Third Order Intermodulation Distortion Performance Test

This test measures the Third-Order Intermodulation Distortion produced by two discrete signals, and computes the Third Order Intercept (TOI) point.

Two signals separated by 100 kHz are combined in a directional bridge or directional coupler (for isolation) and are injected into the EMI receiver input. The EMI receiver measures the amplitude of the lower and upper distortion products. TOI is computed using the higher (worst case) of these two products.

Below 3.6 GHz low-pass filters are used to attenuate the source second harmonic. The harmonic is filtered so it does not create a false failure. Above 3.6 GHz the internal YTF filters the source harmonic.

The filtered source is turned on and the signal level is measured at the splitter output port with a power meter. The filtered source amplitude is measured on the DUT. The unfiltered source is turned on and its amplitude is measured on the DUT using the DUT's delta-marker feature. The amplitude of the distortion product is then measured relative to the unfiltered source amplitude.

Click here for troubleshooting.

Required Test Equipment

Test Equipment

Model Number1

Microwave Signal Generator #1 and
Microwave Signal Generator #2

PSG Models
(see equipment list)

Power Meter

N1914A

RF Power Sensor

E9304A Option H18

Microwave Power Splitter

11667B

Millimeter Power Sensor

  • For Option 544

N8487A CFT

Millimeter Power Splitter

  • For Option 544

11667C

Directional Bridge

86205A 

Directional Coupler

87300B 

Millimeter Directional Coupler

  • For Option 544

87301C

10 dB Fixed Attenuator

8493C Option 010

10 dB Fixed Attenuator

  • For Option 544

8490D Option 010

Cable, BNC

  • 2 required

8120-1840 

Cable, coaxial, 3.5 mm

  • 3 required

11500E

Cable, coaxial, 2.4 mm

  • For Option 544
  • 2 required

8120-6164

Low pass filter, 50 MHz

Telonic Berkeley TLA 50-5AB2

Low pass filter, 1.8 GHz

  • 2 required

RLC L-1636

Adapter, 3.5 mm (f) to 3.5 mm (f)

  • 2 required
  • For 3.5 mm sources

83059B 

Adapter, BNC (m) to SMA (f)

1250-1700

Adapter, Type-N (f) to 3.5 mm (m)

1250-1750

Adapter, Type-N (m) to BNC (f)

1250-1476

Adapter, Type-N (m) to 3.5 mm (m)

1250-1743

Adapter, Type-N (m) to 3.5 mm (f)

  • 3 required

1250-1744

Adapter, 3.5 mm (m) to 3.5 mm (m)

83059A

Adapter, 2.4 mm (f) to 3.5 mm (f)

  • 2 required
  • For 2.4 mm sources

11901B 

Adapter, 3.5 mm (m) to 2.4 mm (f)

  • For Option 544

11901D

Adapter, 2.4 mm (m) to 2.4 mm (m)

  • For Option 544

11900A

Adapter, 2.4 mm (f) to Type-N (m)

  • 8487A adapter

08487-60001
  1. Refer to the main Required Equipment table for a list of alternative models.

Connection Setups

Power Meter Calibration (Channel A)

 

Power Meter Calibration (Channel B)
(for Option 544)

TOI Test Setup – RF Preselector Path

 

Third Order Intercept Distortion Low Band Test Setup

(50 MHz Low Pass Filter)

 

Third Order Intercept Distortion Low Band Test Setup

(1.8 GHz Low Pass Filter)

 

Third Order Intercept Distortion High Band Test Setup < 25 GHz

 

Third Order Intercept Distortion High Band Test Setup > 25 GHz