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Mobius Microsystems
July 2009

How to Reduce EMI and Improve RF Noise Coupling

EMI is caused by fast changing currents inside the electronic device.  These currents usually come from the clock sources, data and address buses, and other switching signals.  Higher frequency signals get emitted into the air more effectively, and therefore higher order harmonics are usually the main sources of EMI.  Engineers traditionally spend significant effort minimizing EMI in their designs in order to achieve compliancy certification and reduce the RF interference.  This task is further complicated as each new design generation demands increased wireless capability, and operates at higher clock frequencies to meet the bandwidth requirements of today’s multimedia-rich applications. [read more]

Electronic Products
February 2009

Trends in CMOS frequency sources for wireless apps
 

There have been many changes in the electronics industry since the digital revolution began over 60 years ago, but one thing has remained constant until recently: the reliance on crystal and ceramic frequency references to synchronize data transfers within and between virtually every electronic system. Recent years, however, have seen significant innovation in this multi-billion-dollar market, including new technologies like microelectromechanical (MEMS) oscillators, precision piezoelectric resonators, and monolithic standard CMOS devices. [read more]

GSA Forum
December 2008

The Current State of Innovation in Frequency Generation Electronics
 

With all the technical revolution that has taken place in the electronics industry, there are still components that have remained untouched by the far-reaching effects of functional integration: crystal and ceramic frequency references. These components are crucial to almost every electronic system – from garage door openers to satellite receivers. They form the primary building block of data transmission systems by synchronizing data transfers between hosts and receiver ICs. [read more]

As reprinted from GSA Forum, Volume 15, No.4, December 2008." For a high-resolution PDF reprint with the cover, please contact Monica Dominguez at mdominguez@gsaglobal.org for purchase details.

ECNAsia. ECNKorea,
ECNTaiwan
November 2008

Cost-effective replacement for quartz crystals
  Imagine a design engineer whose product requires an ultra-thin form factor and an injection-molded plastic casing. The package height and reliability of traditional, low-cost crystals may be a concern in the mechanical design of that system. Suppose that design needs to incorporate high-speed, high-bandwidth interface protocols in order to transmit and receive data at multiple gigabit/s speeds with acceptable bit error rates (BER), the PHY circuit needs to generate the required GHz frequencies by multiplying its native crystal frequency. It must do so without degrading the phase noise of this reference frequency signal. In such cases, higher frequency references are needed to reduce phase noise. Unfortunately, high frequency crystals are more costly to manufacture than fundamental mode (<50MHz) crystals. [read more(ECNAsia)] [ECNKorea] [ECNTaiwan]

Microwaves & RF
August 2007

CMOS Clock Approach Breaks Quartz Tradition
  This technology provides accurate frequency generation entirely in standard CMOS, a task formerly accomplished exclusively with quartz resonators and crystal oscillators. Clock generation generally evokes images of quartz crystals and quartz-crystal oscillators. The technology has existed since before World War II and has provided reliable reference signals in communications systems around the world. If ever a technology could be considered "disruptive," it would be the one that displaced or at least provided an alternative to quartz crystals for this task. As will be shown, that technology exists and is based on the fabrication of reference signal sources entirely with silicon CMOS technology, forming a line of signal generators called CMOS Harmonic Oscillators (CHO™) [read more]
Planet Analog
January 2007

Basics of Selecting the Optimal Frequency Source For an Application -
Part 1 & 2
  This article analyzes various frequency sources available to the design engineer, from both technical and business perspectives, with the goal of helping select the right frequency source to meet specific system requirements. Because they are by far the most popular, this article will examine quartz-based crystal oscillators in particular, and describe their applications, advantages and disadvantages. Given the rapid growth of consumer electronics, some limitations of quartz crystals have become more pronounced. The article also reviews several recently proposed alternatives to quartz crystals and describes their key properties, such as ceramic resonators and CMOS resonators.  [read more]