RF Active Transmit Mixer is suited for 3G basestations.

Press Release Summary:

Housed in 16-pin, 4 x 4 mm, surface-mount QFP package, LT5521 provides linearity and signal-to-noise performance that allows designers to build compact 3G cellular basestations. It incorporates differential input and output architecture, supporting linearity over operating frequency range of 10 MHz to 3.7 GHz. Able to be used in upconverting or downconverting application, product requires -5 dBm LO signal and has 0.5 dB conversion loss.

Original Press Release:

High Linearity Active Mixer Simplifies Transmitter Design and Reduces Cost of 3G Cellular Basestations

MILPITAS, CA - July 26, 2004 - A new RF active transmit mixer from Linear Technology provides linearity and signal-to-noise performance matching that of passive mixers, allowing designers to build 3G cellular basestations that are more compact and at substantially reduced cost. The LT5521 streamlines basestation design by resolving the high LO (Local Oscillator) drive level, poor LO suppression and low conversion gain issues common to passive solutions. In addition to applications in wideband CDMA, UMTS, GSM, and PHS basestation transmitters, the LT5521's low distortion is ideal for cable downlink infrastructure.

The LT5521 incorporates a differential input and output architecture, supporting superior linearity over a wide operating frequency range from 10MHz to 3.7GHz. It also provides flexible operation in either an upconverting or downconverting application. As a transmit (upconverting) mixer, the input third-order intercept (IIP3) is +24.2dBm at 1950MHz, and the Noise Figure (NF) measures 12.5dB. These two parameters contribute to a high spurious-free dynamic range.

Unlike passive mixers, which require a high LO drive level of as much as +17dBm, the LT5521 needs only a modest -5dBm LO signal. This saves one or two stages of external LO amplifier, resulting in a more compact solution size and lower cost. Moreover, the LT5521 offers substantially reduced local oscillator leakage from the LO to other input and output ports. This solves a major design headache by removing undesirable LO signal from the transmit path. Unlike passive mixers, which typically have high conversion loss in the range of 6 to 10dB, the LT5521 has only 0.5dB loss, contributing to improved signal-to-noise performance. Taken as a whole, these attributes result in a solution that has far fewer external blocks, markedly reduced system costs, and overall improved performance.

The LT5521 operates from either a single 5V or 3.3V supply. The device comes in a 16-pin 4mm x 4mm surface mount QFP package. The price in 1,000 piece quantities is $4.95. The product is available from stock.

Summary of Features: LT5521

Wideband Output Frequency Range to 3.7GHz

+24.2dBm IIP3 at 1.95GHz RF Output

Low LO-RF Leakage: -42dBm

Low LO Drive Level: -5dBm

Single-Ended LO Drive

Wide Single Supply Range: 3.15V to 5.25V

Company Background
Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.

Note: LT, AND LTC are registered trademarks of Linear Technology Corp.

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