OpAmp-tutorial-1

6200002000 12 v 12 if i1 vinr1 1 2000 05 ma 05 av

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Unformatted text preview: RF = 2000 + 1 + AOL RoF = Ro = = R1/RF = 2000 / 20,000 = 0.1 0.1 20,000 = 2,000.05 1 + 400,000 60 = Note: is 0.09 because using 1.67 Note: m different formula than above different ICIS (Current Amplifier) Summary ICIS Not commonly done using operational amplifiers Not iL Load _ iin + 1 Possible Possible ICIS Operational Amplifier Application Application iin = iL Similar to the voltage Similar follower shown below: follower vin _ + _ + vin = vo + vO - Both these amplifiers have Both unity gain: unity Av = A i = 1 Voltage Follower VCIS (Transconductance Amplifier) Summary VCIS Voltage to Current Converter iL i1 vin R1 + Load Load i1 _ + _ OR vin _ + _ General Equations: iL = i1 = v1/R1 v1 = vin The transconductance, gm = io/vin = 1/R1 The Therefore, iL = i1 = vin/R1 = gmvin The maximum load resistance is determined by: RL(max) = vo(max)/iL R1 + vin + _ iL VCIS (Transconductance Amplifier) VCIS Voltage to Current Converter Example iL i1 vin + R1 Load Given: vin = 2 V, R1 = 2 k vo(max) = 10 V _ + _ Find: iL , gm and RL(max) Solution: iL = i1 = vin/R1 = 2 / 2000 = 1 mA mA Note: Note: • If RL > RL(max) the op amp will saturate will • The output current, iL is independent of the load resistance. resistance. gm = io/vin = 1/R1 = 1 / 2000 = 0.5 mS 0.5 RL(max) = vo(max)/iL = 10 V / 1 mA = 10 k VCIS (Transresistance Amplifier) Summary VCIS Current to Voltage Converter RF iF _ + iin + vO - General Equations: iF = iin vo = -iFRF rm = vo/iin = RF VCIS (Transresistance Amplifier) Summary VCIS Current to Voltage Converter • Transresistance Amplifiers are used for low-power Transresistance applications to produce an output voltage proportional to the input current. the • Photodiodes and Phototransistors, which are used in the Photodiodes production of solar power are commonly modeled as current sources. current • Current to Voltage Converters can be used to convert these Current current sources to more commonly used voltage sources. current VCIS (Transresistance Amplifier) VCIS Current to Voltage Converter Example RF iF Given: iin = 10 mA RF = 200 _ + iin + vO - Solution: iF = iin = 10...
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This document was uploaded on 03/31/2014.

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