Linear Technology Introduces Breakthrough RF to Digital Micro Module (uModule?) Receiver

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MILPITAS (Linear Technology Corporation) has launched two groundbreaking RF digital micromodule (uModuleâ„¢) receivers, the LTM9004 and LTM9005. These devices integrate essential components of 3G and 4G base station receivers (such as WCDMA, TD-SCDMA, LTE), as well as smart antenna WiMAX base stations. By combining RF mixer/demodulator, amplifier, passive filtering, and a 14-bit, 125Msps ADC into a compact, easy-to-use package, these micromodule receivers significantly reduce board space and simplify system design.

The LTM9004 employs a direct conversion architecture with an I/Q demodulator, low pass filter, and two ADCs, while the LTM9005 uses an IF sampling architecture with a downconverting mixer, SAW filter, and single ADC. This high level of integration enables smaller form factors or higher channel density, addressing challenges like signal separation and path selection. It also cuts down on design and debugging time, offering years of proven signal link expertise in a 22mm x 15mm μModule package.

As cellular providers face pressure to reduce capital (CAPEX) and operational (OPEX) costs, there's a growing need for smaller, lighter, and lower-power base stations—like remote radio heads (RRH)—as well as high-density macrocell systems and small digital repeaters. The LTM9004 and LTM9005 directly address these trends by requiring only 25% of the board space compared to discrete designs. This not only saves space but also eliminates the need for developers to optimize dozens of high-frequency components, reducing development time, cost, and time-to-market.

Two main receiver architectures are used in base station designs: direct conversion and IF sampling. Direct conversion demodulates and downconverts the RF signal to DC (0 MHz), simplifying filtering with a 10MHz low-pass filter (for 20MHz signal bandwidth). The LTM9004 implements this approach, with additional filter options available for different bandwidths. IF sampling, used in the LTM9005, downconverts the RF signal to an intermediate frequency (140 MHz) and demodulates it digitally. A SAW filter is integrated for 20MHz signal filtering, with other bandwidth options also supported.

The LTM9004 and LTM9005 come in a space-saving 22mm x 15mm LGA package, using a multi-layer substrate to isolate sensitive analog signals from digital traces, minimizing interference. Power supply and reference bypass capacitors are built-in, ensuring better performance, cost efficiency, and space savings compared to traditional packages.

Samples of the LTM9004 and LTM9005 are now available, with production quantities expected next quarter at $75.00 each. Demo boards and samples can be obtained through the official website or by contacting your local Linear Technology office. For more details, visit their site or explore the resources provided.

Photo Caption: 14-bit, 125Msps direct conversion and IF sampling micromodule receiver