Patent ID: 7402991

Claim:
A wide bandwidth differential input attenuation circuit for an active voltage measurement probe receiving a differential input signal from a device under test comprising: first and second high frequency signal paths receiving the differential input signal with each high frequency signal path having a resistive Z 0 voltage divider network with the resistive Z 0 voltage divider network having a series resistive element coupled to a shunt resistive element via a series connected transmission line and a blocking capacitor, the first and second high frequency signal paths having a high pass filter frequency response; a differential active low pass filter circuit coupled across the blocking capacitors of the first and second high frequency signal paths with the differential active low pass filter circuit receiving the differential input signal from the first and second high frequency signal paths prior to the blocking capacitors and generating a low pass filtered differential signal coupled to the first and second high frequency signal paths after the blocking capacitors with the differential active low pass filter circuit having a low pass characteristic matched to the frequency response of the respective first and second high frequency signal paths; and a differential amplifier having first and second inputs with the first input of the differential amplifier coupled to the junction of the shunt resistive element of the first resistive Z 0 voltage divider network in the first high frequency signal path and the second input of the differential amplifier coupled to the junction of the shunt resistive element of the second resistive Z 0 voltage divider network in the second high frequency path.