Performance Advantages with MEMS Oscillators

The expanse of technology has by far exceeded our knowledge and perceptions. The days of slow electronic devices are no longer relevant. Time and again we have been awed by innovative technologies that help us overcome obstacles and reach our goals. Today is an era of speed and dazzling performance. Electronic devices such as digital cameras, gaming systems, tablets, laptops etc., have to be robust and reliable with advanced features that accelerate performance and provide quick accessibility in a cost-effective manner.

 

The simulated games are accompanied with high quality sensors and microphones to provide the customer a real-life experience.  Keeping all these requirements in consideration, those who deal with the design and manufacture of these electronic items have to implement components that incorporate the desired application qualities and provide the customers with a positive experience. Thus, there is great demand for next generation solutions that are feature-rich and provide a lower total solution cost.  When it comes to clocking choices, the newest and most promising technology is MEMS (Micro-Electro-Mechanical Systems) oscillators. MEMS solutions were quickly adopted into the automotive market.  Applications such as tire pressure monitoring systems and air bag sensors benefited from the precision, reliability, and total solution cost.

 

Now the MEMS oscillator is widely used in electronic applications for various computing and electronic purposes such as laptops, DVRs, set top boxes, etc. The MEMS oscillator is revolutionizing the traditional quartz-crystal oscillator as the next generation clock timing solution for a number of reasons, but most importantly because of the superior performance and lower solution cost. It provides optimal performance and flexibility due to its ability to be programmed for any frequency within the range. It provides a simplified and enhanced inventory control and management process for supply chains. It can interface with numerous SoCs and ASSPs and operate under any standard voltage condition.

 

In addition to the performance and cost advantages, the MEMS oscillator offers significantly higher reliability. It features 70kG shock and 50G vibration, which represents a 10-50x improvement compared to a quartz-crystal oscillator.  Furthermore, the MEMS oscillator eliminates any start-up issues and frequency dips that occur with quartz-crystal oscillators.

 

MEMS performance is now meeting the demands of the highest performance telecom and networking systems that could only be addressed with quartz-crystal oscillators in the past.  Specifically, frequency stability as low as 0.1ppb (parts-per-billion) and phase 0.5fs (femto-second) jitter performance, combined with the lower solution cost and improved reliability make the MEMS oscillator an ideal solution for network routers, wireless and wireline telecom infrastructure equipment, and enterprise storage applications.  All of these applications benefit from SiTime's single-ended and differential oscillators

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Top Five Reasons to Replace your Quartz Oscillator

A quartz oscillator (also known as a crystal oscillator) has been the reference clock of choice in the electronics industry for many decades. Recently, this legacy device has been under attack by a host of clock devices that use a newer, more advanced technology – Silicon MEMS. Here are the Top Five reasons why you should replace your quartz oscillator with a Silicon MEMS device.

1. Higher Performance:  
Silicon MEMS oscillators offer higher performance across a wide spectrum of parameters. A quartz oscillator has been optimized for specific parameters – such as phase noise at a particular frequency and operating voltage and does extremely well. Silicon MEMS oscillators not only perform extremely well on these specific parameters – but they also offer high performance other parameters, such as:

a. Stable and reliable startup over temperature (which is an inherent problem in quartz oscillators due to the activity dips of crystals)
b. Full frequency range available at 1.8V, which is not commonly available from quartz devices
c. Oscillator stability as good as 10 PPM, which is not commonly available from quartz devices (MEMS TCXOs offer stability as good as 0.1 PPM)

2. More Features:  
Silicon MEMS oscillators offer many more features than a quartz oscillator.  Some of these features are listed below

a. Any frequency, up to 6 decimal places of accuracy. This capability is useful for generating higher performance or lower error rates from systems.
b. Drive strength control for better impedance matching, ability to drive multiple loads, or reduced EMI.
c. Thinner packages for thinner electronics.
d. Operation at custom voltages between 2.5V and 3.3V.

3. Better availability:
Production lead times of Silicon MEMS oscillators are 3-5 weeks, while that of a quartz oscillator is 6 – 16 weeks. This reduction of lead time ensures that Silicon MEMS oscillators can reduce inventory and cost of ownership.

4. Better robustness and reliability:
Silicon MEMS oscillators are based on Silicon, and use no quartz. They offer 10 times more robustness (ability to withstand shock and vibration) than quartz oscillators, as well as ten times better reliability.

5. Better cost trajectory:
Silicon MEMS oscillators have a better cost trajectory than quartz oscillators because they are based on Silicon and leverage the semiconductor industry infrastructure.

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The Unique Features and Benefits of Silicon MEMS Differential Oscillators

A differential oscillator is used as reference timing sources in very high performance electronic systems. Typically, differential oscillators have a frequency in excess of 100 MHz, though frequencies below that are also occasionally used.

 There are a couple of reasons why differential oscillators are used in electronic systems. First – a differential output eliminates common mode noise, which is important in very high performance, high-speed systems. Another reason for using a differential oscillator is that it offers more robustness against power supply noise – and therefore, offers a higher Power Supply Rejection Ratio (PSRR). These two capabilities are especially useful in serial data protocols that transfer data in excess of 6 Gigabits per second.

 Historically, a differential oscillator is made of a quartz resonator, married to a fixed frequency analog circuit (oscillator). The quartz resonator operates in either fundamental or overtone mode, and generates resonance at the target frequency of oscillation. The clock output from the oscillator goes through output conditioning, and appears as LVPECL, LVDS, CML or HCSL outputs on the device. LVPECL and LVDS are the most popular signaling standards in differential oscillators, with LVDS getting more adoption in the recent past because of its lower power consumption.

 A Silicon MEMS differential oscillator uses a MEMS resonator operating at a fundamental frequency of resonance, which is married to an analog circuit consisting of an oscillator, a PLL and various other functions. Most of the Silicon MEMS differential oscillators are programmable, i.e. their frequencies, voltages, stabilities, output signaling type and control pin can be configured exactly to the customer's specification. Because Silicon MEMS timing companies use the fabless semiconductor model, samples of these customized devices are available in less than a week, and production is available in 3-5 weeks, both of which are very important for accelerating time to revenue.

 Another unique advantage of Silicon MEMS differential oscillators is its ability to offer very high frequencies and stabilities at very low voltages, without resorting to overtone and SAW technology. Therefore, they eliminate the startup issues that are associated with overtone oscillators, and they offer significantly better stability than SAW oscillators, as low as 10 PPM, which is not available from SAW. In addition, their aging is also significantly better than SAW oscillators.

 With all these benefits, it's no wonder that Silicon MEMS differential oscillators are gaining significant traction against quartz oscillators and are replacing the latter in storage, networking and telecom applications.

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Learn more about :- Voltage Controlled Oscillator , TCXO , Crystal Oscillator

What is a Differential Oscillator? Where can it be used in Electronics?

There are two major kinds of electrical signaling –Single-ended (LVTTL, TTL, LVCMOS, CMOS, etc.) and differential (LVDS, LVPECL, HCSL, etc.). Differential signaling makes the use of 2 signals that are exactly opposite in phase to each other, thus eliminating common mode noise and resulting in a higher performance system. Differential signaling is used by many high performance protocols such as SATA, SAS, FibreChannel, 10G Ethernet, etc.

Differential oscillators are usually used to provide higher frequencies in very high performance systems where single-ended clocks do not perform well, such as the examples listed above. Typically, differential oscillators are used at frequencies above 100 MHz, because the rise times of differential clocks are usually much faster, and can support these high frequencies. However, it is not unusual to see differential clocks at even 25 MHz. Differential oscillators can output frequencies as high as 1 GHz.

One of the main reasons why differential oscillators are used in electronic systems is that they offer more robustness against power supply noise (and therefore, a higher PSRR) and reduce common mode noise coupling in the system. This is especially crucial for very high speed circuits, typically above 6 Gigabits per second data rates.

Historically, LVPECL protocols have been very popular in differential signaling. However, recently, LVDSs signaling has started to gain in popularity, driven by the lower power consumption of this protocol.

Since the output frequencies of differential oscillators are very high, they have typically operated at 3.3V and higher voltages. However, newer differential oscillator devices from Silicon MEMS timing companies have offered differential oscillators at voltages as low as 1.8V.

Typical quartz-based differential oscillators are offered in industry standard, 6-pin footprints, either 7x5mm or 5x3.2mm. Silicon MEMS-based differential oscillators also fit in these footprints, ensuring that they can replace differential quartz oscillators with no changes in design or layout. Some newer devices are also available in extremely small, 3.2x2.5mm packages.

Silicon MEMS-based differential oscillators are usually programmable, i.e. their frequency, voltage, stability, drive strength, and other features can be customized exactly to the required specification, which is different than what quartz differential oscillators can achieve. The ability to customize is an extremely important feature that can be useful in a variety of scenarios –such as –reducing EMI, bit error rates, higher performance, higher throughput, etc

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Learn more about :- Voltage Controlled Oscillator, TCXO, MEMS oscillator

MEMS-Based Silicon Oscillator - Features and Benefits

Micro-Electrical Mechanical Systems (MEMS) have been greatly expanding in popularity over the past decade. While the automotive industry found MEMS vital for vehicle safety applications (tire pressure monitoring, air bag sensors, etc), these MEMS components have more recently been put to use in systems including sensors, gyroscopes, and microphones. These systems are used in high end electronics devices like Smartphone's, Digital cameras, tablets, gaming devices, etc.

In the past five years, MEMS-based Silicon oscillators have been replacing quartz oscillators in electronic applications. MEMS-based Silicon oscillators have numerous advantages over quartz including more features, higher performance, faster availability, higher robustness and reliability, along with a lower cost.

MEMS-based Silicon oscillators were first used in consumer electronics in such devices as laptops, DVRs, digital cameras, stereos, etc. But since SiTime has recently released a much higher performance MEMS–based Silicon Oscillator, these devices are being used in high performance applications like:

Telecom infrastructure – highly stable MEMS-based Silicon Oscillators, such as MEMS TCXOs (Temperature Compensated Oscillator) have been designed in by companies developing core routers based on SONET and Synchronous Ethernet and optical networking systems.

Differential MEMS-based Silicon oscillators have also replaced high frequency SAW (Surface Acoustic Wave) crystal oscillators, leading to their usage in Storage Area Networks and RAID systems based on SATA, SAS and FibreChannel protocols.

MEMS-based Silicon Voltage Controlled Oscillators provides a level of pullability and precision-tuning that is crucial in synchronization of clock signals. This leads to wireless applications, such as cell-phone base-stations and repeaters to start adopting the usage of differential and single-ended MEMS-based Silicon oscillators, which are well-known for their robustness, reliability, and low phase noise.

The addition of programmable signaling levels makes customizing your oscillator for any product or application easy. Available signaling levels include LVPECL, LVDS, CML, HCSL, or LVCMOS on various Silicon oscillator devices. Frequency is another customizable feature to enhance your system performance. Operating voltage is also a programmable feature, with options of 1.8V, 2.5V, 2.8V, and 3.3V, allowing interface with a wide variety of SOCs and ASSPs.

The long lead time for crystal oscillators is another disadvantage in which Silicon Oscillators have a solution. Lead times of 3-5 weeks enables better inventory control/ management, flexibility in meeting upsides, and simplified supply chain.

Because of a superb frequency stability, as low as 10PPM, the system timing margin and reliability of your electronics will increase greatly. Better stability also offers improved immunity against low frequency environmental noise from power lines, fluorescent lights and transformers.

With a robustness and reliability as high as 50,000 G of shock resistance, 70 G of vibration resistance, and 500 million hours of mean time between failure, MEMS-based Silicon oscillators are 10 times more reliable than quartz.

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Voltage Controlled Oscillator - Usage of Voltage Controlled Oscillators

A voltage controlled oscillator is a timing component that allows the fine tuning of a clock frequency within an electronic system, thus allowing a receiving system to be synchronized with a transmitting system that is not at the same location. The fine-tuning (pulling) of the output frequency can be controlled with an analog voltage input that is offered on one of the pins. Voltage controlled oscillators (VCXO) are generally made of quartz crystals, though recently, all silicon oscillators that utilize MEMS technology have also begun to offer VCXO devices.

Today's programmable and MEMS-based Voltage Controlled MEMS Oscillator that are flexible and provide innovative solutions for various applications such as telecom clock synchronization, wireless networking, FPGA-based systems, instrumentation, audio and video. Two main categories of Voltage Controlled Oscillators are the Differential VCXO and High Performance LVCMOS VCXO. The salient features and benefits are listed below-

Differential VCXO

* 100% compatible with quartz crystal VCXOs

* Provide a differential clock output, at LVPECL, LVDS and other popular signaling levels.

* Excellent jitter and frequency stability allows designers to resolve timing margin concerns and increase system reliability. Increased timing margin translates into fewer system errors and higher long-term reliability

* Programmable differential VCXOs are easily customization and can be optimized for the system application for the best system performance.

* Extremely short lead times (3-5 weeks for production volumes) minimize inventory overhead and reduce cost

* Better availability reduces shortage risk.

High Performance VCXO

* LVCMOS signaling levels, with frequencies up to 220 MHz

* 100% drop in replacement for quartz crystal VCXOs.

* Excellent jitter and frequency stability allows designers to resolve timing margin concerns and increase system reliability. Increased timing margin translates into fewer system errors and higher long-term reliability

* Programmable high performance VCXOs are easily customization and can be optimized for the system application for the best system performance. Best linearity results in simpler loop monitoring in software controlled system PLL

* More reliable PLL bandwidth over operating range

* Quicker lock time and calibration

* Decrease in of modulation harmonics

* Tighter PLL bandwidth and simpler system design

Voltage controlled oscillators have a number of uses, for instance in clock functions to control computer processes. They are also used to give out electronic signals in stationary as well as wireless devices like radio receivers, radio transmitters, routers, modems, game consoles and television. In addition to that, it can be also located on function generators and electronic jamming equipment.

 

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Learn more about :- Silicon Oscillator