Hi, I'm sorry if my question is too basic. I want to build FMCW radar with range 4-7GHz. Now I'm looking for the downconverter with the expected IF signal (LO-RF) is at 10-100 kHz. And I found HMC525ALC4.
But based on its datasheet, it mentions about external 90º Hybrid. Is it compulsory for me if I just need one IF port? What happen if I terminate one port with 50ohm dummy load and use another IF port directly without external 90º Hybrid?
Or, do you have any recommendation components either for the 90º Hybrid or the downconverter mixer?
Thanks,
Ghozali Hadi
Hi Ghozal,
Yes you could 50 ohm terminate an IF port and use the other IF port... Or better you could use any double balanced mixer from our portfolio:
www.analog.com/.../10711
Taz
Hi,
Using only one IF port without the hybrid would mean that you would have 3dB additional conversion loss. The hybrid is needed for image rejection. However you would lose the image rejection capability…
Hi, thanks for your answer. But I can't see the complete link which you've given in your comment. So, is it ok to use one port without external 90º Hybrid? Are there any consequences if I don't use it?
Using only one IF port without the hybrid would mean that you would have 3dB additional conversion loss. The hybrid is needed for image rejection. However you would lose the image rejection capability if using only one IF port.
I think for your application these mixers would fit better:
HMC1048A (only for downconversion)
HMC129A.
HMC218B,
HMC219B,
HMC557A,
HMC787A,
LTC5548,
LTC5552.
Ok, many thanks Taz,
Hi Taz,
I want to ask another question. I am interested in using LTC5548. But when I checked the eval-board it uses balun TC1-1-13M+ whose range is 4.5MHz-3GHz while my expected IF is in 10kHz-100kHz. Is it possible for me to request custom LTC5548 board with a balun in 10kHz-100kHz range?
Hi shsiao,
Can you comment on the above question regarding the LTC5548?
Custom evaluation board should be requested through your local ADI sales office. However, you can purchase standard evaluation board online at:
https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/dc2461a.html#eb-documentation
Thank you.
Thanks for your reply. Actually I'm also considering replacing the balun manually using T1-6-KK81+ or TT1-6-KK81+ but I'm not sure about the matching impedance because both of them have different configurations with TC1-1-13M+. Do you know how to match impedance using T1-6-KK81+ or TT1-6-KK81+?