Author Topic: HMC624ALP4E based variable attenuator for the home lab?  (Read 308 times)

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Offline TheUnnamedNewbie

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HMC624ALP4E based variable attenuator for the home lab?
« on: January 10, 2018, 06:44:17 PM »
So, in my wandering over the analog devices pages, I came across the HMC624A. This is a DC-6 GHz (you can get under the 100 MHz lower limit using external capacitors) digital variable attenuator. It has parallel control or SPI input, from as far as I can tell.

It goes for about 10 Euros, which seems like a good deal to make a simple home-built variable attenuator in a compact form factor. I think that the parallel input means that you can just use a dip controller to set it, if you desire, which means that the attenuator board would just have power in, and two RF connectors of your choice. Anyone have any experience with these?

I'm looking at making a attenuator box using it. Any "traps"  I might be missing?

Link: http://www.analog.com/en/products/rf-microwave/attenuators/digital-step-attenuators/hmc624a.html?doc=HMC624A.pdf
DC is everything of which a quarter-wavelength stub does not fit on my silicon chip.
 

Offline yl3akb

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Re: HMC624ALP4E based variable attenuator for the home lab?
« Reply #1 on: January 10, 2018, 10:33:36 PM »
Hi!

I have used it in one of my projects in with frequency range from 1 MHz to 6 GHz with 100nF DC block capacitors with no issues at all. But due to its high price, now I am looking at this one, which is only around 5 EUR, has less external components and 7 bit resolution: http://www.qorvo.com/products/p/RFSA3714
 

Offline TheUnnamedNewbie

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Re: HMC624ALP4E based variable attenuator for the home lab?
« Reply #2 on: January 10, 2018, 10:50:04 PM »
Waw, thanks for the suggestion! Will definitely look at that one too. Unfortunate that it only goes down to 50 MHz, I was hoping to get something I could also use at lower frequencies since for now I don't have much gear that goes up to high frequencies. Perhaps better to build some simple resistive attenuators for now then instead. Will look at some of qorvo's other products too though, see what they have.


DC is everything of which a quarter-wavelength stub does not fit on my silicon chip.
 

Online henrikf

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Re: HMC624ALP4E based variable attenuator for the home lab?
« Reply #3 on: January 11, 2018, 02:12:36 AM »
You might want to also check out PE43711. It goes down to very low frequencies. I used this on my VNA and it worked well.
 

Offline Yansi

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Re: HMC624ALP4E based variable attenuator for the home lab?
« Reply #4 on: January 12, 2018, 08:23:12 AM »
Hi,

you may find interesting having a look in my other DDS thread here. Currently  I am also solving a design problem of a wide band variable attenuator, in fact complete ALC circuit. Some approaches to variable attenuators are evaluated (PIN, FET, stepped relay resistor, even those digital ones).

http://www.eevblog.com/forum/rf-microwave/half-decent-diy-rf-generator-utilizing-ad9951-an-idea/100/

But my thread does not seem to get much attention, so the progress is kinda slow and I am mostly making things up to move forward.
 

Offline TheUnnamedNewbie

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Re: HMC624ALP4E based variable attenuator for the home lab?
« Reply #5 on: January 13, 2018, 07:23:34 PM »
I have looked at the thread and am keeping an eye on it as it progresses Yansi! Unfortunatly I am still a beginner and really not that familiar with the design of systems and weighing different options. I'll read through the entire thread later today!
DC is everything of which a quarter-wavelength stub does not fit on my silicon chip.
 

Offline Yansi

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Re: HMC624ALP4E based variable attenuator for the home lab?
« Reply #6 on: January 13, 2018, 09:38:54 PM »
I am no less beginner than you. Feel free to ask, you may sometimes get an answer  ;D
 


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