Question

Problem 1 (20 %) We want to analyse an electrical circuit described as a 2-port (Figure ). The circuit has source terminal with a constant ideal voltage source Vs and a loading terminal with a loading resistor Ri. Circuit with passive components Figure 1. General electric circuit We want to represent the circuit as seen from the loading terminal as a Thevinin and a Norton equivalent. Sketch these crt equivalents and describe the steps how to determine their component values. a) b) f we want Vi to best represent the value of Vs, what restrictions must apply to R when the equivalent is Thevinin or Norton? We now assume that the electric circuit in Figure is a Wheatstone bridge with 4 variable piezo-resistors R, R2, R3 and R, İmplanted on a rectangular silicon beam clamped to a wall as outlined in Figure 2. The beam is assumed to be perfectly elastic and is bent downwards by an external contact forceF Figure 2. Rectangular silicon beam with dimensions I(length) w (width) and i (thickness). c) Show how the piezo-resistors Ri, R, R and R can be connected in a 4-element d) Can we use only one piezo-resistor Ri implanted on the beam and the others as fixed e) If we assume I's to be the voltage from an oscillator. What is the purpose with such a Wheatstone bridge and find an expression for the voltage at the loading terminal. resistors placed outside the beam? Discuss the limitations with such an arrangement modification?

Answer 1

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