LT1797

9

1797fc

For more information www.linear.com/LT1797

applicaTions inForMaTion

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 non-

linear common mode rejection. If the op amp is operating

in the inverting mode, there is no common mode induced

distortion.IftheopampisoperatinginthePNPinputstage

(input is not within 1.3V of V+), the CMRR is very good,

typically 96dB. When the LT1797 switches between input

stagesthereissignificantnonlinearityintheCMRR.Lower

load resistance increases the output crossover distortion,

but has no effect on the input stage transition distortion.

ForlowestdistortiontheLT1797shouldbeoperatedsingle

supply, with the output always sourcing current and with

the input voltage swing between ground and (V+ – 1.3V).

See the Typical Performance Characteristic curves.

1797 F01

Q18

Q1

Q3 Q4

QB1

Q7

Q11

Q13

Q9

Q6

Q2

Q12

Q8

Q14

Q10

Q5

Q17

Q15

Q19

Q20

Q16

R1

R3

R4

R7

R8

R5

R6

R2

D1

D2

–IN

+IN

BIAS

I1

OUT

+1

+1

CM

C1

C2

I3

I2

I4

I5

I6

I7

1/2 SUPPLY

Figure 1. Simplified Schematic