Let's design an ideal equalizer that provides four dB positive slope over the same frequency band, using ADS. You can cascade two of these puppies and get more than 20 dB gain at 40 GHz, but you will have four dB of gain tilt, which won't go away using a conventional attenuator. A good choice is the TGA4830, below we have pilfered its gain response from TriQuint's on-line data sheet. Don't ask why, just do it! You decide to use a TriQuint MMIC, because you feel sorry for everyone that has stock options in TQNT, and you are hoping that by purchasing a few hundred amplifiers, you will put them one more wafer away from bankruptcy. You have to build a wideband module, 1 to 40 GHz, with 20 dB of flat gain. We need to take a photo of the configuration, and generate some plots, check back later for more details. This is certainly the poor-man's equalizer! Just move the ground via a few hundred mils from the chip with some transmission line, and you're styling. All you've got to do is mount a 3 dB chip attenuator, with some added inductance to ground. The gain plot below shows that it tilts about one dB from 3 to 7 GHz.įixing this is an easy assignment, we're going to show you how to do it with a conventional surface-mount attenuator chip. Here, you want to straighten out the gain of M/A-COM's MAAM37000-A1G surface mount LNA. Sorry, we're not gonna provide any links to equalizer vendors here, unless they show us the money! Equalizer example 1: C-band equalizer There are not many microwave vendors that advertise equalizers as part of their wares, many of the techniques for this remain trade secrets of companies doing wideband work. We have a separate page on parabolic equalizers. The antidote to negative gain slope is adding a linear gain equalizer that has a positive gain slope to your lineup.Ī second type of gain equalizer provides a "parabolic" response, which is used to counteract the gain of wideband traveling wave tubes. Most stuff has a negative gain slope (it has less gain, or more loss, the higher in frequency you go) This includes not only amplifiers, but passive stuff like coax cables and microstrip transmission lines as well. Perhaps the most common is to fix the problem of wide-band microwave systems. There are many reasons you might want to use an equalizer. What's a gain equalizer (or "equalizer" for short)? It's a special attenuator that has a frequency response that is intentionally not flat. Click here to visit our main page on attenuators.Ĭlick here to go to our page on parabolic equalizers.Ĭlick here to see a second parabolic equalizer exampleĬlick here to find gain equalizers on everything RF.
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