Electronics - Analog and Digital Converters - Discussion
Discussion Forum : Analog and Digital Converters - General Questions (Q.No. 8)
8.
A binary-weighted digital-to-analog converter has a feedback resistor, Rf, of 12 k
. If 50 
A of current is through the resistor, the voltage out of the circuit is:
. If 50 A of current is through the resistor, the voltage out of the circuit is:Discussion:
10 comments Page 1 of 1.
SUMAN CHOWDHURY said:
1 decade ago
Why -sign comes here?
Vijay said:
1 decade ago
Input bias current Ib is -ve
Niyas tm said:
1 decade ago
Friends, In binary weighted DAC we are using an inverting op amp. There for output will be inverted form of input. That is why we are getting -ve here.
Spm said:
1 decade ago
Output_voltage=-(Rf/R)input_voltage
R=IV
R=50microamp*V where V is assumed input_Voltage
So output_voltage=-(Rf/(50 microamp*V))*V
Output_voltage=-12k/50u
=-0.6V
R=IV
R=50microamp*V where V is assumed input_Voltage
So output_voltage=-(Rf/(50 microamp*V))*V
Output_voltage=-12k/50u
=-0.6V
GOPAL said:
1 decade ago
Thats right since inverting opamp is used output voltage is negative.
Vijay please don't get confuse with bias current :-P bias current direction doesn't matter here as input and output of opamp are isolated:-) and if it was supposed to be negative than they would have specified in question.
Vijay please don't get confuse with bias current :-P bias current direction doesn't matter here as input and output of opamp are isolated:-) and if it was supposed to be negative than they would have specified in question.
Praveena kokrady said:
9 years ago
Use the ohms law.
I = V/R -----> (1).
Rearrange Eq- (1).
V = I * R.
I = V/R -----> (1).
Rearrange Eq- (1).
V = I * R.
Poorvi said:
9 years ago
@Praveena,
Will you please substitute the values and show it once?
Will you please substitute the values and show it once?
Dharma Mohan said:
8 years ago
V = I * R.
V = 50^-6 * 12000,
V = -6.
V = 50^-6 * 12000,
V = -6.
(2)
VIJAY said:
8 years ago
V=I*R.
V=(50 * 10^-6) * (12 * 10^3),
V=600 * 10^-3 =>0.6 V,
V= -0.6 V (-ve sign indicates the Negative feedback resistor).
V=(50 * 10^-6) * (12 * 10^3),
V=600 * 10^-3 =>0.6 V,
V= -0.6 V (-ve sign indicates the Negative feedback resistor).
Santosh yadav said:
3 months ago
In a typical binary-weighted DAC (or any inverting amplifier configuration) , the output voltage is the negative of the current multiplied by the feedback resistor.
This is because the operational amplifier (op-amp) inverts the signal.
This is because the operational amplifier (op-amp) inverts the signal.
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