domingo, 27 de junio de 2010

Silicon RF capacitors set new standard for precision and stability

Using a proprietary semiconductor process, Vishay Intertechnology introduced the industry's first silicon-based surface-mount RF capacitor family. The result was a new standard for high-precision capacitors (HPC) that raised the bar on stability over a broad range of frequencies as compared to conventional capacitors in low profile packages. In addition, the silicon-based surface-mount HPC RF capacitors offered high Q factors, low equivalent series resistor (ESR) values, low parasitic inductance, tight tolerances, and an ultrahigh self-resonant frequency (SFR). Now, the supplier has released a new member of this family in the miniature 0603 case size.

The high-performance, high-precision HPC0603A features SRF values as high as 13 GHz over a broad capacitance range from 3.3 pF to 560 pF. The E12 values available in this range provide extremely stable operation over a wide range of frequencies from 1 MHz to several Gigahertz. Parasitic inductance is a low 0.046 nH. Meanwhile, according to the manufacturer, HPC0603A devices that offer E24 values are scheduled for release in the near future.

In addition, the new capacitor features high Q factors up to 4157, tight tolerances of ±1% or 0.05 pF, and low ESR values. The silicon process guarantees that every capacitor in the production line is within 1% tolerance, said Tony Troianello, marketing manager at Vishay's Integrated Products. Its construction makes it efficient, thus allowing it to handle up to 90 W without any change in the characteristics of the device, added Troianello. The HPC0603A measures 0.063 inches by 0.031 inches [1.60 mm by 0.80 mm] with a 0.022-inch [0.56 mm] height profile. It is rated for a temperature coefficient of capacitance (TCC) of ±30 ppm/°C over an operating range of -55°C to +125°C. Voltage options of 6 V, 10 V, 16 V and 25 V are available.

The HPC0603A's high capacitance range and relatively compact package enable increases in circuit Q, transmission range and reliability. HPC devices' unique construction (see the figure) reduces parasitics by shortening interconnecting traces on PCBs and improves circuit performance by decreasing the distance between components.

This innovative design brings the new capacitor's SRF frequencies to new highs, enhancing performance and transmission/reception quality during operation at high frequencies. As a result, designers of wireless communications devices such as mobile and cordless phones, GPS systems, VCOs, filter and matching networks, RF modules, and base stations can implement HPC devices to reduce product size — simplifying design and reducing the number of components on the PC board — without sacrificing electrical performance.

To predict end performance using simulation programs, a global model for these capacitors has been developed by Modelithics. Integrated with leading EDA tools, the model shows complete characteristics on a variety of PC boards and substrates. It also provides S parameters for these high-precision capacitors.
Samples of the HPC0603A are available, with lead times of up to 10 weeks for production quantities. Typical pricing for U.S. delivery in high-production quantities is $0.082 for 10-pF devices with a ±2% tolerance.


Publicado por: Jahir Alonzo Linares Mora C.I: 19769430 CRF
Bibliografia: http://rfdesign.com/microwave_millimeter_tech/passive_components/radio_silicon_rf_capacitors/

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