International Research Journal of Engineering and Technology (IRJET)
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Volume: 10 Issue: 08 | Aug 2023
p-ISSN: 2395-0072
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Design and Implementation of a Dual Stage Operational Amplifier Saumya Mishra1 1M.Tech Scholar, Department of ECE, Indira Gandhi Delhi Technical University for Women, Delhi, India
---------------------------------------------------------------------***--------------------------------------------------------------------applications. For instance, a modern op-amp must be able to Abstract - In this paper, we have used Miller Compensation
deliver single ended output swings of up to 0.8 V while operating with input voltages as low as 0.9 V. When this happens, we turn to "two-stage" operational amplifiers, in which the first stage is responsible for providing high gain and the second stage provides large swings. A two-stage arrangement isolates the gain and swing requirements as opposed to cascode op amps [7].
Technique to amplify the gain of a 2-stage Op-Amp. Below mentioned procedure follows the technique of developing a theoretical design followed by carrying out a simulation process by presuming some values for a particular operational situation (we’ve taken help of LTspice for that). The resultant CMOS Op-Amp was tested in a simulated parameter of VDD=1.8V in order to test the accuracy of theoretically concluded numbers. The CMOS technology used was 180nm with the help of LTspice tool. In the above mentioned environment; the following key factors were taken into observation: gain margin, phase margin, Output Power dissipation, output Noise and unity gain bandwidth.
There has been multiple research that produced a >140dB gain using the multi-stage amplifier technology, which has been around for a while. The stability of the opamps may be compromised by the close spacing of the poles caused by cascading many stages.
Key Words: Gain Margin, Phase Margin, Gain Bandwidth, Miller Compensation
when we observe the second order system’s time response with step input, we see that larger phase margin results in reduced oscillations in the output signal[12][13]. we prefer to have ringing as minimum as possible. A minimum of 45 degrees phase margin is desirable and a 60 degree PM is mostly preferred [12].
1.INTRODUCTION The road for the expanding market of sophisticated electronics applications in mobiles and sensor applications was created by the recent development in CMOS scaling. The integration of complicated functionalities on a single chip (such as a SOC (System on Chip)), along with ongoing increases in operating speed and decreases in system power consumption, is what drives scaling.[1] Transistor dimensions are getting smaller as a result of improvements in CMOS manufacturing techniques [1]. The advantages of adopting smaller dimension transistors typically result in lower power consumption, smaller device sizes, and higher performance at high frequencies. Transconductance and output resistance, two crucial analog properties of a transistor, will decrease as a result of the use of tiny CMOS technologies.
Fig -1: Time Response depiction of a second order System corresponding to different Phase Margins
Analog circuits frequently employ operational amplifiers (op-amps) with negative feedback to create amplifiers with a variety of desirable characteristics, including steady gain, good linearity, and low output impedance [2]. However, the negative feedback's significant phase lag causes a stability (STB) problem. The STB of the amplifier has been improved using a variety of approaches [3]-[5].
Frequency correction must be carried out to improvise the stability and provide proper transient step responsiveness. Miller and cascode compensations are well-known approaches. Miller compensation is well known for its ability to increase bandwidth via pole splitting phenomenon. We will be employing miller compensation in our dual-stage opamp and observe the results with high gain and improved phase margin. Though miller compensation is used to enhance the gain bandwidth product, complexity has also risen as a result of interims of extra amplifier stages and capacitors. The stability is compromised by the right half
The gain of a single-stage opamp is derived by multiplying transconductance with the output impedance. The gain and other crucial parameters such as output swing, gain bandwidth, etc. offered by various topologies of a single-stage opamp such as Single stage Common Source Amplifier, Cascode Amplifier, etc. are insufficient for several
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