Adjoint transient sensitivity computation in piecewise linear simulation

ABSTRACT

This paper presents a general method for computing transient sensitivities using the adjoint method in event driven simulation algorithms that employ piecewise linear device models. Sensitivity information provides first order assessment of circuit variability with respect to design variables and parasitics. This information is particularly useful for noise stability analysis, timing rule generation, and circuit optimization. Techniques for incorporating adjoint transient sensitivity into ACES, a general piecewise linear simulator, are presented. Sensitivity computation includes algorithms to handle instantaneous charge redistribution due to the discontinuous conductance models of the piecewise linear elements, and the loss of simulation accuracy due to the non-monotonous responses in autonomous adjoint circuits with non-zero initial conditions. Results demonstrate the efficiency and accuracy of the proposed techniques.

REFERENCES

• 1: A. Devgan and R. A. Rohrer. "Adaptively Controlled Explicit Simulation,'* IEEE Trans. Computer-Aided Design. Val. 13. pp. 746-762, June 1994.
• 2: S.W. Director and R. A. Rohrer. "The Generalized Adjoint Network and Network Sensitivities." ZEEE Tran. Circuit Theory, vol. 16, pp. 3 18-323. August 1969.
• 3: D.A. Hocevar, P, Yang. T. N. Trick, and B. D. Epler. "Transient Sensitivity Computation for MOSFET Circuits."IEEE Trans. Computer-Aided Design, vol. 4, pp. 609-620, Oct. 1985.
• 4: P. Feldmann. T. V. Nguyen, S. W. Director. and R. A. Rohrer, "Sensitivity Computation in Piecewise Approximate Circuit Simulation," IEEE Trans. Computer-Aided Design, vol. 10. pp. 171-183, Feb. 1991.
• 5: C-J Chen and W-S Feng, "Relaxation-Based Transient Sensitivity Computation for MOSFET Circuits,.' IEEE Trans. Computer-AidedDe, ign, vol. 14. pp. 173-185, Feb. 1995.
• 6: T.V. Nguyen. P. Feldmann, S. W. Director. and R. A. Rohrer. "SPECS Simulation Validation with Efficient Transient Sensitivity Computation." Proc. ICCAD, 1989, pp. 252-255.

INDEX TERMS

Primary Classification:
  B. Hardware
  B.7 INTEGRATED CIRCUITS
      B.7.1 Types and Design Styles
          Subjects: VLSI (very large scale integration)

Additional Classification:
  B. Hardware
  B.7 INTEGRATED CIRCUITS
      B.7.2 Design Aids
          Subjects: Simulation
  B.8 Performance and Reliability

  C. Computer Systems Organization

  G. Mathematics of Computing
  G.4 MATHEMATICAL SOFTWARE
      Subjects: Algorithm design and analysis

  J. Computer Applications

General Terms:
Algorithms, Design, Measurement, Performance, Theory

Keywords:
ISM frequency band, RF CMOS, digital radio, spread spectrum communication, transceiver