Question

(1) Electronic Fundamentals 6 marks (la) 1 mark Fig. P-1A shows the copper trace on a printed circuit board (PCB, not to scale) and the length of the square is 10cm. Draw the equivalent circuit from the IN contact to the OUT contact showing all relevant resistors and label them R1, R2, etc. IN 5mm contact K 10cm OUT contact Fig. P-1A (1b) 2 marks Compute the approximate value of the resistance of the copper trace between the IN contact and the OUT contact of Fig. P-1A, with thickness of 200um and the resistivity of copper is p = 1.7x10 12-m. (10) 3 marks With reference to Fig. P-1B, compute the open-circuit voltage Voc and the Thevenin resistance Rth to the left of A-B. A 1kZ 1mA 422 IZR 2v +- Fig. P-1B

Answer 1

LC 4K ERL mA Ith Across AB terminals: Voc=&th Ima ♡ 4K4 K using Nodal analysis Voc + VOC-2 + Ima=0 Yo vent voce - Ixvā Voc+ 4(VOC-2) = -1x17x1084 Noc + 4V0C-8 = -4 5VOC = 8-4 = 4 Voc = = 0,8V - Voc=0.8V Rthi - open current sources short voltage sources,

Ž 4k1 7 Rth Rth = (IKA 1146A) = 1KX HK => [pth=0.8%A] w Rth=0.8kA RL Y =yot:0.5v given thicknell = 2o0um e = 1.7x10*1-m length (l) = 10cm. I Trace width = 5mm. Resistance (R) e. I.W = 1.7x108 1oxio 200x10" xsxió R = 0.01xion = 0.00170