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8 marksOperational Amplifiers

CAPE Physics Unit 2 · May/June 2021 · Paper 2 · Question 2(c)(i)

Figure 5 shows an operational amplifier summing inverter which may be used as a digital to analogue (D/A) converter.

Consider the case where a digital 1 is represented by 1 V and a digital 0 by 0 V. Complete Table 2 for the input-output characteristics of a 3-bit D/A converter.

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Other parts of this question

  1. 2(a)State THREE major properties of an ideal operational amplifier and explain how EACH property manifests itself when the operational amplifier is placed in a…[6 marks]
  2. 2(b)(i)Draw a diagram of a non-inverting operational amplifier circuit, labelling all important currents and voltages.[2 marks]
  3. 2(b)(ii)Use your diagram in (b) (i) to derive the relationship between input voltage and output voltage for the non-inverting operational amplifier circuit.[2 marks]
  4. 2(b)(iii)A non-inverting operational amplifier circuit has a gain of 11. Suggest practical values for the resistors in your circuit in (b) (i) which will achieve this…[2 marks]
  5. 2(b)(iv)On the diagram in Figure 4, sketch the output waveform, labelling the maximum and minimum points.[3 marks]
  6. 2(b)(v)State the values of the output at t = 2 ms and t = 14 ms.[2 marks]
  7. 2(c)(ii)Calculate values for the resistors in Figure 5 such that the input-output characteristics of Table 2 would be realized.[4 marks]
  8. 2(c)(iii)State the MAJOR disadvantage of the circuit in Figure 5 when used as a D/A converter.[1 mark]

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