about 60GHz downconvertor

[RF_beginner]

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!!!

 

[mr_ghz]

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

 

[RF_beginner]

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!

 

[mr_ghz]

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

 

[syncmaster]

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.

 

[mr_ghz]

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

 

[yykk]

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.


Hi, mr_ghz
what is the order of your ham-mixer ??? why use the DMK2790 not 2308 ????

Bye

 

[mr_ghz]

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