oscillator design @24GHz - which transistor

You should select a transistor that is somewhat faster, choose one that makes 45 GHz or more. There is BFP520 with an Ft of 45GHz and the BFP620 with an Ft of 65GHz, both NPN bipolars in SOT cases though.

Tuneable ?

Rene

Checked the NEC phemts?

What sort of resonator did you have in mind?

John

Hi John,hi Rene

thanks for the quick answer - for the Infineon npn-transistors I didn't find any data above 6 GHz. The resonator will be a microstrip parallel feedback resonator - no DRO because of difficulties in positioning in mass production and cost issues. The pHEMT transitors from NEC I have already checked and I think they are quite good, I also found some from Mitsubishi and NEC, but I am not sure whether there are any others ? So if somebody has already designed a transistor ocillator with discrete transitors - please let me know what kind of transistor did you use.

Thanks a lot.

Peter

Hi John,hi Rene

thanks for the quick answer - for the Infineon npn-transistors I didn't find any data above 6 GHz. The resonator will be a microstrip parallel feedback resonator - no DRO because of difficulties in positioning in mass production and cost issues. The pHEMT transitors from NEC I have already checked and I think they are quite good, I also found some from Mitsubishi and NEC, but I am not sure whether there are any others ? So if somebody has already designed a transistor ocillator with discrete transitors - please let me know what kind of transistor did you use.

Thanks a lot.

Peter

Not very close but I made a 1-2ghz vco with a PHEMT JFET I got from ebay, unfortunatly havnt got the part no. to hand atm, but the device marking is 'D' so its probably got a very long number. It was just a delay line type feedback curtuit, It was quite a high freq device and probably still has enough gain to oscillate at that frequency, although ive no way of testing at anywhere near that, sounds interesting.

Colin =^.^=

Hi Colin,

this sounds interesting - I would be very glad if you can find out the name of the transitor. Thanks for your help.

Peter

I've never tried to go that fast, but it seems to me that a bipolar with a 45 Ghz Ft only has a beta of 2 at your frequency, which doesn't bode well for making a good oscillator. A phemt would seem a better choice to me.

John

managed to find it eventually, my disc got corupted NE32584C

its got specs upto20ghz

even got a model upto 18ghz

posibly got >9db of gain at 24ghz

Colin =^.^=