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Microwave Integrated Circuits

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Some history of MIC

New for February 2019: microwave integrated circuits date back to the 1970s, when microstrip was not exactly new, but it was first being stuffed with discrete components.   A rough definition is: microwave circuits employing discrete components (caps, resistors, diodes, transistors...) based on chip-and-wire construction, with ceramic microstrip interconnects.  Often abbreviated as MIC, these are the precurser to MMIC, which adds "monolithic" to the name.  We shouldn't have to tell you what monolithic means, but it is literally "one stone", meaning all the circuits were built on a single chip.  The megalomaniacal leader of Germany in the 1930s was also reportedly "monolithic", in a different sense of the word.

MIC circuits were revolutionary, in that they replaced waveguide-based hardware, greatly increasing functional density.  More info can be found on the Wikipedia page on microwave integrated circuits.

The video below is an historical artifact from 1974, but it is also a great intro to what MIC circuits are today. Here you will see a 4-12 GHz multi-channel receiver that uses 25 mil alumina substrates (which seem pretty tall for 12 GHz). There are tons of suppliers that still make amplifiers, mixers, receivers... using discrete components. In many cases an MIC circuit can have higher performance compared to its MMIC counterpart, as area is not so precious so lower-loss networks can be obtained using thicker substrates. 

 

Microwave Integrated Circuits, United States Air Force Systems Command, 1974

We'll add some example MIC circuits to this page soon.  Meanwhile, check out our page on chip-and-wire construction, which has some nice photos of MIC circuits, next to MMIC circuits, which is sometimes called a "hybrid module".

 

 

 

Author : Unknown Editor

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