a) Design the base-emitter area of NPN BJT so that its transconductance gain is gm=2 A/V at VBE=0.70 V. The technological parameters are as folows: the emitter is heavily doped, the base doping is 5*1017cm-3,the base width is W=0.5μm and the electron mobility in the base is μn=300 cm2/V.s.
b) Room temperature (300K) is assumed in part (a). What would be the transconductance gain at T=55C? Assume that the electron mobility does not change and ni ≈7.5*1010cm-3.