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IQ modulator delivers improved linearity

Posted: 25 Aug 2008     Print Version  Bookmark and Share

Keywords:ultra low noise  quadrature modulator  RF output transmission  4GHz 

Texas Instruments Inc. has introduced a high-linearity, ultra low noise quadrature (IQ) modulator that delivers RF output transmission up to 4GHz, allowing service providers to easily support multiple wireless communications standards on a single RF transceiver card.

TI's TRF370317 IQ modulator is a direct launch RF transmitter device that offers basestation equipment manufacturers improved linearity and higher output power, which can improve overall transmitter performance, while reducing power consumption and operating expenditures for service providers.

The TRF370317 is a high-performance IQ modulator that meets the stringent requirements of GSM, CDMA2000, TD-SCDMA, W-CDMA, and WiMAX, as well as emerging next-generation wireless standards such as LTE and multi-carrier GSM. The TRF370317 enables conversion from base band or intermediate frequency directly to RF frequencies, thereby reducing BOM costs and board space.

"The improved linearity performance of the TRF370317 IQ modulator allows manufacturers to deploy pico, micro or macro basestations, targeting a variety of wireless air interfaces for multi-carrier applications," said David Briggs, general manager of TI's RF and digital radio products. "The state-of-the-art linearity performance of the TRF370317 modulator is consistent across a broad frequency range so that it can be used across multiple customer platforms targeting various communications standards. The TRF370317 is a suitable solution for basestation manufacturers looking to reduce the capital and operating expenditures of their service provider customers while meeting all transmission performance requirements."

The device has an ultra low noise floor of -163dBm/Hz and features an output third order intercept point (OIP3) of 26.5dBm, which improves the adjacent channel power ratio in cellular basestation transmitter designs. It offers up to 4.5dB better OIP3 than its nearest competitor. The device is capable of accepting input signals that range from zero (DC) to 350MHz and generating a modulated RF output from 400MHz up to 4GHz. This broad range of input and output frequencies can offer designers utmost flexibility and support for a wide range of communications standards.

The device can easily interface with a variety of DAC devices, allowing for flexibility in RF transmitter design. When coupled with TI's DAC5688, a 16bit, 800MSps dual interpolating DAC, the TRF370317 provides a highly linear, compact solution for multi-carrier implementations. The low-noise DAC5688 further simplifies implementation by integrating phase, gain and DC offset adjustments for performance optimisation. RF transmitters designed using this direct launch architecture save space, power, BOM components and cost when compared to superheterodyne transmitter implementations.

The TRF3703 family now includes the TRF370317 as well as previous members, the TRF370315 and the TRF370333. Operating from a single 5-volt supply, the TRF370317 modulator is capable of driving a single-ended 50Ω load without any external matching components. Output compression of 12dBm, unadjusted carrier leakage of -40dBm (at 2GHz) and unadjusted sideband suppression of -50dBc (at 2GHz) all serve to keep signal quality high and simplify transmitter design.

The TRF370317 modulator adds to TI's high-performance analogue product line targeted at wireless infrastructure applications including: high performance RF, data converters, clock distribution and amplifier solutions. TI's TMS320TCI6484 DSP is a 65nm, single-core 1GHz DSP that delivers improved data throughput and reduces latency for Beyond3G cellular infrastructure applications. The TRF370317 quadrature modulator is available now in full production and is priced at Rs.229.29 ($5.35) per 1,000 units. A complete evaluation module, the TRF3703-17EVM and data sheet are available

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