Measurement Guidelines

• IMD Tests - more Receive Attn is better
• Noise Figure - Use 0 dB Rec Attn.
• Set DB Current Limit = DB I Meas Max.
• Set VI Current Limit > VI I Meas Max.
• RF Sources - Levels <-22 to >+13 dBm
• DMSG - Optimum levels <-5 dBm
• RF Off is <-30 dBm

• Receive Attenuation
• IF Gain
• Signal Dependent
• Single tone
• Multi tone
• Measurement Repeatability

• Receive Attenuator
• Mixer
• IF Filter
• IF Amplifier
• Receiver Detector

• System Receiver Mixer
• Saturate
• Generate Intermodulation Distortion

• Receiver Detector
• Compression
• "Fold Over"

• RF Power, S-Parameter, Noise Figure
• Objectives
• Maximize Power to Receiver
• Maximize Power to Mixer
• Set Appropriate IF Gain

• Set IF Gain to 20dB or lower
• Reduce Rx Atten Until Warning Message
• Backoff One Rx Atten Setting
• Increase IF Gain Until Warning Message
• Backoff One IF Gain Setting

• IM3/5/7 and ACPR
• Measure Device not Tester's Mixer
• Operate in the Mixer's Linear Range
• The Mixer Can Add to or Subtract from
• the Measurement

• Receive Attenuator Controls Mixer IM
• Performance and System Noise Floor

Muilti Tone Method

• Measuring Main Tone(s)
• Not Sensitive to Mixer IMs
• Use Method for Single Tone
• Measuring IM & ACPR Tones
• Sensitive to Mixer's IM performance
• IF Gain usually at or near Maximum (Minimize noise floor)
• Verify with Spectrum Analyzer (SA)
• Be careful of SA's intermods!

• Set IF Gain 50/55; Receive Atten 20 dB
• Measure C/I
• Verify with Spectrum Analyzer
• Go to break point
• Set Receive input to Aux out
• Measure C/I
• If Different, Increase RF Attenuator
• Repeat

• Verify High and Low IM Tones
• Use Highest Linear Power DUT Condition
• Typically 20 dB Rx Atten, 55 dB IF Gain
• Too Much Rx Atten Raises Noise Floor