Patent ID: 6753690
Filing Date: 2004-06-22
Classification: G01R

Abstract:
An interferometric signal processing apparatus for producing an output signal indicative of a characteristic of a device-under-test from a first input signal, a second input signal and a carrier-dominated input signal having substantially equal carrier frequencies, said interferometric signal processing apparatus comprising:a bridge having a first arm and a second arm, each of said first and second arms including first ends and second ends, said first and second arms receiving the first and second input signals at said first ends, respectively, the device-under-test being connected to said first arm between said first and second ends thereof: a carrier suppressor connected to said second ends of said first arm and said second arm, in conjunction with said second arm, and having an output for transmitting a carrier-suppressed signal, said carrier-suppressed signal including the characteristic of the device-under-test; an amplifier electrically connected to said output of said carrier suppressor for amplifying said carrier-suppressed signal to produce an amplified carrier-suppressed signal; a mixer having a first mixer input for receiving said amplified carrier-suppressed signal and a second mixer input for receiving said carrier-dominated input signal to produce the output signal indicative of the characteristic of the device-under-test at an output thereof; and a delay provided in one of said first arm and said second arm to minimize a differential group delay between said first and second arms to a value not greater than 1000/fo seconds, wherein fo is a time-averaged mean value of the carrier frequencies of the first input signal and second input signal, measured in Hertz.