Abstract: A method and apparatus compensates for phase noise added by a spectrum analyzer from phase noise measurements of a signal under test (SUT) taken by the spectrum analyzer. The method comprises the steps of measuring the phase noise of the SUT, determining the added phase noise of the spectrum analyzer, and applying a mathematical correction to the measured phase noise. A spectrum analyzer apparatus that compensates for added phase noise comprises a controller portion, a memory portion, a signal conversion and detection portion, and a compensation algorithm stored in the memory portion. A system that compensates for added phase noise comprises a controller having a control algorithm and a spectrum analyzer. The compensation and control algorithms are computer programs that implement the method of the present invention.

Abstract: A frequency synthesizer that includes an output oscillator, a difference circuit, a reference circuit, a feedback circuit and a comparator. The output oscillator generates an output signal whose frequency, FOUT, is determined by an oscillator input signal. The difference circuit generates a sampled signal having a frequency, Fsif=FOUT−FOFFSET. The reference circuit generates a reference signal having a frequency Fref. The reference circuit includes a reference oscillator for generating a high frequency reference oscillator output signal having a frequency F1 and a first division circuit for generating a signal having a frequency equal to F1 divided by R. The feedback circuit generates a feedback signal having a frequency, Ffb. The feedback signal generating circuit includes a second division circuit having a division factor chosen such that Fsif/Ffb is minimized. The comparator compares the reference signal and the feedback signal and generates the oscillator input signal.

Abstract: A phase noise measurement module (PNMM), system and method for measuring phase noise improve accuracy of phase noise measurements of a signal under test (SUT) using a spectrum analyzer. The PNMM includes an RF to hF frequency converter and a selectable frequency divider. The system includes the PNMM connected to the spectrum analyzer and employs an LO signal from a tunable LO in the spectrum analyzer. The method includes directly converting an input SUT to an IF signal having either a second or a third IF frequency that is applied to a corresponding frequency conversion stage of the spectrum analyzer before the phase noise is measured. The present invention bypasses a first conversion stage, and typically a second conversion stage as well, of the spectrum analyzer and directly converts the SUT to either the second or third IF frequency, thereby reducing phase noise added to the SUT.

Abstract: A phase noise measurement module (PNMM), system and method for measuring phase noise improve accuracy of phase noise measurements of a signal under test (SUT) using a spectrum analyzer. The PNMM comprises an RF to IF frequency converter and a selectable frequency divider. The system comprises the PNMM connected to the spectrum analyzer and employs an LO signal from a tunable LO in the spectrum analyzer. The method comprises directly converting an input SUT to an IF signal having either a second or a third IF frequency that is applied to a corresponding frequency conversion stage of the spectrum analyzer before the phase noise is measured. The present invention bypasses a first conversion stage, and typically a second conversion stage as well, of the spectrum analyzer and directly converts the SUT to either the second or third IF frequency, thereby reducing phase noise added to the SUT.

Abstract: A method and apparatus compensates for phase noise added by a spectrum analyzer from phase noise measurements of a signal under test (SUT) taken by the spectrum analyzer. The method comprises the steps of measuring the phase noise of the SUT, determining the added phase noise of the spectrum analyzer, and applying a mathematical correction to the measured phase noise. A spectrum analyzer apparatus that compensates for added phase noise comprises a controller portion, a memory portion, a signal conversion and detection portion, and a compensation algorithm stored in the memory portion. A system that compensates for added phase noise comprises a controller having a control algorithm and a spectrum analyzer. The compensation and control algorithms are computer programs that implement the method of the present invention.

Abstract: A frequency synthesizer that includes an output oscillator, a difference circuit, a reference circuit, a feedback circuit and a comparator. The output oscillator generates an output signal whose frequency, FOUT, is determined by an oscillator input signal. The difference circuit generates a sampled signal having a frequency, Fsif=FOUT−FOFFSET. The reference circuit generates a reference signal having a frequency Fref. The reference circuit includes a reference oscillator for generating a high frequency reference oscillator output signal having a frequency F1 and a first division circuit for generating a signal having a frequency equal to F1 divided by R. The feedback circuit generates a feedback signal having a frequency, Ffb. The feedback signal generating circuit includes a second division circuit having a division factor chosen such that Fsif/Ffb is minimized. The comparator compares the reference signal and the feedback signal and generates the oscillator input signal.