On the Design of Very Small Transconductance OTAs with Reduced Input Offset

This paper demonstrated from the theory and measurements, that series-parallel (SP) mirrors allow building current copiers with copy factors of thousands, without degrading mismatch or noise performance. SP current-division is then employed to design OTAs ranging from a few pS to a few nS, with up to 1V linear range, consuming in the order of 100nW, and with a reduced area. An integrated 3.3s time-constant integrator was also presented. One-by-one several design non-idealities are revised: linearity, offset, noise, leakages; as well as layout techniques. A final analysis concludes that SP-association of transistors allows to build very efficient transconductors, for demanding applications in the field of implantable electronics among others

[1]  Edgar Sanchez-Sinencio,et al.  A CMOS transconductance amplifier architecture with wide tuning range for very low frequency applications , 2002 .

[2]  Carlos Galup-Montoro,et al.  Pico-A/V range CMOS transconductors using series-parallel current division , 2003 .

[3]  Carlos Galup-Montoro,et al.  A fully integrated physical activity sensing circuit for implantable pacemakers , 2004, Proceedings. SBCCI 2004. 17th Symposium on Integrated Circuits and Systems Design (IEEE Cat. No.04TH8784).

[4]  Francois Krummenacher,et al.  A 4-MHz CMOS Continuous-Time Filter with On-Chip Automatic Tuning , 1987, ESSCIRC '87: 13th European Solid-State Circuits Conference.

[5]  Carlos Galup-Montoro,et al.  Series-parallel association of FET's for high gain and high frequency applications , 1994, IEEE J. Solid State Circuits.

[6]  Marcel J. M. Pelgrom,et al.  Matching properties of MOS transistors , 1989 .

[7]  Jorge Salcedo-Suñer,et al.  IC Voltage to Current Transducers with Very Small Transconductance , 1997 .

[8]  A. Demosthenous,et al.  A 230-nW 10-s time constant CMOS integrator for an adaptive nerve signal amplifier , 2004, IEEE Journal of Solid-State Circuits.

[9]  Edgar Sanchez-Sinencio,et al.  Transconductance amplifier structures with very small transconductances: a comparative design approach , 2002 .

[10]  Bernabé Linares-Barranco,et al.  On the design and characterization of femtoampere current-mode circuits , 2003, IEEE J. Solid State Circuits.

[11]  Carlos Galup-Montoro,et al.  An MOS transistor model for analog circuit design , 1998, IEEE J. Solid State Circuits.

[12]  Peter R. Kinget,et al.  Full analog CMOS integration of very large time constants for synaptic transfer in neural networks , 1992 .

[13]  Carlos Galup-Montoro,et al.  Consistent noise models for analysis and design of CMOS circuits , 2004, IEEE Transactions on Circuits and Systems I: Regular Papers.

[14]  Rahul Sarpeshkar,et al.  A practical micropower programmable bandpass filter for use in bionic ears , 2003, IEEE J. Solid State Circuits.

[15]  Rahul Sarpeshkar,et al.  A Low-Power Wide-Linear-Range Transconductance Amplifier , 1997 .