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7.6: Case Study- Analysis of a 15 GHz Receiver

  • Page ID
    46154
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    Most RF and microwave systems convert information at one frequency to information at another frequency that can either be more conveniently processed in the case of a receiver or more conveniently radiated in the case of a transmitter. Figure \(\PageIndex{1}\) is a \(15\text{ GHz}\) receiver module which itself consists of interconnected sub modules. Detail of the frequency conversion section is given in Figure \(\PageIndex{2}\).

    These sub modules could be called modules as well so that modules are constructed by interconnecting other modules many of which are available ”off-the-shelf” from high-level modules such as a receiver. The receiver module is part of a wireless service used in point-to-point microwave link such as in a cellular systems to provide communication between

    clipboard_e6be48d6b50c56b4b287e7ae756c3558b.png

    Figure \(\PageIndex{1}\): A \(14.4–15.35\text{ GHz}\) receiver module itself consisting of cascaded modules interconnected by microstrip transmission lines. Surrounding the microwave circuit are DC conditioning and control circuitry. Detail of the frequency conversion section mounted on the mat is shown in Figure \(\PageIndex{2}\).

    clipboard_e5945a38e6022dba516772d4edba4de73.png

    Figure \(\PageIndex{2}\): Frequency conversion section of the receiver module shown in Figure \(\PageIndex{1}\). The reference LO is applied to the frequency conversion section at \(\mathsf{c}\), the RF is applied at \(\mathsf{h}\) following the isolator. The IF is output at \(\mathsf{j}\).

    basestations. The subsystem modules such as the amplifiers, frequency multipliers, mixers, isolator, and waveguide adapter are available as off-the-shelf components from companies that specialize in developing such modules and selling them to a large user base. The block diagram of the receiver module is shown in Figure \(\PageIndex{3}\).

    The RF module engineer must interconnect these modules and mange interference and dynamic range. The RF module designer either designs the various filters or specifies them for design and fabrication by specialty microwave filter companies. The conductive die attach mat \(\mathsf{H}\) is material silk-screened on to the brass back-plate and enables the alumina interconnects, and the amplifier and mixer die, to be epoxy-attached. It is not wise to directly attach die and ceramic substrates directly to the brass housing as the difference in thermal coefficients of expansion and the rigidity of the two systems means that the attachment could fail or the ceramic and die crack. The mat is said to be ‘compliant’ providing stress relief when the solid

    clipboard_e0d65db5cfa4ec230b69c7fc369d7b000.png

    Figure \(\PageIndex{3}\): Block diagram of the receiver module shown in Figure \(\PageIndex{1}\).

    objects expand at different rates. The ceramic substrates, usually alumina, have repeatable and stable dimensions for realization of filters which have a response that strongly depends on dimensions.


    7.6: Case Study- Analysis of a 15 GHz Receiver is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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