Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Figure 12.39 Analog-to-digital conversion.Figure 12.40 The DAC output is a staircase approximation to the original signal. Filtering removes the sharp corners. (Note: In addition to smoothing, the filter delays the signal. The delay is not shown.)Figure 12.49 Output versus input for a 3-bit flash A/D converter7Δ6Δ5Δ4Δ3Δ2Δ1Δ0ΔDNL (differential nonlinearity) and INL (integral nonlinearity)Figure 12.41 Circuit symbol for a digital-to-analog converter.Figure 12.42 DACs can be implemented using a weighted-resistance network.(Note: If di = 1, the corresponding switch is to the right-hand side. For di = 0, the i th switch is to the left-hand side.)Figure 12.43 An R -- 2R ladder network. The resistance seen looking into each section is 2R.Thus, the reference current splits in half at each node.Figure 12.44 An n-bit DAC based on the R–2R ladder network.Figure 12.45 Parallel, simultaneous, or flash A/D conversion.Figure 12.51a Successive approximation ADC.Initially, all bits are set to 0In step 1, the control logic sets MSB to 1 and if the comparator output is high, MSB is set back to 0, otherwise MSB remains 1The process is repeated for the next bit. After n steps, the process is complete, and the input to the DAC is the digital code for the analog input.Oversampling A/D convertersE(n)=Y(n)-X(n) is defined as quantization noise, Y(n) is the quantized output and X(n) is the input. E(n) is between (-∆/2, ∆/2) Where ∆ is the quantization level.E(n) is typically approximated as an independent uniformly distributed white noise and its power spectral density is k= , fs is the sampling frequency.Therefore, increase the fs relative to the signal bandwidth will give higher resolution than Nyquist sampling converters.Even further, if oversampling is combined with noise shaping, such as in a Sigma-Delta A/D converter, then the resolution could be even