Low Power CMOS OTA Design for Biomedical Applications

Low Power CMOS OTA Design for Biomedical Applications

M V Sai Meena

1. ech Scholar Department of ECE, AVNIET,

   Hyderabad.

   Somashekhar Malipatil Assistant Professor Department of ECE, AVNIET,

   Hyderabad.

   D Santhosh Kumar Assistant Professor Department of ECE, AVNIET,

   Hyderabad

   Abstract In this paper designing of MOS Transistors in two stages OTA has been done and simulated in 120nm technology. Layout has done using Microwind 2 and schematic is designed using DSCH software. A comparison has been made between scaled voltage supply and power consumption. The simulation results show that the designed two stages OTA achieves the low power consumption

   Keywords Operational transconductance amplifier (OTA), CMOS, Power consumption, 120nm Technology, Microwind 2, DSCH 2.

   1. INTRODUCTION

      Operational transconductance amplifier is the differential amplifier with single stage. OTA is having two high input impedance nodes. OTA is a device which converts input voltage to output current. Primarily these are called voltage to current amplifiers. It is denoted as gm. The output current is the difference between the inverting and non inverting voltages is shown in the equation 1.

      Io=gm(V+-V-) 1

      OTA are mainly used in video applications, intermediate frequency, radio frequency. Other additional applications for OTA are sample and hold, timers, multiplexers broadcast equipment and high speed data acquisition devices.

      Fig.1 CMOS Differential Amplifier

      operational transconductance amplifier

      In this paper the two stage transconductance amplifier is designed for lower applications like suitable for biomedical applications by using voltage scaling. In the

      first stage the difference amplifier has designed as shown in

      fig.1. Fig 2. Differential Amplifier Layout

      Fig 3. Differential amplifier 3D process view

      Fig 4. CMOS OTA

      Fig 5. OTA Layout

      Fig 6. OTA 3D process view

      In this operational transconductance amplifier supply voltage is reduced to 1.2V.

   2. RESULTS

      Fig 7. Ids versus Vds characteristics of OTA

      Fig 8. Voltage versus current

   3. CONCLUSION

In this design low power Operational transconductance amplifier has designed by using voltage scaling down and observed reduction in power consumption as follows when supply voltage 2.5V, 1.8v and 1.2 V applied, the power consumption is 0.512mW, 0.21mW, 0.15mW respectively.

F

ig 9. Amplifier simulation waveform at Vdd 2.5V

Fig 10. Amplifier simulation waveform at Vdd 1.8V

Fig 11. Amplifier simulation waveform at Vdd 1.2V Table 1: Power analysis

Graph 1. Power analysis

REFERENCES

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3. G. Palmisano, G. Palumbo and S. Pennisi, Design Procedure for Two- Stage CMOS Transconductance Operational Amplifiers: A Tutorial, Analog Integrated Circuits and Signal Processing, 27, 179189, 2001.

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