International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 11 Issue: 06 | Jun 2024
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p-ISSN: 2395-0072
Design and Performance Analysis of CMOS Voltage Controlled Oscillator (VCO) in Static CMOS 45 nm Technology Ajay J, Hemanth Joshi, Rajath Nayaka B M and B P Harish Department of Electronics and Communication Engineering, University Visvesvaraya College of Engineering, Bangalore University, Bangalore, India
------------------------------------------------------------------------***------------------------------------------------------------------------Abstract: This paper presents a relative study among different topologies of Ring Oscillator based Voltage Controlled Oscillator (VCO) on the basis of different parameters like centre frequency, tuning range, frequency stability, power dissipation and linearity etc. All the design has been done in 45 nm Static CMOS technology and are subsequently compared on various parameters. An inherent idea of the given performance parameters has been realized by the comparative study. The comparative data shows that VCO with both NMOS & PMOS control devices along with
translate into performance variability. Densely packed devices result in parasitic capacitances leading to undesirable signal interference and distortion. In the domain of VLSI design the selection of a linear and wide range voltage-controlled oscillator for various RF, Biomedical, Clock recovery circuits and other applications is always a challenging work for Electronics Engineers. An oscillator is an electrical autonomous system which generates a periodic oscillating frequency signal depending on its input voltage. VCO is the main component in many RF circuits and is the heart of Phase Lock Loop system, Clock recovery circuit and Frequency Integrated circuits, so it is very vital to select the suitable VCO design. Frequency, amplitude and noise level should be controlled for many of the applications.
complementary Vctr has the best trade-off between power dissipation and tuning range. In this study the topology of VCO with complementary control voltages exhibits tuning range of 0-20 GHz and power dissipation less than 1.5mW thus eliciting Ring oscillator based VCO is best in terms of power consumption. Simulations are carried out using the LTSpice simulator in a 45 nm standard process. Keywords: Voltage Controlled Oscillator (VCO), Static CMOS, Tuning range, Power consumption.
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Oscillators can be divided into two categories; Firstly, the LC oscillator which is composed of the active devices, coupled with LC resonant circuit. Secondly, the loop ring oscillator which is composed of delayed cascade units with positive feedback. The important requirements of VCO are High gain, wide tuning range, low power consumption and high signal to noise ratio.
Introduction
In today’s IC industry a good understanding of semiconductor process and devices is essential, as process to device to circuit domains are tightly coupled, for quality of analog / digital designs. In digital designs MOS transistors are considered as simple switches but in analog designs detailed understanding of the device is required because of its multiple roles as amplifying device, capacitor, switch etc. and this implication of the second order effects on the performance of circuit. Further, with the advent of device scaling into nanometer regime, implications of non-ideal effects become significant and the circuit designer has to decide on the selection of second order effects to be considered for design. At nanoscale integration, the CMOS technology has become a technology of choice for analog circuit design in a mixed signal environment.
The design of a Voltage Controlled Oscillator involves many trade-offs between area, speed, power, and application domains. These problems and a comparative study of different ring oscillator designs is midst interest in this paper. The performance of different circuits has been comparatively analysed through simulation results in 45nm CMOS Technology using LTSpice
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2.1 Ring Oscillator Design: The design of the ring oscillator can be done using three inverters. The three-stage ring oscillator with 3 inverter stages connected in series to form a positive feedback system to provide sufficient gain to support sustained oscillations. The frequency of oscillations is given in Eq. (1.1). f =1 τ………………...… (1.1)
Since all the basic devices in an IC respond to continuous time stimulus, analog design forms the foundation for all IC designs. Modern IC technology presents many design challenges. There is significant variability in the manufacturing process for advanced technology nodes. The actual operation of the large number of devices on advanced ICs also causes variability. This variability manifests as changes in the device threshold voltage, supply voltage, operating temperature, which in turn
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Simulation Methodology
where τ = time delay for single inverter, n = number of inverters in the oscillator.
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