1 / 34

ELEC 5270/6270 Spring 2011 Low-Power Design of Electronic Circuits Adiabatic Logic

ELEC 5270/6270 Spring 2011 Low-Power Design of Electronic Circuits Adiabatic Logic. Vishwani D. Agrawal James J. Danaher Professor Dept. of Electrical and Computer Engineering Auburn University, Auburn, AL 36849 vagrawal@eng.auburn.edu

alatoya
Download Presentation

ELEC 5270/6270 Spring 2011 Low-Power Design of Electronic Circuits Adiabatic Logic

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. ELEC 5270/6270 Spring 2011Low-Power Design of Electronic CircuitsAdiabatic Logic Vishwani D. Agrawal James J. Danaher Professor Dept. of Electrical and Computer Engineering Auburn University, Auburn, AL 36849 vagrawal@eng.auburn.edu http://www.eng.auburn.edu/~vagrawal/COURSE/E6270_Spr11/course.html ELEC6270 Spring 11, Lecture 8

  2. Examples of Power Saving and Energy Recovery • Power saving by power transmission at high voltage: • 1000W transmitted at 100V, current I = 10A • If resistance of transmission circuit is 1Ω, then power loss = I2R = 100W • Transmit at 1000V, current I = 1A, transmission loss = 1W • Energy recovery from automobile braking: • Normal brake converts mechanical energy into heat • Instead, the energy can be stored in a flywheel, or • Converted to electricity to charge a battery ELEC6270 Spring 11, Lecture 8

  3. Reexamine CMOS Gate V2/ Rp V Most energy dissipated here i2Rp i = Ve–t/RpC/Rp v(t) Power V×i = V2e–2t/RpC/ Rp v(t) V C v(t) 3RpC 0 Time, t Energy dissipation per transition = Area/2 = C V 2/ 2 ELEC6270 Spring 11, Lecture 8

  4. Charging with Constant Current V(t) i2Rp i = constant it/C V v(t) = it/C C2V2Rp/T2 Output voltage, v(t) Power C 0 0 T=CV/i Time, t Time (T) to charge capacitor to voltage V v(T) = V = iT/C, or T = CV/i Current, i = CV/T Power = i2Rp = C2V2Rp/T2 Energy dissipation = Power × T = (RpC/T) CV2 ELEC6270 Spring 11, Lecture 8

  5. Or, Charge in Steps 0→V/2→V i2Rp i = Ve–t/RpC/2Rp V2e–2t/RpC/4Rp v(t) v(t) V2/4Rp V C v(t) Power V/2 0 3RpC 6RpC Energy = Area = CV2/8 Time, t Total energy = CV2/8 + CV2/8 = CV2/4 ELEC6270 Spring 11, Lecture 8

  6. Energy Dissipation of a Step Voltage step = V/N T E = ∫ V2e–2t/RpC/(N2Rp) dt 0 = [CV2/(2N2)] (1 – e–2T/RpC) ≈ CV2/(2N2) for large T ≥ 3RpC ELEC6270 Spring 11, Lecture 8

  7. Charge in N Steps Supply voltage 0 → V/N → 2V/N → 3V/N → . . . NV/N Current, i(t) = Ve–t/RpC/NRp Power, i2(t)Rp = V2e–2t/RpC/N2Rp Energy = N CV2/2N2 = CV2/2N → 0 for N → ∞ Delay = N × 3RpC → ∞ for N → ∞ ELEC6270 Spring 11, Lecture 8

  8. Reexamine Charging of a Capacitor R t = 0 v(t) i(t) C V Charge on capacitor, q(t) = C v(t) Current, i(t) = dq(t)/dt = C dv(t)/dt ELEC6270 Spring 11, Lecture 8

  9. i(t) = C dv(t)/dt = [V – v(t)] /R dv(t) V – v(t) ─── = ───── dt RC dv(t) dt ∫───── = ∫ ──── V – v(t) RC – t ln [V – v(t)] = ── + A RC Initial condition, t = 0, v(t) = 0 → A = ln V – t v(t) = V [1 – exp(───)] RC ELEC6270 Spring 11, Lecture 8

  10. – t v(t) = V [1 – exp(── )] RC dv(t) V – t i(t) = C ─── = ── exp(── ) dt R RC ELEC6270 Spring 11, Lecture 8

  11. Total Energy Per Charging Transition from Power Supply ∞∞ V 2 – t Etrans = ∫ V i(t) dt = ∫ ── exp(── ) dt 00 R RC = CV2 ELEC6270 Spring 11, Lecture 8

  12. Energy Dissipated per Transition in Resistance ∞ V 2 ∞ –2t R ∫ i 2(t) dt = R ── ∫ exp(── ) dt 0 R20 RC 1 = ─ CV 2 2 ELEC6270 Spring 11, Lecture 8

  13. Energy Stored in Charged Capacitor ∞ ∞ – t V – t ∫ v(t) i(t) dt = ∫ V [1– exp(── )]─ exp(── ) dt 00 RC R RC 1 = ─ CV 2 2 ELEC6270 Spring 11, Lecture 8

  14. Slow Charging of a Capacitor R t = 0 v(t) i(t) C V(t) Charge on capacitor, q(t) = C v(t) Current, i(t) = dq(t)/dt = C dv(t)/dt ELEC6270 Spring 11, Lecture 8

  15. i(t) = C dv(t)/dt = [V(t) – v(t)] /R dv(t) V(t) – v(t) ─── = ───── dt RC dv(t) dt ∫────── = ∫ ──── V(t) – v(t) RC ELEC6270 Spring 11, Lecture 8

  16. Effects of Slow Charging Voltage across R Voltage V(t) v(t) t ELEC6270 Spring 11, Lecture 8

  17. Constant Current Is Optimum I(t) R t = [0,T] V C ELEC6270 Spring 11, Lecture 8

  18. Average and Instantaneous Current Let T be the time to charge C to voltage V T Average current : (1/T) ∫ I(t) dt = I0 0 Instantaneous current: I(t) = I0 + i(t) T Where ∫ i(t) dt = 0 0 ELEC6270 Spring 11, Lecture 8

  19. Energy Dissipation TT E = R ∫ I2(t) dt = R ∫ [I0 + i(t)]2 dt 0 0 T = R ∫ [I02 + 2I0i(t) + i2(t)] dt 0 T T = RI02T + 2RI0 ∫ i(t) dt + R ∫ i2(t) dt 0 0 T = RI02T + 0 + R ∫ i2(t) dt ≥ RI02T 0 = RI02T, minimum value, when i(t) = 0, i.e., I(t) = I0 ELEC6270 Spring 11, Lecture 8

  20. Minimum Energy For a constant current I0, Charging time, T = CV/I0 Emin = RCVI0 ELEC6270 Spring 11, Lecture 8

  21. References • C. L. Seitz, A. H. Frey, S. Mattisson, S. D. Rabin, D. A. Speck and J. L. A. van de Snepscheut, “Hot-Clock nMOS,” Proc. Chapel Hill Conf. VLSI, 1985, pp. 1-17. • W. C. Athas, L. J. Swensson, J. D. Koller, N. Tzartzanis and E. Y.-C. Chou, “Low-Power Digital Systems Based on Adiabatic-Switching Principles,” IEEE Trans. VLSI Systems, vol. 2, no. 4, pp. 398-407, Dec. 1994. ELEC6270 Spring 11, Lecture 8

  22. A Conventional Dynamic CMOS Inverter V P E P E P E CK vin v(t) CK v(t) C vin ELEC6270 Spring 11, Lecture 8

  23. Adiabatic Dynamic CMOS Inverter P E P E P E P E V 0 CK vin v(t) v(t) vin C Vf + V-Vf 0 CK A. G. Dickinson and J. S. Denker, “Adiabatic Dynamic Logic,” IEEE J. Solid-State Circuits, vol. 30, pp. 311-315, March 1995. ELEC6270 Spring 11, Lecture 8

  24. Cascaded Adiabatic Inverters vin CK1 CK2 CK1’ CK2’ input CK1 CK2 CK1’ CK2’ evaluate precharge hold ELEC6270 Spring 11, Lecture 8

  25. Complex ADL Gate AB + C A C Vf < Vth B CK A. G. Dickinson and J. S. Denker, “Adiabatic Dynamic Logic,” IEEE J. Solid-State Circuits, vol. 30, pp. 311-315, March 1995. ELEC6270 Spring 11, Lecture 8

  26. Clocks EVAL. HOLD EVAL. HOLD VDD  0 VDD  0 ELEC6270 Spring 11, Lecture 8

  27. Quasi-Adiabatic Logic Design • Possible Cases: • The circuit output node X is LOW and the pMOS tree is turned ON: X follows  as it swings to HIGH (EVALUATE phase) • The circuit node X is LOW and the nMOS tree is ON. X remains LOW and no transition occurs (HOLD phase) • The circuit node X is HIGH and the pMOS tree is ON. X remains HIGH and no transition occurs (HOLD phase) • The circuit node X is HIGH and the nMOS tree is ON. X follows  down to LOW. ELEC6270 Spring 11, Lecture 8

  28. A Case Study K. Parameswaran, “Low Power Design of a 32-bit Quasi-Adiabatic ARM Based Microprocessor,” Master’s Thesis, Dept. of ECE, Rutgers University, New Brunswick, NJ, 2004. ELEC6270 Spring 11, Lecture 8

  29. Quasi-Adiabatic 32-bit ARM Based Microprocessor Design Specifications • Operating voltage: 2.5 V • Operating temperature: 25oC • Operating frequency: 10 MHz to 100 MHz • Leakage current: 0.5 fAmps • Load capacitance: 6X10-18 F (15% activity) • Transistor Count: ELEC6270 Spring 11, Lecture 8

  30. Technology Distribution • Microprocessor has a mix of static CMOS and Quasi-adiabatic components Quasi-Adiabatic Static CMOS • ALU • Adder-subtractor • unit • Barrel shifter unit • Booth-multiplier • unit • Control Units • ARM controller unit • Bus control unit • Pipeline Units • ID unit • IF unit • WB unit • MEM unit ELEC6270 Spring 11, Lecture 8

  31. Power Analysis ELEC6270 Spring 11, Lecture 8

  32. Power Analysis (Cont’d.) ELEC6270 Spring 11, Lecture 8

  33. Area Analysis ELEC6270 Spring 11, Lecture 8

  34. Summary • In principle, two types of adiabatic logic designs have been proposed: • Fully-adiabatic • Adiabatic charging • Charge recovery: charge from a discharging capacitor is used to charge the capacitance from the next stage. • W. C. Athas, L. J. Swensson, J. D. Koller, N. Tzartzanis and E. Y.-C. Chou, “Low-Power Digital Systems Based on Adiabatic-Switching Principles,” IEEE Trans. VLSI Systems, vol. 2, no. 4, pp. 398-407, Dec. 1994. • Quasi-adiabatic • Adiabatic charging and discharging • Y. Ye and K. Roy, “QSERL: Quasi-Static Energy Recovery Logic,” IEEE J. Solid-State Circuits, vol. 36, pp. 239-248, Feb. 2001. ELEC6270 Spring 11, Lecture 8

More Related