An Electro-Optic Pulsed NVNA Load–Pull System for Distributed $E$ -Field Measurements

In this paper, a new combined electro-optic (EO) and pulsed nonlinear vector network analyzer-based (NVNA) load–pull measurement system for distributed multiharmonic electric field ( $E$ -field) measurements is presented. The system uses an external EO probe to measure cross-frequency phase-coherent multiharmonic vector $E$ -fields with an 8- $\mu \text{m}$ spatial resolution and 20 MHz–20 GHz bandwidth. We demonstrate the performance of the distributed phase-coherent $E$ -field measurements of $E_{x}$ , $E_{y}$ , and $E_{z}$ components with three harmonics above a commercially available large periphery, packaged, laterally diffused metal-oxide-semiconductor transistor. The transistor was measured at 2.2 GHz under pulsed conditions with 10- $\mu \text{s}$ pulse and 10% duty cycle, while outputting 55.1 dBm of power. The measured $E$ -fields of the operating transistor are animated for the first time and reveal complex nonuniform operation at harmonic frequencies.