ESD-protected Darlington RF gain blocks eschew matching networks

Milpitas, Calif—Chip maker Intersil Corp . is rolling out six RF amplifiers in its ISL550xx family. These devices are slated for use in satellite receivers and ISM band (industrial, scientific and medical) applications. All are packaged in 6-pin SC70 packages. All are 3.3-V devices.

Perhaps best of all, all you need to implement these devices in your circuits are input and output coupling caps. As you can see from the typical schematic (above), no matching networks are required.

These chips should fill the bill for LNB and LNB-T (low noise block) line amplifiers , or as gain blocks in IF strips in satellite HDTV set-top boxes, or even as PA (power amplifier) drivers.

Integrated ESD Protection

Significantly, Intersil's devices pack integrated ESD (electrostatic discharge) protection (up to 3-kV using a human body model). Moreover, Intersil claims its devices tout superior ESD ratings compared to competitors.

The company says its ISL5500xx wares provide “significant cost savings” by reducing the need for external ESD protection.

The table shows a list of released devices.

The ISL55005 is a 3.3-V gain block for operation over the 900-MHz to 2.5-GHz range. The device provides 17-dB of gain and an OIP3 (output third-order intercept point) of 18-dBm. Noise figure is 3.6-dB.

The ISL55005 has an input impedance of 75-ohms and an output impedance of 50-ohms, eliminating the need for the system designer to do an impedance translation. The devices also come in 50-ohm/50-ohm, 75-ohm/75-ohm input/output impedance configurations.


All of the devices in the ISL550xx family are self-biased. Gain is also constant to within 1-dB across 1-GHz of bandwidth.

All ISL550xx devices draw very little quiescent current, too. The ISL55005, ISL55007 , and ISL55008 draw about 20-mA each. The ISL55009, ISL550010 and ISL550011 devices draw 13-mA. All use internal Darlington configurations.

Price And Availability

The ISL55005, ISL55007, ISL55008, ISL55009, ISL55010 and ISL55011 are available now, priced at about 65-cents each in 1,000-unit quantities.

More information on these products, and related others, is available by clicking here.

Click here to select datasheets for these devices (in Adobe Acrobat .PDF formats).

For more details, contact Intersil Corp., 1001 Murphy Ranch Road, Milpitas, Calif. 95035. Phone: 408-432-8888. Fax: 408-432-0640.

Intersil , 408-432-8888,

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