Signal Microwave, in partnership with DVT Solutions, is introducing a series of differential probes. The DVT-FPPXX family are 40, 50 and 70 GHz true differential probes. These probes are designed to support the industry’s demand for higher data rates over differential traces. They are used to characterize transmission lines and devices such as 28 to 56 GHz Nyquist bandwidth S-parameters for standards such as PCIe5 and for current and future PAM4 and PAM5 encoding board and system designs.
To meet these needs, a newly patented differential probe design was developed. This differential probe replaces internal cable wires with a printed circuit board (PCB) with a high bandwidth differential transmission line that can be used with test equipment to measure differential S-parameters up to 70 GHz. The probe can also be used on packages and other devices that have differential inputs and outputs and wider spacing in the 1.0 mm range. The probes have two signal probe tips and no ground probe tips, which helps to reduce setup time. The probes have only two conductors at the probe tips with a characteristic impedance of 100 Ω. The two inputs from the 50 Ω connectors are converted to a differential pair and the ground plane is removed to create the true odd mode differential configuration at the probe tips. The new differential probe satisfies the need to probe PCB designs that have wide pitch test pads up to 70 GHz with a test pad pitch centering around 1 mm. These differential probes are used to make time and frequency domain measurements of final prototype PCB products to compare against design specifications and simulation results. There are also de-embedding methods and boards available that support the probes.
Signal Microwave, LLC