Vol.:(0123456789) 1 3
Journal of Computational Electronics
https://doi.org/10.1007/s10825-019-01362-y
Dual‑chirality GAA‑CNTFET‑based SCPF‑TCAM cell design for low
power and high performance
S. V. V. Satyanarayana
1
· Singh Rohitkumar Shailendra
1
· V. N. Ramakrishnan
1
· Sridevi Sriadibhatla
1
© Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
Ternary content-addressable memory (TCAM) is a type of associative memory used in many applications for high-speed
data searching. We present herein a gate-all-around (GAA) carbon nanotube feld-efect transistor (CNTFET)-based self-
controlled TCAM cell design with a precharge-free match line. We compare the power–delay product (PDP) and static noise
margin between the GAA-CNTFET-based traditional and proposed TCAM cell designs at the 11-nm technology node with a
supply voltage of 0.8 V. The simulations are performed using the Virtuoso tool for diferent parameter values with the Stan-
ford University GAA-CNTFET model. The simulation results show that, compared with the traditional design, the proposed
design exhibits a signifcant reduction in power by 51.30%, delay by 17.16%, and PDP by 59.66% for a chiral vector of (20,
16, 0) with two channels. It is observed that the best chirality for the proposed design is (14, 20, 0) for a single channel, but
(16, 16, 0) and (20, 16, 0) for a dual channel in terms of power, delay, stability, and PDP.
Keywords Delay · Diameter · GAA CNTFET · Low power · Match/miss · SCPF · TCAM
1 Introduction
According to the recommendations of the International
Technology Roadmap for Semiconductors (ITRS), there
is a substantial need for transistors with channel length of
less than 32 nm [1]. However, below 32 nm, metal oxide
semiconductor (MOS) technology sufers from high leak-
age currents, mobility degradation, and threshold voltage
instability, as well as becoming sensitive to process–volt-
age–time (PVT) variations [2, 3]. To address these issues
at the nanoscale, an alternative to MOS transistors must
therefore be pursued. Devices such as fn-based feld-efect
transistors (FinFETs) driven by Intel, fully depleted silicon-
on-insulator (FD-SOI) technology led by ST Microelectron-
ics, carbon nanotube feld-efect transistors (CNTFETs) lead
by IBM, as well as the resonant tunnelling diode (RTD) and
single-electron transistor (SET) are some of devices that
have been introduced to replace complementary (C)MOS
transistors. The CNTFET is one of the promising candidates
for application beyond the 32-nm node due to its properties
such as high mobility via ballistic transport, high mechanical
and thermal stability, high resistance to electromigration,
high transconductance, superior subthreshold slope, superior
threshold voltage, high current density, high I
ON
/I
OFF
ratio,
high switching reliability, high-temperature resistance, and
strong covalent bonding [4, 5].
This paper presents a compact circuit-compatible model
for the intrinsic channel region of the CNTFET. The mod-
eling approach and methodology described in this paper are
generally applicable to any one-dimensional (1-D) device.
This model is valid for a wide range of CNTFETs with chi-
rality and diameter varying from 0.2 to 2 nm, with either
semiconductor or metallic nature. This model includes the
quantum confnement efects in both the axial and circum-
ferential directions. To make it compatible with digital
and analog applications, a dynamic gate capacitance net-
work is implemented to describe the real-time dynamic
response. The model includes channel elastic scattering,
the doped source/drain region, the Schottky barrier resist-
ance, multiple CNTs per device, and other devices/circuits.
The GAA CNTFET model used in the simulation is based
on the SPICE-compatible Verilog-A model developed by
Stanford University. In particular, the model describes an
enhancement-mode MOSFET device with carbon nanotubes
* S. V. V. Satyanarayana
svvsatyanarayana8589@gmail.com
Singh Rohitkumar Shailendra
gudiyarohit2417@gmail.com
1
VIT University, Vellore 632014, India