Research Article
Bus Implementation Using New Low Power PFSCL
Tristate Buffers
Neeta Pandey,
1
Bharat Choudhary,
1
Kirti Gupta,
2
and Ankit Mittal
3
1
Department of Electronics and Communication Engineering, Delhi Technological University, Delhi 110042, India
2
Department of Electronics and Communication Engineering, Bharati Vidyapeeth’s College of Engineering, Delhi 110063, India
3
Department of EEE/E&I, Birla Institute of Technology, Pilani University, K. K. Birla Goa Campus, Goa 403726, India
Correspondence should be addressed to Kirti Gupta; kirtigupta22@gmail.com
Received 30 November 2015; Accepted 24 January 2016
Academic Editor: Stephan Giſt
Copyright © 2016 Neeta Pandey et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
is paper proposes new positive feedback source coupled logic (PFSCL) tristate buffers suited to bus applications. e proposed
buffers use switch to attain high impedance state and modify the load or the current source section. An interesting consequence
of this is overall reduction in the power consumption. e proposed tristate buffers consume half the power compared to the
available switch based counterpart. e issues with available PFSCL tristate buffers based bus implementation are identified and
benefits of employing the proposed tristate buffer topologies are put forward. SPICE simulation results using TSMC 180 nm CMOS
technology parameters are included to support the theoretical formulations. e performance of proposed tristate buffer topologies
is examined on the basis of propagation delay, output enable time, and power consumption. It is found that one of the proposed
tristate buffer topology outperforms the others in terms of all the performance parameters. An examination of behavior of available
and the proposed PFSCL tristate buffer topologies under parameter variations and mismatch shows a maximum variation of 14%.
1. Introduction
Conventional CMOS circuits are widely used in digital
integrated circuit design due to their design ease, high
packing density, and negligible static power consumption
[1]. e large switching noise generation in CMOS circuits
restricts their use in applications pertaining to mixed-signal
environment [2, 3]. Research efforts are, therefore, made
towards exploring alternate low-noise logic styles. ese logic
styles are based on the current steering principle [4–7] and
draw a constant current from power supply and generate low
switching noise in comparison to CMOS logic style. Positive
feedback source coupled logic (PFSCL) style [6–10] is one
among these styles that works on current steering principle
and is used in high speed designs.
is paper addresses implementation of PFSCL busses
employed to transfer data between various peripherals inside
the microprocessors based systems in mixed-signal envi-
ronments. A typical bus system has many tristate buffers
attached to a common node. e study of PFSCL tristate
buffers/inverters reveals that only two topologies are available
[11]. ese topologies use either a switch or a sleep transistor
to attain the tristate behavior. e suitability of the sleep
transistor and the switch transistor based PFSCL tristate
buffers [11] in bus system implementation is investigated and
the drawbacks are identified. New PFSCL tristate buffers for
this purpose are presented in this work.
e paper is organized in six sections including the intro-
ductory one. A brief review of available PFSCL tristate buffers
is presented in Section 2. Design issues in implementing bus
system using the available tristate buffers are identified in
Section 3. ereaſter, the new PFSCL tristate buffer topologies
are presented in Section 4. eir performance comparison
and suitability in bus implementation are demonstrated
through SPICE simulations by using TSMC 180 nm CMOS
technology parameters in Section 5. e impact of parameter
variations and the effect of parameter mismatch are also
studied for the proposed topologies. Lastly, the paper is
concluded in Section 6.
Hindawi Publishing Corporation
Active and Passive Electronic Components
Volume 2016, Article ID 4517292, 8 pages
http://dx.doi.org/10.1155/2016/4517292