Electronic Design

Chipset Enables WCDMA/UMTS Access Points And Gateways

The movement to adopt home basestations known as femtocells to improve cell-phone operation indoors is well underway. Operators are beginning to distribute them, but mostly the activity has involved lots of field tests. The market is expected to expand greatly in the next few years. Femtocell makers are now looking for ways to adopt the latest technology and to cut costs. Maxim Integrated Products offers a femto chipset that fits that goal.

The chipset consists of the MAX2557 receiver and MAX2597 transmitter. The chips implement standard WCDMA in Bands II and V and provide a complete RF-to-bit solution for residential gateways and access points. They incorporate Maxim’s MAX-PHY interface, which eliminates the cost associated with a mixed-signal analog front end.

The MAX2557 receiver is a direct-conversion design with four low-noise amplifiers (LNAs) that monitor the GSM and WCDMA traffic of the macro network. The receiver contains a fractional-N synthesizer and the analog-to-digital converters (ADCs) for the I/Q signal chains. The outputs are low-voltage differential signaling (LVDS).

The MAX2597 transmitter is also a direct-conversion design with fractional-N synthesizer. Variable-gain RF and baseband amplifiers, baseband filters, and I/Q digital-to-analog converters (DACs) are included. A +19-dBm power amplifier is on-chip to save bill of materials (BOM) costs and space.

The MAX2557 comes in a 7- by 7-mm, 48-pin flip-chip land-grid array (fcLGA) package. The MAX2597 transmitter is housed in a 9- by 9-mm, 64-pin fcLGA package. Reference designs and development kits are available (see the figure).

Maxim Integrated Products

www.maxim-ic.com

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