Question

Figure 2 shows an 8-bit voltage-mode DAC implemented with an LM385 2.5V Zener diode and a 741 op amp. R1 = 10 kQ. R2 = 30 kΩ and R = 10 k(2. Switches SW1. SW2. SW8 are controlled by bl, b2,... b8, respectively a. Find VFSR, VFSv, resolution of the DAC b. Find the corresponding output voltages for the digital inputs of 1000000 and 11000000 (Show your work) R2 2R 2 6.2 Sw zm3釘 又5

Answer 1

(a) Resolution of DAC = vr/2^n = 0.585 volt V-Fs = v_r = 15 volt (b) V_0 = Resolution times Digital equitant times gain = R sigma_i = 0^N (1 + R_2/R_1) for digital input 100000 v_0 = 15 volt for digit input 1000000 V_0 = 4.5 volt