[CIRCUIT IDEAS]Current to Voltage Converter DEEPAK GUPTA Faiz Ashraf Most of the devices require voltage as an input quantity such as a current source, a bipolar transistor, a tube, a F
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Current to
Voltage Converter
DEEPAK GUPTA
Faiz Ashraf
Most of the devices require voltage as an input
quantity such as a current source, a bipolar
transistor, a tube, a FET transistor, etc.Only some
devices have a current input such as an ammeter, a
transimpedance amplifier, a Norton amplifier, etc
In these cases, we connect a voltage-to-current converter before the device Current to Voltage converter are commonly used in receivers for optical communications to convert the current generated by a photo detector into a voltage signal for further amplification
A simple I2V converter can be built using OP-AMP741 Operational amplifiers are widely used in signal processing circuits, control circuits, and instrumentation Of all analog integrated circuits, the operational amplifier is the analog integrated circuit which has the most sales and is the most widely used in the widest variety of electronic circuits Its input ideally has zero impedance, and the input signal is a current Its output may have low impedance, or in high-frequency applications, may
be matched to a driven transmission line; the output signal is measured as a voltage
The pin diagram of OP-AMP 741 is In the schematic diagram pin 4 & 7 are the supply pins Pin number 1 &5 the offset null pins and can be ignored Pin 2 is the inverting input and Pin 3 is the non-inverting one Pin 6 is the output The output
cannot go above +Vcc or below -Vcc When the output reaches these limits the op amp is said to be saturated The circuit diagram is A variable voltage is connected to the inverting terminal of the op-amp through a 1M-Ohm résistance The non-inverting terminal is grounded Because no current flows into the op amp itself, the current Iin has nowhere
to go but through the resistor R2 Iin=Vin/R1
Vout= -R2 X Iin
As seen, the output voltage is proportional to the input current but
of inverting nature The output voltage can be increased by increasing the feedback resistor
1
2
3
6 7
8
-input
+input
-15V
offset null
no connect
+Vcc
-+
offset null -Vcc
Fig 1 Pinout for the 741 op amp.
Current Source Current - to - Voltage Converter
R2 = 100kΩ
R1 = 1MΩ
+
3-15V
-+