State of the art microwave power amplifier measurements use a measurement in a fixed operating point with a fixed signal. As these amplifiers are operated in more and more diverse and variable environments, the need for a characterisation of the devices over a wider range of complex operating conditions grows too. To tackle the challenges imposed by the massive MIMO communication, characterisation will be required over a wide frequency band, a wide range of powers, and a wide range of linear and nonlinear loading impedances. Current instrumentation falls short to meet these challenges.
We want to measure the linearized and nonlinear behaviour of the PA over a range of powers, a broad frequency band and a variable loading impedance in a single experiment. To this end, we first design a non-stationary signal that covers the space. Next, we use transient and time-variation detection and estimation techniques to impose a user-specified accuracy level. To tackle the complex non-linear loading of the PA’s that are connected to a MIMO antenna panel, we use a second amplifier that is driven in nonlinear regime and is used as an active, nonlinear load for the device under test.
To tackle this engineering challenge, you will
- design the non-stationary signals off-line, perform a measurement and then assess the level of transient and time-varying behaviour present in the response.
- Link the measured non-ideal behaviour to the accuracy of the measurement, and adapt the designed signal if needed
- extract the nonlinear behaviour of the PA and its dependence op power level, and output impedance presented by the load
- use active load-pull with a second amplifier that is driven in nonlinear regime to create a nonlinear loading impedance for the PA
- use the model with the nonlinear loading to predict the influence of the nonlinear crosstalk on a MIMO antenna driven by the PA