Vector-receiver load pull is a modern and efficient methodology for load pull measurements. Vector-receiver load pull uses the same automated impedance tuners to tune the impedance presented to the source and/or load of the DUT. However, instead of using a scalar power meter to measure scalar powers, a vector-receiver (normally of a vector network analyzer, VNA) is used to measure the vector a- and b-waves at the DUT reference plane. This is achieved by connecting the direct receiver access of the VNA to low-loss couplers placed between the tuners and DUT and calibrating the system at the DUT reference plane. A1, b1, a2 and b2 are measured for each frequency, and from these vectors we are able to calculate available and delivered input power, output power, transducer and power gain, efficiency and true power added efficiency.
Calibration at DUT Reference Plane
Additionally, because we are calibrated at the DUT, we can measure the large signal input impedance in real-time, monitor for oscillations (gamma in>1) and measure the mismatch to calculate actual delivered power to the input of the DUT. We can also look into the tuners and measure the impedance presented to the DUT, not relying on the pre-calibrated (pre-characterized) impedances and losses. And since the measurements are made at the DUT reference, there is no mathematical de-embedding (eliminates a source of measurement error). Signals include CW or pulsed-CW, single-tone or two-tone with their respective measurement parameters (by default measured on a frequency-by-frequency basis given the a- and b-waves are frequency dependent).