Fujitsu Reduces EMI with New Spread Spectrum Clock Generators

3/12/2004 - A new series of spread spectrum clock generators (SSCGs) from Fujitsu Microelectronics America, Inc. (FMA) reduces Electro Magnetic Interference (EMI) that results from higher frequency operation and increased IC integration.

The MB88150 series includes a variety of SSCGs that modulate clock frequencies to attenuate peak emissions in computers, printers, MP3 players, cell phones and other products that operate at increasingly higher frequencies. Peak radiation noise is reduced by slightly modulating oscillation frequencies with the internal modulator. The SSCGs can be used independently or in conjunction with shields, capacitors and chip coils, to reduce the EMI that is observed both at main clock frequencies and at harmonic spurious frequencies.

"New generations of computer and consumer products are being built with highly integrated devices, and they are operating at higher frequencies. Both factors increase the risk of performance problems that arise from EMI noise," said Keith Horn, vice president of marketing for FMA. "Fujitsu's spread spectrum clock generators exhibit excellent noise reduction at the main frequency and also at higher frequencies, and they have been designed to be very cost-effective and space-efficient."

Various Versions Feature Different Frequencies, Modulation Rates
The new SSCG devices are the MB88151, MB88152, MB88153 and MB88154.

The MB88151 has a built-in frequency multiplier and is capable of providing an output frequency of 8.3 MHz up to 133.4 MHz, with modulation rates of 0.5 percent and 1.5 percent for center spread and -1.0 percent and -3.0 percent for down spread.

The MB88152 and MB88153, each of which features a power-down pin and external clock input, provide input and output frequencies of 20 MHz to 134 MHz, with modulation rates of +/-0.5 percent or +/-1.5 percent for the center spread, and -1.0 percent or -3.0 percent for the down spread.

The MB88154 provides a reference clock output, and input and output frequencies of 20 MHz to 67 MHz, with modulation rates of +/-0.5 percent, +/-1.0 percent or +/-1.5 percent for the center spread, and -1.0 percent, -2.0 percent or -3.0 percent for the down spread.

"This new series uses digital PLL circuit technology permitting extremely precise frequency modulation. By controlling the clock frequency modulation with such high precision, the series enables a record 19dB reduction in EMI noise," said Stephanos Thomopoulos, marketing manager, wireless products and ASSPs for FMA. "This new low-noise design eliminates the need for additional EMI noise-reduction components used in conventional clock generators."

Pricing and Availability
All the new SSCGs are manufactured using Fujitsu's advanced CMOS process, feature a supply current of 5mA at 24 MHz, and require power supply voltages of 3.3V. All are available in 8-pin small outline (SO) packages. Pricing starts at $1.29 each in 1,000-unit quantities.

About Fujitsu Microelectronics America
Fujitsu Microelectronics America, Inc. (FMA) leads the industry in innovation. FMA provides high-quality, reliable semiconductor products and services for the networking, communications, automotive, security and other markets throughout North and South America. For product information, visit the company web site at

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