LT1797 Linear Technology, LT1797 Datasheet - Page 9

• Manufacturer Part Number: LT1797
• Description: 10MHz/ Rail-to-Rail Input and Output Op Amp in SOT-23
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
Distortion
There are two main contributors to distortion in op amps:
output crossover distortion as the output transitions from
sourcing to sinking current and distortion caused by
nonlinear common mode rejection. If the op amp is
operating in the inverting mode, there is no common mode
induced distortion. If the op amp is operating in the PNP
input stage (input is not within 1.2V of V
BIAS
–IN
+IN
R5
R6
D1
U
D2
Q5
QB1
U
Q1
R1
Q6
Q2
W
R2
+
), the CMRR is
Q3 Q4
R3
Figure 1. Simplified Schematic
I1
U
R4
Q11
Q13
I2
I4
Q7
Q9
Q10
very good, typically 95dB. When the LT1797 switches
between input stages there is significant nonlinearity in the
CMRR. Lower load resistance increases the output cross-
over distortion, but has no effect on the input stage
transition distortion. For lowest distortion the LT1797
should be operated single supply, with the output always
sourcing current and with the input voltage swing between
ground and (V
Characteristic curves.
Q8
I6
1/2 SUPPLY
Q14
Q12
I5
I3
Q18
Q15
+1
+
– 1.2V). See the Typical Performance
Q16
I7
R7
Q17
R8
+1
C2
C1
CM
LT1797
Q19
Q20
1797 F01
OUT
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