# 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