conversion loss clarification for minicircuits zem4300 mixer - RF Cafe Forums

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balajisu

Post subject: conversion loss clarification for minicircuits zem4300 mixer Posted: Thu Sep 08, 2005 1:32 pm

Captain

Joined: Wed Jul 06, 2005 5:54 pm

Posts: 24

Location: Germantown,MD

hi guys

when i try to measure the conversion loss of minicircuits zem4300 mixer i see a notch near DC rather than seeing a flat response. A colleague of mine was confident that zem4300 has a flat response from DC.

From my measurement observation i believe there is a rolloff of conversion loss near dc.

Can anyone clarify in this part.

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rod

Post subject: Posted: Thu Sep 08, 2005 4:51 pm

are you doing this measurment with your ac coupled analyzer?

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balajisu

Post subject: discussion continuedPosted: Thu Sep 08, 2005 5:40 pm

Captain

Joined: Wed Jul 06, 2005 5:54 pm

Posts: 24

Location: Germantown,MD

i measured the conversion loss using a VNA. ( conversion loss mode/mixer measurement mode)

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Rod

Post subject: Posted: Fri Sep 09, 2005 6:18 pm

I guess my point was that when LO=RF the output = dc.

Since your analyzer rolls off below 30Khz or so, you should expect to see a notch.

Measure the mixer's IF port to ground with an ohmmeter. If you see a resistance, than you can assume the IF will operate down to dc.

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balajisu

Post subject: thanks rodPosted: Fri Sep 09, 2005 7:56 pm

Captain

Joined: Wed Jul 06, 2005 5:54 pm

Posts: 24

Location: Germantown,MD

hi rod sorry for misunderstanding ur point.

actual setting was rf swept from 750-850mhz and lo was maintained at 800mhz..

so with this setting i observed a notch behaviour near dc i .e rf = lo

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balajisu

Post subject: clarify?Posted: Fri Sep 09, 2005 7:59 pm

Captain

Joined: Wed Jul 06, 2005 5:54 pm

Posts: 24

Location: Germantown,MD

hey rod

could u clarify on: analyser rolls off 30khz or so..

thanks

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Rod

Post subject: Posted: Fri Sep 09, 2005 8:10 pm

right, when the LO and RF = 800MHz, the output = 0Hz or DC.

Assuming your are using an 8753 type analyzer, the input cannot measure DC or anything below 30Khz...depends on your VNA model.

The mixer you are refering to makes for a good phase detector, which of course has a DC output.

It's time to admit to your co-worker that he was right....have a nice weekend!

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balajisu

Post subject: thanksPosted: Sun Sep 11, 2005 6:37 pm

Captain

Joined: Wed Jul 06, 2005 5:54 pm

Posts: 24

Location: Germantown,MD

thanks a lot Rod.

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Rod

Post subject: Posted: Mon Sep 12, 2005 6:29 pm

You're welcome.

Hey, and don't worry about it. I've been wrong like 18 times today, and it's not even lunch yet.

Posted  11/12/2012