High Frequency Problems

does using leaded components for example a TO92 packaged transistor at 900MHz makes problems? is there any tips in the design to avoid the problems that may occure?

regards

in RF design always use surface mount components , with very short leads
the leads will add capacitance and inductance , which will make the circuit doesnot work as expected

but u can still use leaded components up to 100 or 150 MHz
for 900 MHz ragne use surface mount

wish this help

khouly

I would say that leaded components can be used to at least 500MHz (just look at radioamateur Rx and Tx designs), with proper design and knowledge of the package parasitics. I agree that the TO-92 package is a little too big for 900 MHz. What you must be careful about with leaded components at high frequencies is unexpected resonances due to the lead inductances, loss of gain, instability, capacitors acting like inductors, ... , whose probabilities can be reduced when using lead lengths as short as possible.

i have used some leaded components in RF design
but i cut out the leads , and use the components as surface mount this method is custom to make RF circuits in home

but the package parasitics cannot be canceled , so u must have a good model for these pacakegs , spically the inductances

about the PCB , try to make the lines as short as possible , and use TL , microsrtips or coplaners , and take care for the ground plans


wish this help

khouly