1. The problem statement, all variables and given/known data Design the following circuit, common source with source resistance, in fig. (1). It uses the MOSFET (irfp244) where Vt= 4.15V, KN = Kn(W/L)= 2.87 A/V2. Assume vin = +/- 100 mV, DC offset = 5 V, and the frequency = 1 K Hz. a) Design R1 and R2 so that the small signal output gain, Av, is ~ 5. Assume 1/gm << R2. b) What is the value of ID? c) Plot Vout & Vin when vin = +/- 400 mV, +/- 700 mV, and +/- 1V separately. d) Explain why the small signal gain collapses as the input is increased. 2. Relevant equations Id = (1/2) KN (VGS - Vt)2 Id = Vsource / R2 , Id = (10-Vout) / R1 , Av = Vo/Vin = R1 /((1/gm)+R2) 3. The attempt at a solution Now what I did I assumed that from Av = R1/R2 =5 that R1=250ohm and R2=50ohm I found from Id = (1/2) KN (VGS - Vt)2 & Id = Vsource / R2 that Vs = 0.96599V or Vs = 0.74794V the first Vs is not accepted because the N-MOSFET will be off (Vgs > Vt) and the second will be on ( VG-Vg swing - Vs > Vt) . and the value for Id will be 14.9588 mA . but the problem is changing the Vin ! because the mosfet will be cut off from (Vg - Vg swing - Vs < Vt) but the multisim still give me value for Vout and Vin for different Av , Can any one tell me what i did wrong ?