As mentioned in the function of D1 in is to improve the line-regulation capabilities of D2. Moreover, R1 and R2 must be small enough to guarantee a predetermined minimum current through each diode...

As mentioned in the function of D1 in is to improve the line-regulation capabilities of D2. Moreover, R1 and R2 must be small enough to guarantee a predetermined minimum current through each diode under all possible line and load conditions. (a) Assuming VI 5 (30 6 5) V, VZ01 5 14.7 V, rz1 5 15 V, VZ02 5 9.8 V, rz2 5 10 V, and 0 # IL # 10 mA, specify 5% standard values for R1 and R2 to ensure IZ(min) 5 5 mA for each diode. (b) Estimate the line and load regulation (in mV/V and mV/mA) of your circuit.