Characteristics of Ideal Operational Amplifier (Op-Amp)(English) скачать в хорошем качестве

Characteristics of Ideal Operational Amplifier (Op-Amp)(English)

IDEAL OPAMP CHARACTERISTICS The ideal op amp is a differential amplifier with infinite open-loop gain, infinite input impedance, zero output impedance, infinite bandwidth, and zero noise . Characteristics of Ideal opamp Infinite open loop gain Infinite input impedance Zero output impedance Infinite Bandwidth Zero offset voltage Infinite Common mode Rejection ratio(CMRR) Infinite Slew rate Zero Power supply rejection ratio 1. Infinite open loop gain It is gain with out feedback. Av=Vo/Vd It should be infinite to get maximum voltage of +Vcc or -Vcc Gain is high because it is designed to have high gain using multistage differential amplifiers 2. Infinite input impedance Due to infinite input impedance No current flows in the input terminals i.e Ib1=Ib2=0 The opamp can be driven by almost any source There is no loading of source 3. Zero output impedance Due to zero output impedance there will not any change in output voltage due to change in load current That means it can drive any number of loads or devices ideally. 4. Infinite Bandwidth Bandwidth is infinite means it can amplify all frequency signals from zero to infinite So the gain of amplifier remains constant from zero to infinite Therefore opamp can amplify dc as well as ac signals 5. Zero offset voltage Presence of small output voltage though input voltage is zero is called as offset voltage. Ideally offset voltage is zero means zero output voltage for zero input voltage i.e. V1=V2=0 6. Infinite CMRR The ratio of differential gain to common mode gain is defined as CMRR Infinite CMRR ensures zero common mode gain. So the common mode noise output is zero for ideal opamp. CMRR= Ad/Ac 7. Infinite Slew rate Infinite slew rate ensures that the changes in output voltage occur simultaneously with the changes in the input voltage. 8. Zero PSRR PSRR is the degree of dependence of output voltage on changes in power supply. PSRR=0 means the output voltage does not change with fluctuations in supply voltage.