Information Technology Reference
In-Depth Information
A Combined CMOS Reference Circuit
with Supply and Temperature Compensation
Madhusoodan Agrawal and Alpana Agarwal
Thapar University, Patiala, India
vashu13jan@gmail.com, alpana@thapar.edu
Abstract.
In this paper, a Combined CMOS Reference Circuit is proposed in
UMC 180 nm standard CMOS Process. It consists of a start-up circuit, a current
generator, and a voltage generator. This circuit achieves a nominal value of
50.11 µA and 776.4 mV for current and voltage respectively, from a 1.8 V
supply voltage. The line sensitivity of 285 ppm/V and 347 ppm/V for current
and voltage is achieved respectively, under the ±10 % variation in supply
voltage. The temperature coefficient for current and voltage are 93 ppm/°C and
295 ppm/°C respectively in temperature ranges −40 °C to 125 °C.
Keywords:
Beta Multiplier, Current reference, Oscillators, Temperature
compensation, Voltage Reference.
1
Introduction
In most Mixed Signal circuits, Reference Circuit is a key component in the design of
many analog and mixed signal applications including PLL, Analog-to-Digital Conver-
tor (ADC), Voltage Regulators, Digital to Analog Convertor (DAC) and many other
measurement and control systems. The Reference Circuit is required to be insensitive
to supply and temperature variations.
Many current reference and voltage reference circuits have been reported [1
3].
The references are used individually for generating fixed value of current or voltage
for the particular use in mixed signal design [4, 5] . These individual current and vol-
tage reference circuits fail, when there is a requirement of both fixed current and vol-
tage in any circuit,
e.g.
a oscillator circuit requires both current and voltage reference.
So the main aim of this work is to offer a design methodology for a combined refer-
ence circuit, which provides both current as well as voltage with a better supply and
temperature independency.
The paper is organized as follows. Section 2 presents about the basic building
blocks of the proposed combined reference circuits. Section 3 describes the simula-
tion and various results of proposed reference circuit, which is followed by discussion
and conclusions in Section 4.
−
