about 60GHz downconvertor

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RF_beginner

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i'd like to design a x4 subharmonic mixer which works during the frequency from 59.5GHz to 60.5GHz(IF 4GHz) .can anybody tell me some tips that i must emphasizes in my design process .thanks
in addition,i'd like to find some relatively materials ,hope that every friends here can afford some information.thanks!!!
 

Hi RF_beginner

Do you need this mixer for up- or for downconverting (receiving or transmitting) or even for both? Do you plan to use microstrip technology or waveguide?

Bye
 

hi,mr_ghz,the mixer i want to design is for downconverting(receiving) and i'd like to use microstrip technology,would you please give me some advice?thanks lot!
 

Hi RF_beginner

I do not know how familiar you are with such high frequencies. Building a microstrip device in this frequency region is a very difficult task. But perhaps one of the following (other) ideas can also help you:

1. You can use a harmonic mixer that can be bought as add-on for spectrum analyzers. Some of them can be obtained for a affordable price (look for refurbished ones). Look at h**p://www.oml-mmw.com/spectrum/hman.htm to get an idea. These mixers are waveguide ones and are normally fed with a LO in the range of 2..6 GHz. Additionally you need an external waveguide filter.

2. You can build your mixer as an unbalanced one in a waveguide. This is much easier than a microstrip circuit (etching tolerances!). The mixing diode you use for it, can be "lend out" from a Gunn-source (M/A-Com) working at 24GHz.

3. If you really want to design a microstrip one, this can help you perhaps:
A few months ago I designed a harmonic mixer at 43GHz. I used a 90° hybrid and two Flip-Chip diodes (DMK2790 from Alpha Industries). This gave me a conversion loss of about 13dB. The PCB was a RT-Duroid with er of 2.2.

Bye
 

I want to know what kind of pcb material can operate at such high frequency, can RT-Duroid 5880 fit this need? and what about the thickness? I am new to design high frequency circuit up tp 60 GHz, and I need your help.
 

Hi syncmaster

The problem of PCB material at such high frequencies is, that they are not specified for. You have to measure out er and tan d.
At 60GHz I would use Rogers RO3000 series, but RT Duroid should also work. About the thickness: the thinner the better! I work with 10 mils. Because of the stability you have to use multilayer.

Bye
 

 

Hi yykk

This mixer worked on the 3rd harmonic. The LO signal has 14.25GHz at +20dBm. The ZF Signal goes from 100MHz to 350MHz.
I used the DMK2790 diode because this mixer topology uses two single diodes and not a double (antiparallel) one.

Bye
 

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