This chapter provides information and steps for using a VectorStar ME7838x System and a 3744A-Rx mmWave Receiver Module to make noise figure measurements. Most of this chapter will focus on a 2-port measurement with Option 41 and an ME7838A/D/E. The principles are the same for differential measurements with Option 48, except the same processes are applied to a second receiver path as well.
The need for direct access to the sampler (or harmonic mixer) down converters is what has prevented using VNAs in the past from performing reasonably accurate mmWave noise figure measurements. The diagram in Figure: mmWave Noise Figure Measurements illustrates why this has been a problem.
• Typical mmWave modules do not have direct access loops.
• Performing cold-source mmWave NF measurements using standard mmWave modules would not provide adequate measurement uncertainty.
• The loss introduced by the couplers (and thus increase in noise figure) results in unacceptable noise figure uncertainties.
mmWave Noise Figure Measurements
The 3744A-Rx Receiver Module
Reconfiguring the architecture of the 3743A module (as shown in Figure: VectorStar 30 GHz to 125 GHz 3744A-Rx mmWave Receiver Module) allows bypassing of the coupler and provides a direct connect to the mmWave module samplers. The result is a mmWave receiver (3744A-Rx) operating from 30 GHz to 125 GHz and with noise figure performance that now makes it possible to measure mmWave devices up to 125 GHz with more reasonable uncertainties.
VectorStar 30 GHz to 125 GHz 3744A-Rx mmWave Receiver Module
The Receiver module kit consists of:
• One 3744A-Rx Receiver Module and Mounting Bracket
• One USB drive with receiver calibration file
Characterization of the 3744A-Rx receiver is a factory characterization with appropriate files stored on the USB drive.
