SiGe IQ modulator supports systems up to 4GHz

A high-performance, low-noise in-phase quadrature (IQ) modulator supports radio frequency transmissions up to 4GHz in wireless infrastructure equipment.

Texas Instruments has released a high-performance, low-noise in-phase quadrature (IQ) modulator supporting radio frequency (RF) transmissions up to 4GHz in wireless infrastructure equipment.

The new TRF3703 modulator supports third-generation (3G) CDMA and GSM wireless telephone networks, as well as WiMAX (802.16e) metropolitan-area data networks (MANs).

With a seamless interface to TI's high-speed DAC5687 digital-to-analogue convertor (DAC), the new quadrature modulator provides manufacturers of wireless infrastructure equipment an affordable means to directly convert baseband or intermediate frequency (IF) signals to RF transmission levels, thereby reducing the bill of materials, space and power consumption, while offering faster development times and manufacturing cost savings.

"The TRF3703 quadrature modulator demonstrates TI's ability to provide best-in-class technology for WiMAX infrastructure equipment, just as we have for wireless 2G and 3G infrastructures", said David Briggs, Manager for TI's Wireless Infrastructure Business Unit.

"TI's intent is to drive this emerging market by providing the most complete infrastructure signal chain, enabling manufacturers to develop more complete, flexible end equipments that reduce the overall total cost of ownership for service providers".

The TRF3703 builds on TI's success with earlier quadrature modulators and other signal-chain devices, adding ultra-low-noise and high-frequency RF transmission modulation to TI's comprehensive line of analogue and digital products for wireless infrastructure.

The device is capable of accepting modulated input signals ranging from zero (DC) to 350MHz, then providing RF output modulation from 400MHz up to 4GHz.

This broad range of input-to-output levels allows the modulator to support direct conversion in equipment devoted to a wide range of transmission standards.

Implemented using TI's advanced silicon-germanium (SiGe) manufacturing process, the next-generation TRF3703 offers performance characteristics over a wide frequency range that are ahead of anything available in comparable products.

A low noise floor of -164dBm/Hz and an outstanding linearity of 25dBm for the third order intercept point (OIP3) help in eliminating (reducing) the need for additional filtering.

The adjacent channel power ratio (ACPR) is 77dBc for -11dBm single-carrier WCDMA transmission, helping to ensure the clear separation of channels.

The TRF3703 is a key element in TI's strategy to provide cost-effective solutions for the complete wireless signal chain.

TI has been a leading-edge supplier of technology for wireless infrastructure applications for over 10 years, and is the only company today that supplies a complete analogue and digital solution for the entire WiMAX infrastructure signal chain.

analogue solutions from TI include data convertors, RF chipsets and op amps, as well as reference designs to help speed development.

TI's TMS320TCI6482 programmable digital signal processor (DSP), operating at speeds up to 1GHz, is capable of handling multiple 3G air interface standards and a range of basestation form factors on a single chip.

The TCI6482 DSP's unique combination of high performance and power efficiency provides infrastructure OEMs with a platform to upgrade current systems easily and expand product portfolios efficiently.

The TRF3703 quadrature modulator interfaces to a variety of DACs for flexibility in RF transmitter design.

With a seamless interface to TI's high-performance DAC5687 convertor, the modulator provides a complete, easily implemented solution for direct up-conversion.

The low-noise DAC5687 saves on external implementation by integrating phase, gain and offset adjustment features for interfacing to quadrature modulators.

The TRF3703-DAC5687 combined solution replaces two RF up-conversion stages, saving mixers, buffer amps, local oscillators and RF filters.

Transmitters designed using this architectural combination save space, power, components and cost compared with heterodyne solutions.

Operating from a single 5V supply, the TRF3703 modulator is implemented as a double-balanced mixer.

The RF output block consists of a differential to single-ended convertor and an RF amplifier that is capable of driving a single-ended 50ohm load without any external components.

Output compression of 10dBm, unadjusted carrier leakage of -40dBm (at 2GHz) and unadjusted sideband suppression of -40dBc (at 2GHz) all serve to keep signal quality high and simplify design.

The TRF3703 quadrature modulator is sampling now, with volume production scheduled for Q2 2006.

The device is packaged in a space-saving 4 x 4mm 24-pin QFN (quad flatpack no-lead) package.

Pricing is planned at $7 per unit in quantities of 1000 units.

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