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Parameters of OP-AMP M.S.P.V.L Polytechnic College, Pavoorchatram. www.ustudy.in Circuit Symbols of OP-AMP www.ustudy.in Parameters of OP-AMP Input offset voltage Input offset current Input BIAS current Input capacitance Ci Common mode rejection ratio Supply voltage rejection ratio Slew rate Gain bandwidth product Large signal voltage gain Output voltage swing Differential input resistance Ri www.ustudy.in Input offset voltage Input offset voltage is the voltage that must be applied between the two input terminals of an op-amp to null the output. Typical value of 741 IC is 6mV dc. www.ustudy.in Input offset voltage www.ustudy.in Input offset current The algebraic difference between the current in the inverting and non inverting terminal is known as the input offset current Iio. As the matching between two terminals increases,the difference between IB1 and IB2 become smaller. Typical value for 741 IC is 200mA(max). www.ustudy.in Input offset current www.ustudy.in Input BIAS current IB is the average current flows in the Inverting and Non-Inverting terminal of OP-AMP. IB = (IB1 + IB2 )/2 Typical value for 741 is 500mA www.ustudy.in Input BIAS current www.ustudy.in Large Signal voltage Gain It is the ratio of the output voltage and the differential input voltage. A= Output voltage/Differential input = Vo/Vid Typical value for 741 IC is 200,000. www.ustudy.in Large Signal voltage Gain www.ustudy.in Output Voltage Swing This parameter indicates the values of positive and negative saturation voltage of the op- amp. For 741IC,it is +13 and -13V. www.ustudy.in Output Voltage Swing www.ustudy.in Differential Input Resistance Ri Differential input resistance Ri is the equivalent resistance that can be measured at either the inverting or non-inverting input terminals with the other terminal connected to ground. Typical value for 741 IC is 2 mega ohm. www.ustudy.in Differential Input Resistance Ri www.ustudy.in Input Capacitance Ci Input capacitance is the equivalent capacitance that can be measured at either the inverting or non-inverting input terminal with the other terminal connected to ground. Typical value for a 741 IC is 1.4 pF. www.ustudy.in Input Capacitance Ci www.ustudy.in Common Mode Rejection Ratio When the same voltage is applied to both the input terminals the voltage is called a common mode voltage Vcm and the opamp is said to be operating in the common mode configuration CMRR is defined as the ratio of the differential voltage gain to common mode gain. CMRR = Ad/Acm www.ustudy.in Common Mode Rejection Ratio www.ustudy.in Supply Voltage Rejection Ratio The change in an op-amps input offset voltage Vio caused by variations in the supply voltage is called the SVRR. It is expressed in microvolts per volt or in decibels. SR= ΔVio/ΔV Typical value for a 741IC is 150μV/V www.ustudy.in Supply Voltage Rejection Ratio www.ustudy.in Slew Rate Slew rate is defined as the maximum rate of change of output voltage per unit of time and is expressed as volt per micro second. SR=(|dVo|/|ds|)max ie V\μs www.ustudy.in Slew Rate www.ustudy.in Gain Bandwidth Product The gain bandwidth product(GB) is the bandwidth of the op- amp when the voltage gain is 1. Typical value for 741 IC is 1MHz. www.ustudy.in Gain Bandwidth Product www.ustudy.in The End …… Thank You …… www.ustudy.in