1. SUMMING AMPLIFIER INTEGRATOR DIFFERENTIATOR COMPARATOR
OP-AMP CIRCUITS
SUMMING AMPLIFIER
INTEGRATOR
DIFFERENTIATOR
COMPARATOR

2. SUMMING AMPLIFIER May be inverting or non-inverting
More than one input
Output is the amplified sum of the input signals

3. Inverting Summer Applying KCL at the inverting terminal node, V1 VoutRF
Vout i1 i2 i3 i4
Applying KCL at the inverting terminal node,

4. Where,
The output voltage is the sum of the three input voltages, with different weighting factors.

5. If the three input resistances are equal , i.e. R1 = R2 = R3 = R

6. Non-inverting Summer V2 V1
Vout R1 R2 RF RS V+
Applying superposition theorem, i.e. apply one input at a time and determine the corresponding output, then combine the results.

7. Output due to V1 only V1 R1 R2 RF RS V+
Vout1

8. Output due to V2 only
Vout2 V2 R1 R2 RF RS V+

9. Combining the two individual results,
For n inputs and with R1 = R2 = Rn = R,

10. Vout = - [0.5 sin(1000t) + 0.33 sin(3000t)]
Example 1
Calculate the output voltage for the circuit below. The inputs are V1 = 50 mV sin(1000t) and V2 = 10 mV sin(3000t). V2 V1
Vout
10 k
33 k
330 k
Answer
Vout = - [0.5 sin(1000t) sin(3000t)]

11. Example 2 Find Vout using the superposition theorem. Answer
1 k
9 k
2 k
3 k
Answer
Vout = 6V1 + 4V2

12. Applications - DAC A binary-weighted resistor DAC +V RF 8R 20 4R 21 2R
Vout +V 21 20 22 23

13. R/2R ladder DAC 2R R RF
Vout D1 D0 D2 D3
inputs 2R

14. INTEGRATOR R C
Vin
Vout

15. Input & ouput waveform
INPUT
OUTPUT

16. A Practical Integrator
A shunt resistor added in parallel with capacitor – to prevent saturation R C
Vin
Vout RF

17. DIFFERENTIATOR R C
Vout
Vin

18. Input & output waveform

19. A Practical Differentiator
A shunt capacitor and a series resistor are added – to reduce high frequency noise RS C CF R
Vin
Vout