The Noise Figure Uncertainty Calculator

This calculator is designed to determine the uncertainty of two-port devices like amplifiers or of frequency converting devices like mixers and receivers.

Instructions - Overview

The Uncertainty Calculator can be used for either of the following cases:

1. Modelling the performance of your system. For this purpose, defaults are available for Agilent's noise figure instruments and noise sources. These defaults have typical¹ values associated with them and can be useful for estimating the effect individual parameters have in overall uncertainty levels. However, actual equipment may have different values to those shown as the default typical value. If you already own the equipment that you are modelling, please refer to the calibration certificate for the measured instrument uncertainties. With these actual values, the results you obtain will have higher accuracy for your particular set up. For this operation please select "User Defined" from the pull down selection menu.
(¹ typical values were calculated using a wide range of noise source calibration results)

2. Making actual calculations of the uncertainty of your system. For this you will need to obtain accurate values of all the associated parameters in question such as match and gain. As mentioned above, for highest accuracy or for frequency selective measurements, please consult the calibration certificates of your instruments to obtain the measured uncertainty parameters of the equipment being used.

Noise Source Selection

For the highest accuracy, and therefore most meaningful results, the 'User Defined' option from the pull down menu should be selected whenever the actual value of the noise source calibration data is available. This allows the entry of the actual uncertainty of the Excess Noise Ratio (ENR) and the 50Ω match (in dB, VSWR or reflection coefficient), which can be for the noise source of any manufacturer. Additionally, there are default values providing typical parameters for standard Agilent Technologies noise sources.

Device Parameters

The noise figure and gain values are the values that are read from the display on the measurement instrument after a calibrated measurement is made. The DUT input and output match can be obtained from the datasheet for the device or by measurement using a network analyzer.

Noise Figure Instrument Selection

For results with the highest accuracy, as with the noise source selection, the 'User Defined' option from the pull down menu should be selected whenever the actual values for the noise figure analyzer/meter are available. This allows the entry of the actual uncertainty of the instrument noise figure and gain. The values of instrument noise figure and match should be obtained from calibration reports; otherwise typical instrument default values are available. If values for the NFA instrument noise figure and match versus frequency are required, typical values can be found on the data sheet (5980-0164E - page 3 to 5) available in the "Download" section of the Noise Figure Uncertainty Overview page.

The user-defined option can also be used for the noise source of any manufacturer. Additionally, there are default values providing typical parameters for standard Agilent Technologies noise figure analyzers/meters

Sweep

This function allows an input parameter to be selected then sweep between two different values so that the variation in uncertainty can be seen. The number of points in the sweep can also be selected here.

Getting Results

Once all the parameters have been entered the results can be viewed by selecting the 'Tabular Results' button for single points or the 'Graphical Results' button for swept results. These buttons are at the top of the display along with the 'Calculator' button.