Concept explainers
(a)
Interpretation:
Current follower that will produce a 1.0 V output for 10.0 µA input current should be designed.
Concept introduction:
Operational amplifiers can be used to measure or process currents by connecting them in the current follower mode. This mode provides a nearly zero resistance load to the current source and prevents it from being loaded by a measuring device or circuit.
Here,
V+, V- = input voltages
Vs = Input difference voltage
V0 = output voltage
ib = input bias current
if = feedback current
ii = input current
Rf = feedback resistor
Also,
(b)
Interpretation:
Effective input resistance of the current follower designed in part (a) should be calculated.
Concept introduction:
Here,
V+, V- = input voltages
Vs = Input difference voltage
V0 = output voltage
ib = input bias current
if = feedback current
ii = input current
Rf = feedback resistor
Ri = effective input resistance
A = open loop gain
Also,
(c)
Interpretation:
The percent relative error for the circuit designed in part (a) for an input current of 25 µA should be calculated.
Concept introduction:
Here,
V+, V- = input voltages
Vs = Input difference voltage
V0 = output voltage
ib = input bias current
if = feedback current
ii = input current
Rf = feedback resistor
Ri = effective input resistance
A = open loop gain
Here,
Also,
Thus,
Relative error percentage =
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