Monolithic Multi-mode Wireless Design

Applying innovative design techniques in a 130nm CMOS process, Sirific Wireless has successfully implemented robust direct up/down-conversion architectures in its NEXUS™ family of single-chip RF transceivers for mobile multi-band HEDGE applications.

Sirific has leveraged its expertise in advanced RF CMOS design to optimize performance and resolve design issues associated with direct-conversion architectures. The result is a Digital Direct Conversion receiver and Harmony™, a low-noise direct up-conversion transmitter, both supporting all narrow and wideband modulation types.

Digital Direct Conversion (DDC)

At the heart of Sirific’s DDC Receiver is a unique down-conversion process that implements a patented local oscillator (LO) design and programmable DC offset correction circuitry that removes the effects of any interfering signal. The DDC Receiver implements a 2.5G DigRF-compliant baseband interface that results in increased programmability, smaller size, lower power and faster development times.

Sirific’s high-end HEDGE products, such as NexusRD, take DDC one step further by implementing a dual-receive path to support complete multi-band 3.5G receive diversity. When matched with a dual-antenna radio front end and a baseband processor supporting HSDPA category 9 receive diversity operation, the transceiver can enable downlink data rates up to 10.2 Mbps throughout the cell, twice the average speed of home-based cable and DSL broadband services.

Harmony™-Direct Upconversion Transmitter

The Harmony transmitter utilizes careful frequency planning in a linear architecture which in turn achieves excellent system transmit performance for all standards (HSUPA, WCDMA, EDGE, GPRS, GSM) and frequency bands. In addition, Harmony exhibits very low noise, therefore requiring no external 2.75G transmit RF SAW filters. Both the 3.5G and 2.75G transmitters can interface to industry-standard linear power amplifiers and baseband processors, enabling cost certainty and scale for OEMs and ODMs. Only a one-step calibration is required for NEXUS products that utilize the Harmony transmitter, significantly reducing the time and cost to manufacture.

A multi-mode radio subsystems based on Nexus or NexusRD will fit into a PCB area of 5.3cm² or 6.1cm² and yields a bill of materials with less than 130 and 172 components. These compact radio subsystems make the NEXUS family of chips ideal for mobile handsets, data cards, PDAs and laptops where cost, size, performance and power savings are critical.