Question

For a four resistors n-channel JFET, find the operating points (V_GS, I_D, and V_DS).

Assume I_DSS = 5mA, V_P = - 4.5V and I_G ≈ 0      

Given: V_DD = 12 V, R₁ = 2MΩ, R₂ = 1.5MΩ, R_D = 6 kΩ, R_SS = 4 kΩ

Answer 1

Soln 12 V Ioss = 5MA , Vp = -4,50 JIO ²6kn Io=0 2m THEO VG Vs 31.5MM 4kn YID By Voltage division VG = 1.5 mm 1.5Mn +2mn X/2 V 1.5 -X12 V = 5.14 U 3.5 Vos 5.14V 2 ID Tors 1- Von Vp Vs= 4K2X ID 2 ID = 5mA 1- (5.14-4 K1X TO) - 4.5 2 I- 1 + 5.14-4 KvX ID 4.5 200 I 9.64 -UK ID 2 4.5

200 ID x 4.5 a 9.64 - UKID Ich Si=a 14.142x 4.5 = 9.64-4000 x By solving x = SID 41-77x10-3 In = 1.74MA Now V5 = ID . Rs = 1.74X4 INS = 6.96 V Nos . VG-Vs = 5.41-6.96 V = -1.82 V VGS =-ve So JFET is in cut off mode. JFET+Off so ID=0 NOW Vs VGS = = 5:14V VG-Us Vo - V5 NOS = 12-0 =129 And