Chapter 9:DC Performance :Bias,Offsets and Drift

Exampme 9.1 Page No. 256

In [1]:
#Given
Ibplus=0.4       #MicroA
Ibminus=0.3       #MicroA

#calculation
Ib=(Ibplus+Ibminus)/2.0
Ios=Ibplus-Ibminus

#Result
print"The average bias current is",Ib,"microA"
print"The offset current is",Ios,"microA"

The average bias current is 0.35 microA
The offset current is 0.1 microA

Exampme 9.2 Page No. 257

In [8]:
#Given
Vo=0.4            #A
Rf=1*10**6       #ohm

#Calculation
Ibminus=Vo/Rf

#Result
print"The Ibminus is",Ibminus*10**6,"microA"

The Ibminus is 0.4 microA

Exampme 9.3 Page No.258

In [1]:
#Given
Vo=-0.3            #A
Rf=1*10**6       #ohm

#Calculation
Ibplus=-Vo/Rf


#Result
print"The Ibplus is",Ibplus*10**6,"microA"

The Ibplus is 0.3 microA

Exampme 9.4 Page No. 260

In [15]:
#Given
Rf=100.0      #kohm
Ri1=10.0       #kohm
Ri2=100.0      #kohm

#Calculation
R1=Rf*Ri1/(Rf+Ri1)
R2=Rf*Ri2/(Rf+Ri2)

#Result
print"(a) The value of resistance is",round(R1,1),"ohm"
print"(b) The value of resistance is",R2,"ohm"

(a) The value of resistance is 9.1 ohm
(b) The value of resistance is 50.0 ohm

Exampme 9.5 Page No. 262

In [16]:
#Given
Vio=1      #mV
Rf=1       #kohm
Ri=10      #ohm

#calculation
Vo=(Vio+(Rf*1000/Ri)*Vio)

#result
print"The value of Vo is",Vo,"mV"

The value of Vo is 101 mV

Exampme 9.6 Page No. 268

In [24]:
#Given
T1=75.0           #Temprature ,C
T2=25.0           #Temprature ,C
Viomax=20.0       #microV, Voltage
Ioschange=0.1   #nm
Rf=10**6       #ohm
Ri=10*10**3    #ohm

#Calculation
Vio=Viomax*(T1-T2)
change=Vio*(1+Rf/Ri)
Ioschange=Ioschange*(T1-T2)
Vochange=Ioschange*Rf

#Result
print"The change in Vo due to change in Vio is",change/10**3,"mV"
print"The change in Vo due to change in Ios is",Vochange/10**6,"mV"

The change in Vo due to change in Vio is 101.0 mV
The change in Vo due to change in Ios is 5.0 mV

Exampme 9.7 Page No. 270

In [40]:
#given
Vo=0.421     #V,
Vo1=0.097
Vo2=-0.082
Rf1=5000     #from fig 9-10(a)
Ri=50
Rf2=1.0        #Mohm fig 9-10 (b)

#calculation
Vio=Vo/(1+Rf1/Ri)
Ibminus=(Vo1*1000-Vio*1000)/Rf2
Ibplus=-(Vo2*1000-0.0041*1000)/Rf2

#Result
print"The value of Vio is",round(Vio*1000,1),"mV"
print"Ibminus is",round(Ibminus,0),"nA"
print"Ibplus is",round(Ibplus,0),"nA"
print"Ios calculated as",round(Ibplus-Ibminus,0),"nA"

The value of Vio is 4.2 mV
Ibminus is 93.0 nA
Ibplus is 86.0 nA
Ios calculated as -7.0 nA