Method and Apparatus for Estimating the Noise Introduced by a Device

摘要

An apparatus and method for measuring the properties of a DUT characterized by a signal gain applied to an input signal to that DUT and a DUT noise spectrum introduced by that DUT is disclosed. An apparatus includes first and second measurement channels and a controller. The first and second measurement channels are characterized by gains and noise spectrums that are different for the different channels and generate first and second measurement signals. The controller measures an average value of a product of the first and second measurement signals when an input signal is applied to the input of the DUT, the controller providing a measure of the signal to noise ratio of the output of the DUT, independent of the noise spectrums in the first and second measurement channels. Four channel embodiments reduce the amount of calibration needed to measure the gain and noise spectrum of the DUT.

主权项

1. An apparatus for measuring a first DUT characterized by a first DUT input, a first DUT output, a first DUT signal gain and a first DUT noise spectrum introduced by that first DUT, said apparatus comprising:
a first measurement channel that generates a first measurement signal characterized by a first gain and a first noise spectrum introduced by that channel, said first measurement channel being coupled to said first DUT output; a second measurement channel that generates a second measurement signal characterized by a second gain and a second noise spectrum introduced by that channel, said second measurement channel being coupled to said first DUT output; and a controller that measures an average value of a cross product of frequency spectrums of said first measurement signal and said second measurement signal when an input signal is said first DUT input, said controller providing a measure of a signal-to-noise ratio (SNR) of a signal leaving said first DUT output, said measure being independent of said first noise spectrum and said second noise spectrum.