Designing Asynchronous Circuits using NULL Convention Logic (NCL)

Author(s):  
Scott C. Smith ◽  
Jia Di
Author(s):  
Lac Truong Tri ◽  
Toi Le Thanh ◽  
Trang Hoang

The Null Convention Logic (NCL) based asynchronous circuits have eliminated the disadvantages of the synchronous circuits, including noise, glitches, clock skew, power, and electromagnetic interference. However, using NCL based asynchronous designs was not easy for students and researchers because of the lack of standard NCL cell libraries. This paper proposes a solution to design a semi-static NCL cell library used to synthesize NCL based asynchronous designs. This solution will help researchers save time and effort to approach a new method. In this work, NCL cells are designed based on the Process Design Kit 45nm technology. They are simulated at the different corners with the Ocean script and Electronic Design Automation (EDA) environment to extract the timing models and the power models. These models are used to generate a *.lib file, which is converted to a *.db file by the Design Compiler tool to form a complete library of 27 cells. In addition, we synthesize the NCL based full adders to illustrate the success of the proposed library and compare our synthesis results with the results of the other authors. The comparison results indicate that power and delay are improved significantly.


2007 ◽  
Vol 16 (01) ◽  
pp. 1-14
Author(s):  
TASKIN KOCAK ◽  
GEORGE R. HARRIS ◽  
RONALD F. DEMARA

In this paper, a novel architecture for self-timed analog-to-digital conversion is presented and designed using the NULL Convention Logic (NCL) paradigm. This analog-to-digital converter (ADC) employs successive approximation and a one-hot encoded masking technique to digitize analog signals. The architecture scales readily to any given resolution by utilizing the one-hot encoded scheme to permit identical logical components for each bit of resolution. The four-bit configuration of the proposed design has been implemented and assessed via simulation in 0.18-μm CMOS technology. Furthermore, the ADC may be interfaced with either synchronous or four-phase asynchronous digital systems.


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