Differential coaxial contact array for high-density, high-speed signals

A probe tower for an automatic test system, comprising:

• a retainer;
• and
• a plurality of differential probe assemblies held by the retainer and electrically isolated from one another, each of the plurality of differential probe assemblies including
• a conductive block, having first and second ends and a height, and first and second holes each extending through the conductive block from the first end to the second end;
• first and second center conductors respectively disposed within the first and second holes and insulated therefrom by respective insulators;
• first and second contact pins electrically connected to the center conductor and extending from the first and second ends, respectively;
• and
• first and second ground pins electrically connected to the conductive block and extending from the first and second ends, respectively.