Complex sentence: The BC548 is flanked by two similar transistors, the BC547 and the BC549, these are similar to the BC548 but the 547 has a greater Vcbo of 50 volts and the 549 has the same Vcbo of 30 volts but a lower noise figure.
Split into simpler sentences: The BC548 is flanked by two similar transistors, the BC547 and the BC549. These are similar to the BC548 but the 547 has a greater Vcbo of 50 volts and the 549 has the same Vcbo of 30 volts but a lower noise figure.