Section 5.10 Applications

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Section 5.10 Applications

5.82 A four-bit DAC covers a voltage range of 0 to 10 V.

Calculate the resolution of the DAC in volts per discrete binary step.

5.83 Design a six-bit digital-to-analog converter.

• (a) If |Vo| = 1.1875 V is desired, what should [V1V2V3V4V5V6] be?
• (b) Calculate |Vo| if [V1V2V3V4V5V6] = [011011].
• (c) What is the maximum value |Vo| can assume?
• 5.84 A four-bit R-2R ladder DAC is presented in Fig. 5.103. *
  • (a) Show that the output voltage is given by

$$-V_o = R_f \left( \frac{V_1}{2R} + \frac{V_2}{4R} + \frac{V_3}{8R} + \frac{V_4}{16R} \right)$$

(b) If Rf = 12 kΩ and R = 10 kΩ, find |Vo| for [V1V2V3V4] = [1011] and [V1V2V3V4] = [0101].

• For Prob. 5.84.
  • 5.85 In the op amp circuit of Fig. 5.104, find the value of R so that the power absorbed by the 10-kΩ resistor is 10 mW. Determine the power gain.

Figure 5.104 For Prob. 5.85.

• 5.86 Design a voltage controlled ideal current source (within the operating limits of the op amp) where the output current is equal to 200 vs(t) μA.
• 5.87 Figure 5.105 displays a two-op-amp instrumentation amplifier. Derive an expression for vo in terms of v1 and v2. How can this amplifier be used as a subtractor?

Figure 5.105 For Prob. 5.87.

5.88 Figure 5.106 shows an instrumentation amplifier driven by a bridge. Obtain the gain vo∕vi of the amplifier. *