| Products > Test Equipment |
| Picotest Injector Teardowns |
| << < (11/15) > >> |
| Sighound36:
Pretty respectable trace there for a 3Ghz bandwidth :) Ok not being an RF guy, so shoot me :-DD, would it not be better to have less capacitors with a larger value? Or is this a fundamental issue with this portion of the design? |
| Jay_Diddy_B:
--- Quote from: Sighound36 on May 27, 2020, 03:47:17 pm ---Pretty respectable trace there for a 3Ghz bandwidth :) Ok not being an RF guy, so shoot me :-DD, would it not be better to have less capacitors with a larger value? Or is this a fundamental issue with this portion fot he design? --- End quote --- The capacitors I used are each 10uF 50V X5R 1210. The idea of such a high value is to get a low frequency -3dB point. 12 x 10uF / 2 = 60uF R= 25 \$\Omega\$ F = 1/(2 x Pi x R x C) = 26.5 Hz Regards, Jay_Diddy_B |
| Jay_Diddy_B:
Hi, Here are some TDR measurements made with a Tektronix 11801 and SD24 sampling head. The Bias injector was place between two lengths of semi-rigid 50 \$\Omega\$ cables: From left to right The 50 Ohm cable the first 'wiggle' is the transition from the cable to the board, the SMA edge launch. Then a short piece of 50 Ohm track. two sections of 45 Ohms, about 25mm long, where the capacitors are 50 Ohm track SMA connector 50 Ohm cable I have marked the measured impedances on this drawing of the board assembly: to raise the impedance where the capacitor are, I need to widen the gap between the traces and the ground plane. Regards, Jay_Diddy_B |
| Sighound36:
In a very crude way that is the situation I was attempting to elude to :-[ Great stuff Jay, really do not know where you find the time but top man 8) |
| 2N3055:
Nice demonstration of usefulness of TDR.. Great work (as always!!) Jay.. Regards, Sinisa |
| Navigation |
| Message Index |
| Next page |
| Previous page |