Hi,
I am looking for a readily available PNP transistor in a through-hole package with as small a collector-base ("Miller") capacitance as possible. It is to be used for moderately fast saturated switching (t-on and t-off of a few 10ns) at low power (Ic about 1mA). Maximum collector voltage (9V battery) is no problem.
I have tried the BF324 and BF450 (both Philips) with reasonable results. The limiting factor here indeed appears to be the collector-base capacitance: measured zero-bias values are ~3pF and ~2pF, respectively. Fast PNP switching transistors like the 700MHz 2N5771 are not automatically better suited.
So, what is the ultimate PNP transistor for this type of application? Is something like the 5GHz BFT52 (Ccb ~ 1pF according to the Philips Spice model) still available in a through-hole package? Operation with E and C interchanged may also be considered if the reverse beta exceeds five.
TIA,
Martin.