Minimum transistor frequency

[Antenna94]

Hello!

What does minimum frequency mean in a transistor datasheet? Does it mean it cannot be used under that frequency? I have never heard of such a thing.

 

[KlausST]

Hi,

give the datasheet, or a link.

Klaus

 

[Antenna94]

for example here at the Farnell website or in the description on the first page.

 

[davenn]

for example here at the Farnell website or in the description on the first page.

I see no comment relating to minimum freq on page 1, 2 or 3

sure you didn't mis read ?

 

[Antenna94]

Last sentence of the description on the first page: "in the 450 MHz to 10 GHz frequency range". I personally never heard of such a concept as minimum frequency, but I had some trouble with an up-converting mixer simulation and had a mini heart attack that my IF frequency is too low for it to work. But if you guys haven't heard of anything like this, then I trouble-shoot elsewhere.

 

[BigBoss]

Hello!

What does minimum frequency mean in a transistor datasheet? Does it mean it cannot be used under that frequency? I have never heard of such a thing.

The Minimum Frequency term comes from Noise Figure behavior of the FETs ( or its' variants) due to its nature.The transistors have normally no low frequency limit so they work from DC to Ft but Low frequency Noise of the FETs does not permit them practically to use below certain frequency because of their bad Low Frequency Noise characteristics.

 

[davenn]

Last sentence of the description on the first page: "in the 450 MHz to 10 GHz frequency range". I personally never heard of such a concept as minimum frequency, but I had some trouble with an up-converting mixer simulation and had a mini heart attack that my IF frequency is too low for it to work. But if you guys haven't heard of anything like this, then I trouble-shoot elsewhere.

you are, as I assumed, mis-reading .... says nothing about minimum freq ... the 450MHz - 10GHz is just where it's performance is best

it will still operate well below 450MHz, but it's NF and GAIN will not be at it's best

 

[Antenna94]

Thank you very very much!!

 

[davenn]

Thank you very very much!!

you are welcome

just consider also, it's operation DOESNT stop at 10 GHZ .... it probably ( look at the graphs in the datasheet) operate to maybe 15 GHz
but once again, its performance will be down on its designed bandwidth


Dave

 

[ngochaigv888]

for example here at the Farnell website or in the description on the first page.

i think, it's range that transistor working very low noise.

 

[biff44]

all transistors have MUCH higher gain as you go to low frequency. Like a 2 GHz transistor with 12 dB gain, might have 35 dB gain at 2 MHz. But that does not stop you from using said transistor at 2 MHz, you just have to be careful you are not making an oscillator out of it.