Digital step attenuators (DSAs) are useful in applications where power levels must be adjusted precisely and quickly, such as in cellular communications base stations. Applying its unique silicon-on-insulator (SOI) technology, Peregrine Semiconductor (www. psemi.com) has added to its high-performance line of DSAs with the model PE43204 2-b attenuator that is usable to 3 GHz. The DSA leverages the technology for outstanding linearity and wide dynamic range, along with fast switching speed.

Peregrine's brand of SOI technology is known as UltraCMOS, essentially silicon on sapphire. Ultra- CMOS benefits from all the process refinements that have been developed for CMOS on bulk silicon, and from the existing manufacturing infrastructure that was assembled around silicon, providing the benefits of silicon integrated-circuit (IC) technology, including high manufacturing yields, low power operation and high levels of integration.

The latest addition to the company's line of UltraCMOS DSAs, model PE43204 (see figure), is ideal for emerging wireless applications in third-generation (3G) and fourth-generation (4G) cellular base stations, where it can be used to adjust power levels while maintaining system linearity. The DSA is suitable for use with transmitters, but can also be applied in diversity receive applications where the fast-switching PE43204 can be used to protect the receive path and prevents overdriving the receivechannel analog-to-digital converter (ADC).

The new PE43204 DSA has a frequency range of 50 to 3000 MHz and an attenuation range of 0 to 18 dB in 6-, 12-, or 18-dB steps. The typical attenuation error is +0.1 dB from 50 MHz to around 2000 MHz, with maximum attenuation error of -0.25/+0.40 dB over that frequency range. The typical attenuation error is +0.2 dB from 2000 to 3000 MHz, with maximum attenuation error of -0.10/+0.50 dB over that frequency range. The relative phase is 11 deg. for all attenuation states, and the PE43204 DSA is specified for typical return loss of 15 dB across its operating frequency range. Insertion loss is typically only 0.6 dB and no greater than 0.7 dB. Employing the firm's HaRP technology, the DSA arrives at a new attenuation state with minimal lag time. The switching speed from a 50-percent DC control signal to a 10/90-percent RF level transition is typically only 26 ns. The PE43204 is rated for an input 1-dB compression point of at least +28 dBm and typically +30 dBm. It achieves an input third-order intercept point of typically +61 dBm when tested with two tones spaced 20 MHz apart, each at +18 dBm.

According to Mark Schrepferman, Peregrine Semiconductor's Director of Communication and Industrial Products, "Leading LTE equipment manufacturers turned to Peregrine to solve their gain control needs for a high linearity, fast switching and settling time DSA that is critical to protecting the receive path in LTE base stations."

The PE43204 DSA is biased from a +3-VDC supply and draws typical supply current of 8 A. The DSA features parallel control interface programming logic and is supplied in a 12-lead QFN package measuring 3.0 x 3.0 x 0.85 mm. Evaluation kits are available to qualified customers. P&A: $0.70 each (50,000 qty.); stock. Peregrine Semiconductor Corp., 9380 Carroll Park Dr., San Diego, CA 92121; (858) 731-9400, FAX: (858) 731-9499, e-mail: sales@psemi.com, Internet: www.psemi.com.