Availability of IP / decimal output conversion circuit

Published:2011/7/8 3:21:00 Author:Fiona | Keyword: IP / decimal output | From:SeekIC

Circuit Work As we all know,there exists logarithmic relationship between the transistor base very- occurs very voltage VBM and the collector current IO. Using this relationship can be made the log conversion circuit, the circuit principle expressed by the following relationship: IO1 and IO2 ratio is converted to logarithms, partial pressure ratio determines the constants,in order to make the change 10 times to obtain 1V output, according to [(R5 + R4) / R6] * 60 = 1000MV,it can get partial pressure ratio, the ratio value is 16.7. If R6 = 1K, then R4 = 15.7K, It adds ★ mark where the resistance is 1K at the circuit diagram, which means that in order to do the temperature compensation for transistor VBE, the resistance is thermistor which has a +3300 PPM / ℃ temperature characteristic. IC1 is the input current used for converting, reference current IC2 is supplied by the OP amplifier A2.



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