A lateral pnp transistor has an effective base width of 10 m (1 m = 10

A lateral pnp transistor has an effective base width of 10 µm (1 µm = 10⁻⁴ cm).

(a) If the emitter-base depletion capacitance is 2 pF in the forward-bias region and is constant, calculate the device f_T at I_C = −0.5 mA. (Neglect C_μ.) Also, calculate the minority-carrier harge stored in the base of the transistor at this current level. Data: D_P = 13 cm²/s in silicon.

(b) If the collector-base depletion layer width changes 0.11 µm per volt of V_CE, calculate r_o for this transistor at I_C = −0.5 mA.