TS612

6/11

INTERMODULATION DISTORTION

The curves shown below are the measurements results of a single operator wired as an adder with a gain

of 15dB.

The operational amplifier is supplied by a symmetric

±6V and is loaded with 25Ω.

Two synthesizers (Rhode & Schwartz SME) generate two frequencies (tones) (70 & 80kHz or 180 &

280kHz).

An HP3585 spectrum analyzer measures the spurious level at different frequencies.

The curves are traced for different output levels (the value in the X ax is the value of each tone).

The output levels of the two tones are the same.

The generators and spectrum analyzer are phase locked to enhance measurement precision.

3rd ORDER INTERMODULATION

(2 tones : 70kHz and 80kHz)

2nd ORDER INTERMODULATION

Spurious measurement @ 100kHz

(2 tones : 180kHz and 280kHz)

3rd ORDER INTERMODULATION

(2 tones : 180kHz and 280kHz)

1

1,5

2

2,5

33,5

44,5

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Vout peak (V)

230kHz

220kHz

90kHz

60kHz

Vout peak (V)

1,522,5

33,5

44,5

-70

-65

-60

-55

1

1,522,533,5

4

4,5

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Vout peak (V)

80kHz

640kHz

380kHz

740kHz