Wideband active-passive differential signal probe

1. A probe for communicating a differential signal of a device under test, said differential signal comprising at least one of a higher frequency component, including at least one of a higher frequency common mode signal and a higher frequency differential mode signal, and a lower frequency component, including at least one of a lower frequency common mode signal and a lower frequency differential mode signal, said probe comprising:

(a) a choke attenuating said higher frequency common mode signal of said differential signal and having a choke output comprising at least one of said higher frequency differential mode signal and said lower frequency component of said differential signal;

(b) a first filter blocking said higher frequency differential mode signal of said choke output and transmitting said lower frequency component of said choke output;

(c) a differential amplifier attenuating said lower frequency common mode signal of said lower frequency component transmitted by said first filter and converting said lower frequency differential mode signal to a single ended, lower frequency signal;

(d) a second filter blocking transmission of said lower frequency component of said common mode choke output and transmitting a higher frequency single ended signal corresponding to said higher frequency differential mode signal; and

(e) a combiner summing said single ended, lower frequency signal and said single ended, higher frequency signal.

2. The probe of claim 1 wherein a loop gain of said differential amplifier is less than unity.

3. A probe for communicating a differential signal of a device under test, said differential signal comprising at least one of a higher frequency component, including at least one of a higher frequency common mode signal and a higher frequency differential mode signal, and a lower frequency component, including at least one of a lower frequency common mode signal and a lower frequency differential mode signal between a device under test and an instrument, said probe comprising:

(a) a choke attenuating said higher frequency common mode signal of said differential signal and having a choke output comprising at least one of said higher frequency differential mode signal and said lower frequency component of said differential signal;

(b) a first filter blocking said higher frequency differential mode signal of said choke output and transmitting said lower frequency component of said choke output;

(c) a differential amplifier attenuating said lower frequency common mode signal of said lower frequency component transmitted by said first filter and converting said lower frequency differential mode signal to a single ended, lower frequency signal;

(d) a second filter blocking transmission of said lower frequency component of said common mode choke output and transmitting a higher frequency single ended signal corresponding to said higher frequency differential mode signal; and

(e) a resistive combiner to combine said single ended, lower frequency signal and said single ended, higher frequency signal;

(f) a first attenuator conductively connected to said combiner and to an input of said differential amplifier; and

(g) a second attenuator conductively connected to said combiner and to an output of said differential amplifier.

4. A probe for communicating a differential signal of a device under test, said differential signal comprising at least one of a higher frequency component, including at least one of a higher frequency common mode signal and a higher frequency differential mode signal, and a lower frequency component, including at least one of a lower frequency common mode signal and a lower frequency differential mode signal, said probe comprising:

(a) a choke attenuating said higher frequency common mode signal of said differential signal and having a choke output comprising at least one of said higher frequency differential mode signal and said lower frequency component of said differential signal;

(b) a first filter blocking said higher frequency differential mode signal of said choke output and transmitting said lower frequency component of said choke output;

(c) a differential amplifier attenuating said lower frequency common mode signal of said lower frequency component transmitted by said first filter and converting said lower frequency differential mode signal to a single ended, lower frequency signal;

(d) a second filter blocking transmission of said lower frequency component of said common mode choke output and transmitting said higher frequency differential mode signal;

(e) a distributed amplifier receiving said higher frequency differential mode signal and outputting a single ended higher frequency signal; and

(f) a resistive combiner to combine said single ended, lower frequency signal and said single ended, higher frequency signal.

5. A probe for communicating a differential signal of a device under test, said differential signal comprising at least one of a higher frequency component, including at least one of a higher frequency common mode signal and a higher frequency differential mode signal, and a lower frequency component, including at least one of a lower frequency common mode signal and a lower frequency differential mode signal, said probe comprising:

(a) a choke attenuating said higher frequency common mode signal of said differential signal and having a choke output comprising at least one of said higher frequency differential mode signal and said lower frequency component of said differential signal;

(b) a first filter blocking said higher frequency differential mode signal of said choke output and transmitting said lower frequency component of said choke output;

(c) a differential amplifier attenuating said lower frequency common mode signal of said lower frequency component transmitted by said first filter and converting said lower frequency differential mode signal to a single ended, lower frequency signal, said differential amplifier having;

(i)a variable lower frequency common mode signal input impedance; and

(ii)a variable lower frequency differential mode signal input impedance;

(d) a second filter blocking transmission of said lower frequency component of said common mode choke output and transmitting said higher frequency differential mode signal;

(e) an attenuator of said higher frequency differential mode signal transmitted from said second filter;

(f) a distributed amplifier receiving said attenuated higher frequency differential mode signal and outputting a single ended higher frequency signal; and

(g) a combiner summing said single ended, lower frequency signal and said single ended, higher frequency signal.