Consider a first-order hold preceded by a sampler. The input to the sampler is x(t) and the output of the first-order hold is y(t) In the first-order hold the output y(1) for kT st < (k + 1)T is the straight line that is the extrapolation of the two preceding sampled values, x((k - 1)7) and x(kT), as shown in Figure 3-50 The equation for the output y(t) is t- kT y(1) = (x(kT)- x(k - 1)7)] + x(k7), kT sI < (k + 1)7 (3-78) Obtain the transfer function of the first-order hold, assuming a simple function such as an impulse function at 0 as the input x(1). vir Tieure 3-50 Joput and output curves for a first-order hold 27 37 47 ST 67