modes, respectively

As shown in Figure 8 below, in the USB2.0 application, compared to the quartz crystal oscillator, Si501 low jitter mode and low power mode eye jitter test, all configurations pass the USB2.0 compatibility test, Si501 performance equals Or more than a typical solution, so the Si501 is suitable for use as a reference clock for USB2.0.

Figure 8. USB2.0 compatibility test

Steven Zhang finally pointed out: "Si50x's product positioning is to replace the traditional XO, so his price is also comparable to XO, customers do not have to worry about not being able to afford. So, engineers please don't succumb to the quagmire of their own inertia and can not extricate themselves. Whether you like it or not, CMEMS oscillators are here."