Patent ID: 7855544

Claim:
A probe system for connecting a measurement apparatus to a DUT, said system comprising: an AC probe having an AC shield conductor and an AC probe conductor shielded by said AC shield conductor; a first DC probe having a first DC probe conductor and a first guard conductor for guarding said first DC probe conductor when a virtual version of a voltage on said first DC probe conductor is applied to said first guard conductor; a second DC probe having a second DC probe conductor and a second guard conductor for guarding said second DC probe conductor when a virtual version of a voltage on said second DC probe conductor is applied to said second guard conductor; a first capacitive connection between said AC shield conductor and said first guard conductor; a second capacitive connection between said AC shield conductor and said second guard conductor; a third capacitive connection between said first guard conductor and said first DC probe conductor; and a fourth capacitive connection between said second guard conductor and said second DC probe conductor, each DC probe guard conductor having a virtual version of a DC voltage present on the respective DC probe conductor for DC measurements on the DUT by the measurement apparatus and said DC probe conductors providing an AC ground conductor for AC measurements on the DUT by the measurement apparatus.