Draw the schematic of a folded-cascode op amp similar to the op amp in Fig. 6.28 except with two layers of both n- and p-type cascodes. Choose a current mirror that maximizes the output swing. Assume that all transistors have equal overdrive magnitudes except where changes are needed to maximize the output swing. Use the models in Table 2.4 and ignore the body effect. Specify the W/L ratios in multiples of (W/L)₁.

Figure 6.28

Table 2.4

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VDD M4 VBIAS1 Мз M5 МАл Мзл M2 M1 CL УBIAS2 УBIAS2 M2A M1A УBIAS3 УBIAS3 M12 M11 -Vss Value Value n-Channel p-Channel Parameter Symbol Transistor Transistor Units Substrate doping Gate oxide thickness 5 x 105 4 x 1016 Atoms/cm NA, ND lox 80 80 Metal-silicon work function Фия -0.6 -0.1 450 cm?/V-s Channel mobility Minimum drawn channel length Source, drain junction depth Source, drain side diffusion 150 Larwn 0.4 0.4 um X) L4 0.15 0.18 um 0.09 0.09 um Overlap capacitance per unit gate 0.35 0.35 fF/um width Threshold adjust implant (box dist) impurity type effective depth effective surface х, 0.16 4 x 1016 0.16 Nsi 3 x 1016 Atoms/cm concentration Nominal threshold voltage Polysilicon gate doping concentration V, Napoly 0.6 100 -0.8 100 Atoms/cm Poly gate sheet resistance Source, drain-bulk junction R, Cp 0.2 0.4 fF/um? capacitances (zero bias) Source, drain-bulk junction capacitance grading coefficient 0.5 0.4 Source, drain periphery capacitance (zero bias) Source, drain periphery Суио 1.2 2.4 F/μη 0.4 0.3 capacitance grading coefficient Source, drain junction built-in potential 0.7 0.7 Os Surface-state density 10! 10" Atoms/cm? Channel-length modulation parameter ах, dV ps 0.02 0.04 um/V