Device-Circuit Interactions in Oxide TFT Circuits and Systems
Arokia Nathan, Xiang Cheng, Sungsik Lee
1
Electrical Engineering Div, Engineering Dept, Cambridge University, Cambridge
CB3 0FA, UK
Reza Chaji, IGNIS Innovation Inc., Waterloo, ON, N2V 2C5 Canada
E-mail:
The oxide TFT technology continually evolves to produce devices with better
performance, such as higher mobility, steeper subthreshold slope and lower V
T
. However,
practical circuits and applications based on oxides gets somewhat constrained due to issues
related to non-uniformity, illumination-induced instability, and temperature dependence.
While the transistor performance is still distant from the ubiquitous integrated circuit
MOSFET technology, which limits the design capability on such devices, it is imperative to
consider device-circuit interactions when designing circuits and applications with transistors
of poorer performance and a higher degree of non-ideality as compared with the CMOS
technology.
In this paper, we will discuss device-circuit interactions in two aspects. Firstly, we will
discuss the impact of intrinsic device properties on circuit performance. Specifically, we
investigate the current sensitivity on temperature and non-uniformity of TFTs, in which we
systematically point out how the design of the circuit should be optimized with respect to the
desired performance. The intrinsic device limitations provide a guideline of whether the
device-circuit interaction would pose serious issues that should be systematically considered
from the standpoint of geometric and parametric variations. From the analyzed sensitivity of
the key parameter set of the TFT parameters, we can establish a better understanding of how
to improve the transistor performance to reduce these interactions.
Secondly, we will discuss several application examples to show how device-circuit
interactions should be handled in specific applications as these will likely to have strict
requirements on some transistor parameters while allowing a more relaxed tolerance on
others. This provides essential insight on how compensation can be deployed at the same
time obtaining an optimized circuit performance. Specifically, we will discuss the
device-circuit interactions in displays, sensors and analog front-end circuits (i.e. sensor
interfaces) to show how device-circuit interactions should be handled and how the
compensation methods can be implemented.
PO 6
-77-
