Abstract: An integrated circuit device having improved substrate capacitance isolation for use in a ultra low capacitance probe or an input to an oscilloscope or the like has an electrically conductive layer formed directly underneath an input node on the integrated circuit. The electrically conductive layer has a geometry substantially equal to the input node and is driven by a voltage output from a high impedance unity gain circuit. In one embodiment, the electrically conductive layer is formed in the first metal layer of the integrated circuit while an alternate embodiment an emitter region of a semiconductor device in the high impedance circuit is used as the electrically conductive layer.

Abstract: An improved variable voltage transition circuit of the type that switches a capacitor between charging and discharging current sources when an input voltage transitions, the capacitor being coupled via respective Schottky diodes to tracking clamp circuits, has a compensation circuit that includes second current sources that match the charging and discharging current sources and uses regenerative feedback to turn on and off the Schottky diodes virtually instantaneously when the input voltage transitions. A fixed clamp circuit and a bias switch circuit are coupled between the tracking clamp circuits and one side of the transition switch to provide a conductive path for the second current sources that results in a change in the bias of the tracking clamp circuits such that when the input voltage transitions the "on" Schottky diode is instantaneously turned off, and the "off" Schottky diode is turned completely on very quickly after it starts to conduct at the end of the transition.

Abstract: An active electrical test probe with wideband frequency capability for use on a test probe card, along with other test probes. A small hybrid integrated circuit is mounted on a substrate held on edge, adjacent the probe tip contact element of the probe, by a conductive metal clip. The circuit is provided power from an external source. Signals received by the probe tip are transmitted, as modified by the hybrid integrated circuit, through an output cable to electronic test equipment.

Abstract: A probe for use in electrical circuit test equipment, in which a contact element is longitudinally slidable in an insulator sleeve which also contains an R-C attenuator circuit connected electrically to the contact element by an electrically conductive elastomeric material. A high impedance cable is connected electrically to the other end of the RC attenuator circuit by another piece of conductive elastomeric material. The cable connects the attenuator to another R-C circuit which, together with the attenuator, forms a voltage divider, and the attenuated signal controls an amplifier which provides a signal through a low impedance cable to a test equipment.