Published on: **Mar 3, 2016**

- 1. DEPARTMENT OF TECHNOLOGY ELECTRONICS AND ELECTRICAL ENGINEERING Project topic – Design of Integrator Amplifier in Nanotechnology SUBJECT NAME- NANOTECHNOLOGY NAME OF STUDENT- RITESH KUMAR ROLL NO - EE15M04 STUDENT EMAIL -riteshkmr82@gmail.comp CONTACT NO- 9595541439 NAME OF LECTURER – MOHIT GODBOLE DUE DATE 19/10/2015
- 2. The Integrator Amplifier The Op-amp Integrator is an Operational Amplifier circuit that performs the mathematical operation of Integration that is we can cause the output to respond to changes in the input voltage over time as the op-amp integrator produces an output voltage which is proportional to the integral of the input voltage. The magnitude of the output signal is determined by the length of time a voltage is present at its input as the current through the feedback loop charges or discharges the capacitor as the required negative feedback occurs through the capacitor. Op-amp Integrator Op-amp Integrator - When a step voltage, Vin is firstly applied to the input of an integrating amplifier, the uncharged capacitor C has very little resistance and acts a bit like a short circuit allowing maximum current to flow via the input resistor, Rin as potential difference exists between the two plates. No current flows into the amplifiers input and point X is a virtual earth resulting in zero output. As the impedance of the capacitor at this point is very low, the gain ratio of Xc/Rin is also very small giving an overall voltage gain of less than one, (voltage follower circuit).
- 3. As the feedback capacitor, C begins to charge up due to the influence of the input voltage, its impedance Xc slowly increase in proportion to its rate of charge. The capacitor charges up at a rate determined by the RC time constant, ( τ ) of the series RC network. Negative feedback forces the op-amp to produce an output voltage that maintains a virtual earth at the op-amp’s inverting input. Since the capacitor is connected between the op-amp’s inverting input (which is at earth potential) and the op-amp’s output (which is negative), the potential voltage, Vc developed across the capacitor slowly increases causing the charging current to decrease as the impedance of the capacitor increases. This results in the ratio of Xc/Rin increasing producing a linearly increasing ramp output voltage that continues to increase until the capacitor is fully charged. At this point the capacitor acts as an open circuit, blocking any more flow of DC current. The ratio of feedback capacitor to input resistor ( Xc/Rin ) is now infinite resulting in infinite gain. The result of this high gain (similar to the op-amps open-loop gain), is that the output of the amplifier goes into saturation as shown below. (Saturation occurs when the output voltage of the amplifier swings heavily to one voltage supply rail or the other with little or no control in between). The rate at which the output voltage increases (the rate of change) is determined by the value of the resistor and the capacitor, “RC time constant“. By changing this RC time constant value, either by changing the value of the Capacitor, C or the Resistor, R, the time in which it takes the output voltage to reach saturation can also be changed for example.
- 4. Vout = output voltage from op amp integrator Vin = input voltage T = time after start of application of voltage in seconds R = resistor value in integrator in Ω C = capacitance of integrator capacitor in Farads c = constant of integration and in this case is the output starting voltage. The negative sign in the equation reflects the inversion resulting from the use of the inverting input of the op amp. Nano Scale Integrator Amplifier In the microscale integrator, I am trying to implement to the basic circuit components at microscale. For simplicity purpose trying to scale down each and energy circuit components one by one. Input voltage – Vin is the input voltage to circuit. The supply goes from Vin to the circuit. In the micro scale we are using carbon nanotubes as the power supply. Nano-scaffold for rechargeable lithium ion batteries that could help make circuit longer and smaller. The potential of manufactured sheets of aligned carbon nanotubes coated with silicon, a material with a much higher energy storage capacity than the graphite composites typically used in lithium ion batteries. Putting silicon into batteries can produce a huge increase in capacity—10 times greater. When the silicon-coated carbon nanotubes were aligned in one
- 5. direction like a layer of drinking straws laid end to end, the structure allowed for controlled expansion so that the silicon is less prone to pulverization. Resistor- Chromium oxide resistors is used in the Nano scale. Replacing chromium with oxygen affects both the numbers of electrons available to carry current and also the availability of paths for electrons to hop through the material Chromium oxide resistors in series with a quantum phase-slip nanowire Capacitor – Capacitors store their energy as an electrical charge. They can be charged rapidly, transferring energy. Capacitor energy storage is directly proportional to area and inversely proportional to the distance between the two layers, having an atom-wide separation between the layers
- 6. maximizes the power. Graphene sheets can be rolled to massively increase surface areas still within a limited volume. Carbon powder fused to aluminium foil to improve capacitor function. Operational Amplifier- Operational Amplifier are the fundamental building block of Analog electronics and more specifically Audio & Video systems, Analog to Digital Converters, Digital to Analog Converters, Active Filters, and RF systems CNTFETs are field-effect transistors using properly designed CNTs in the intrinsic channel region under the metal Gate between the Drain and the Source of a conventional FET. Its equivalent circuit is quite similar to the common Si-based MOSFET, but the CNT channels result in higher speed and less power consumption compared to nanoscale conventional MOSFET. One of the earliest CNTFET models was One-dimensional ballistic model which over- estimated the drain current. Op-amp Integrator (1000nm*600nm)