SWITCHED OPERATIONAL AMPLIFIER BASED ANALOG FILTER DESIGN IN 18ONM CMOS TECHNOLOGY

Abstract

Choice of circuits at very low voltages becomes narrow for analog system design. Switched Capacitor technique is one of the best available for good quality analog circuits.. Due to device scaling and increase in demand for portable battery operated systems the need for very low voltage analog systems is increasing. Due to the limitations associated with the switches at very low voltages SC circuits cease to perform. On-chip voltage multiplier and the use of low threshold devices are some of the proposed techniques to be used with SC circuits at low voltages but none of them is effective. Switched opamp (SO) is the best suited technique for very low voltage SC circuits that replaces the problematic switches with switch able opamps. SO technique not only facilitates low voltage analog system operation but also reduces the power consumption of the analog system as the switch able opamps are in off state consuming zero power in one phase of the SC operation. Analog circuits that operate with low voltages and at low power are the areas that are growing attention. Switched Capacitor implementation of analog circuits with Switched Opamp technique enables low voltage and low power operation. The thesis work presents the design of SO at very low power supply of 1 V and demonstrates the power reduction of about 50%. The SO is simulated at 180nm technology with lv power supply using TSpice. A high Q SC biquad band pass filter is realized using SO technique at I V supply and 1 MHz clock. For this particular design there is an improvement in terms of power dissipation. This band pass filter finds applications in Radio Data System sub carrier detection