Magnitude and phase response calibration of receivers

An integrated calibrator for a wide-band radio-frequency receiver having an input for receiving a radio-frequency signal, means for converting the input radio-frequency signal to an intermediate frequency signal, a digitizer for converting the intermediate frequency signal to digital samples, a correction filter for filtering the digital samples and a receiver processor for converting the filtered digital samples to useful results, the integrated calibrator comprising:

• a two-tone source for generating a pair of sinusoidal signals separated by a specified delta frequency about a center frequency, the two-tone source being able to step the center frequency across a frequency range corresponding to the wide-band radio-frequency receiver;
• a calibrated diode operating as a square law detector, the calibrated diode having an input and an output;
• a splitter coupled to receive the pair of sinusoidal signals from the two-tone source and providing two sets of the pair of sinusoidal signals at respective outputs of the splitter, the sets having equal amplitudes and being in phase, one output of the splitter being coupled to the input of the radio-frequency receiver and the other output of the splitter being coupled to the input of the calibrated diode;
• means for processing the output from the calibrated diode for comparison with the useful results from the wide-band radio-frequency receiver processor to produce coefficients for the correction filter at each of the center frequencies;
• whereby the wide-band radio-frequency receiver has amplitude flatness and phase linearity across the frequency range.