Optimal Design of Opamps for Oversampled Converters

The power consumption for various opamps used in EA modulators are considered. We first classify the different opamp topologies used in such modulators. We then develop a generalized in- tegrator model that allows us to compare the power consumption for all these topologies. We also derive an expression for the minimum theoretical bound on the power dissipation. We illustrate our results with two design examples: a class A and a class AB opamp. It is shown that class A opamps are the best choice for EA modulators.

[1]  Willy Sansen,et al.  The current efficiency of MOS transconductance amplifiers , 1984 .

[2]  R. Castello,et al.  A high-performance micropower switched-capacitor filter , 1985, IEEE Journal of Solid-State Circuits.

[3]  H.J. De Man,et al.  Adaptive biasing CMOS amplifiers , 1982, IEEE Journal of Solid-State Circuits.

[4]  K. Nagaraj.  CMOS amplifiers incorporating a novel slew rate enhancement technique , 1990, IEEE Proceedings of the Custom Integrated Circuits Conference.

[5]  Willy Sansen,et al.  Class AB CMOS amplifiers with high efficiency , 1990 .

[6]  Ramesh Harjani,et al.  A low voltage class AB CMOS amplifier , 1996, 1996 IEEE International Symposium on Circuits and Systems. Circuits and Systems Connecting the World. ISCAS 96.

[7]  Rinaldo Castello,et al.  Performance limitations in switched-capacitor filters , 1985 .

[8]  M.G.R. Degrauwe,et al.  A multipurpose micropower SC filter , 1984, IEEE Journal of Solid-State Circuits.

[9]  Bedrich J. Hosticka,et al.  Dynamic CMOS amplifiers , 1980 .

[10]  B. Hosticka,et al.  A very-high-slew-rate CMOS operational amplifier , 1989 .

[11]  M. Degrauwe,et al.  Class AB CMOS amplifier micropower SC filters , 1981 .

[12]  G. A. Miller,et al.  A high-slew integrator for switched-capacitor circuits , 1994 .

[13]  Ramesh Harjani,et al.  Dynamic amplifiers: settling, slewing & power issues , 1995, Proceedings of ISCAS'95 - International Symposium on Circuits and Systems.