A Packaged 0.01-26-GHz Single-Chip SiGe Reflectometer for Two-Port Vector Network Analyzers

This article presents a packaged SiGe BiCMOS reflectometer for 0.01–26-GHz two-port vector network analyzers (VNAs). The reflectometer chip is composed of a resistive bridge coupler and two wideband heterodyne receivers for coherent magnitude and phase detection. In addition, a high-linearity receiver channel is designed to accommodate ~20 dBm of RF input power to the reflectometer. External sources are used to provide stimulus over the entire bandwidth, and a high-linearity shunt 50- $\Omega $ switch is placed at the input of each reflectometer chip to provide a matched condition for better measurement accuracy. The measured dynamic range (DR) of the heterodyne receiver is 129±3 dB at 0.01–26 GHz at an IF resolution bandwidth (RBW) of 10 Hz. The reflectometer chip is packaged on a low-cost printed circuit board (PCB) and connectorized for repeatable measurements. Several passive and active device-under-test (DUTs), such as filters and amplifiers, are measured in single- and dual-port complex $S$ -parameter setup at 0.01–26 GHz. The single-chip reflectometer results in excellent agreement with commercially available test equipment and with minimal magnitude and phase difference. Several definitions (mean deviation and error vector) are used to quantify the measurement accuracy. A measured $S_{21}$ of −80 dB is obtained using high-rejection filters. An in-depth DR analysis of possible limiting factors in the measurement setup is also presented. This article shows that silicon-based highly integrated reflectometers can be used in low-cost VNAs with excellent DR and accuracy.