For a npn BJT transistor fβ is 1.64 x 108 Hz. Cμ = 10-14 F; Cp = 4 x 10-13 F and DC current gain is 90. Find fT and gm (fβ = cut off frequency, Cμ = capacitance, Cp = parasitic capacitance, gm = transconductance, fT = gain BW product)

• A. fT = 1.47 x 1010 Hz ; gm = 38 milli mho
• B. fT = 1.64 x 108 Hz ; gm = 30 milli mho
• C. fT = 1.47 x 109 Hz ; gm = 38 mho
• D. fT = 1.33 x 1012 Hz; gm = 0.37 m-mho