The fTmin, minimum Transition Frequency, for discrete BJT 2N3904/2N3906 is 300MHz at IC = 10mA, VCE = 20V with Beta0min =100, Beta0max = 300, therefore f(-3Db)min = 300 MHz/100 = 3 MHZ. Any variation of IC or VCE will decrease this, I'm trying to determine relationship with some success. In the 70's Integrated Circuits used a collector current of ~1mA, what do they use today or are they still limited by leakage current. Note Beta0min, Beta0max given for VCE = 1V, the actual Beta0s will be larger at VCE = 20 V due to the Early Voltage, about 5 to 10 %

Question

The fTmin, minimum Transition Frequency, for discrete BJT 2N3904/2N3906 is 300MHz at IC = 10mA, VCE = 20V with Beta0min =100, Beta0max = 300, therefore f(-3Db)min = 300 MHz/100 = 3 MHZ.  Any variation of IC or VCE will decrease this, I'm trying to determine relationship with some success.  In the 70's Integrated Circuits used a collector current of ~1mA, what do they use today or are they still limited by leakage current.  Note Beta0min, Beta0max given for VCE = 1V, the actual Beta0s will be larger at VCE = 20 V due to the Early Voltage, about 5 to 10 %