In this article, we present a comprehensive analysis of the hardware and software solutions required to enable frequency scalable load-pull test benches operating in the (sub)mm-wave frequency bands. First, the constraints arising from the harmonic (nonlinear) operation of mm-wave extender modules are discussed and analyzed. Then, different hardware solutions for signal generation and control, together with the specific software algorithms required to realize a frequency scalable load-pull test bench, are presented. The measurement setup key performances are analyzed in different frequency bands up to 500 GHz, i.e., waveguide bands from WR10 up to WR2.2. Finally, the load-pull measurements on an HBT device at 75 GHz and a two-stage differential PA at 135 GHz are presented to show the capability of the proposed test bench to characterize and optimize mm-wave nonlinear components.

In this contribution, we present the performances of an IQ mixer-based RF-interferometer module, called the HΓ-VNA, designed to be used as an add-on to VNAs to improve the measurement sensitivity and accuracy of DUTs presenting extreme impedances (|Γ|>0.8). The calibration procedure used to obtain accuracy improvement is presented, and allows to set both reference and system impedance to any selected one. The procedure is benchmarked by comparing it to a conventional 50 Ω short-open-load calibration performed on a 50-Ohm VNA. For this purpose, a custom on-wafer calibration kit has been realized, using a fused silica substrate, featuring calibration loads with very high impedances (between 3.5 kΩ and 7 kΩ). Experimental results show accuracy improvements when applying the proposed calibration technique to the measurement of high impedance resistors, for frequencies below 4 GHz.

This paper analyzes and accurately models the complex noise behavior of vector network analyzers (VNAs) when measuring large-mismatch devices and subsequently shows how the VNA measurement noise performance is enhanced through implementation of a high-speed, broadband, active RF interferometer module. The presented VNA noise model provides a solid framework, benchmarked by measurement data, to analyze existing RF interferometer approaches. The performance improvement of the proposed interferometer implementation is then benchmarked in terms of magnitude and phase stability of the renormalized impedance level. A test bench employing the novel add-on RF interferometer module is presented and demonstrated to achieve high-speed cancellation of the scattered wave over a broad frequency band. The first experiment shows ultralow noise in a 1-18 GHz broadband measurement of co-planar waveguide 0.5-Ω and 5-k Ω impedance standards. Employing the proposed hardware setup improves the noise uncertainty for the 5-k Ω impedance standard by a factor of 8 and 20 at 1 and 18 GHz, respectively. In the second experiment, a factor of 2 height-resolution enhancement is achieved in a scanning microwave microscope when the RF interferometer module is added to the instrument.

In this paper we present the measurement procedure to achieve direct on-wafer absolute power calibration in VNA-based mm-wave setups. The proposed approach employs 28 nm CMOS n-channel MOSFET as the power calibration transfer device, providing sufficient responsivity up to 325 GHz. The square law conversion from mm-wave (power) to DC (voltage) through the CMOS device is employed to achieve a direct on-wafer power calibration. The use of the calibration transfer device allows for a (power) calibration procedure of a mm-wave measurement setup with zero extender movements, thus minimizing errors originating from cable movements, and reducing calibration time when compared to the standard, calorimeter based, procedure. The approach is experimentally benchmarked against the instrumentation power meters procedure in the WR5 band (140220 GHz), showing a maximum error propagated through the calibration equations, over the entire band and multiple devices, lower than 1 dB.

In this contribution we analyze the impact of radiation losses due to multimode propagations in (single medium) calibration substrates. The impact of the complex modelling of the loss mechanism due to radiation mode is applied to the specific case of TRL on-wafer calibrations for mm-wave operation. A quantitative analysis based on 3D EM simulation is performed to provide guidelines on the material to be used as the calibration substrate, the backside conditions, and the accuracy that can then be expected. Finally experimental data providing qualitative indication of the quality of calibrations on different media are presented for the WR10 band.

In this paper, we propose a method based on 3-D electromagnetic simulations, for the characteristic impedance extraction of transmission lines employed in TRL calibration, focusing on lines integrated in silicon technologies. The accuracy achieved with TRL calibrations using the proposed characteristic impedance extraction is benchmarked versus conventional approaches, with an emphasis on aluminum pads structures operating in the (sub) millimeter-wave range. The proposed method proves to be insensitive to common sources of error (i.e., large pad capacitance and inductive pad-to-line transitions), which affect the accuracy of characteristic impedance extraction based on measurements, especially as the testing frequency increases. First, direct on-wafer TRL calibrations are performed on uniform CPWs (i.e., with no pads discontinuities) to demonstrate how the proposed method performs as good as the calibration comparison method and outperforms calibration transfer approaches. Finally, the method is applied to a nonuniform CPW-based calibration kit, demonstrating how the proposed method provides accurate results, improving the calibration quality that can be achieved using the calibration comparison method when inductive pad-to-line transitions are present.