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AnalyzedResult property

Class: rfckt.mixer
Package: rfckt

Computed S-parameters, noise figure, OIP3, and group delay values

Values

rfdata.data object

Description

Handle to an rfdata.data object that contains the S-parameters, noise figure, OIP3, and group delay values computed over the specified frequency range using the analyze method. The default is a 1-by-1 rfdata.data object that contains the S-parameters, noise figure, OIP3, and group delay values that result from analyzing the values stored in the default.amp file at the frequencies stored in this file.

The analyze method computes the AnalyzedResult property using the data stored in the rfckt.mixer object properties as follows:

• The analyze method uses the data stored in the 'NoiseData' property of the rfckt.mixer object to calculate the noise figure.

• The analyze method uses the data stored in the 'PhaseNoiseLevel' property of the rfckt.mixer object to calculate phase noise. The analyze method first generates additive white Gaussian noise (AWGN) and filters the noise with a digital FIR filter. It then adds the resulting noise to the angle component of the input signal.

The method computes the digital filter by:

1. Interpolating the specified phase noise amplitude to determine the phase noise values at the modeling frequencies.

2. Taking the IFFT of the resulting phase noise spectrum to get the coefficients of the FIR filter.

• The analyze method uses the data stored in the 'NonlinearData' property of the rfckt.mixer object to calculate OIP3.

If power data exists in the 'NonlinearData' property, the block extracts the AM/AM and AM/PM nonlinearities from the power data.

If the 'NonlinearData' property contains only IP3 data, the method computes and adds the nonlinearity by:

1. Using the third-order input intercept point value in dBm to compute the factor, f, that scales the input signal before the mixer object applies the nonlinearity:

${F}_{AM/AM}\left(u\right)=u-\frac{{u}^{3}}{3}$

2. Computing the scaled input signal by multiplying the mixer input signal by f.

3. Limiting the scaled input signal to a maximum value of 1.

4. Applying an AM/AM conversion to the mixer gain, according to the following cubic polynomial equation:

${F}_{AM/AM}\left(u\right)=u-\frac{{u}^{3}}{3}$

where u is the magnitude of the scaled input signal, which is a unitless normalized input voltage.

• The analyze method uses the data stored in the 'NetworkData' property of the rfckt.mixer object to calculate the group delay values of the mixer at the frequencies specified in freq, as described in the analyze reference page.

• The analyze method uses the data stored in the 'NetworkData' property of the rfckt.mixer object to calculate the S-parameter values of the mixer at the frequencies specified in freq. If the 'NetworkData' property contains network Y- or Z-parameters, the analyze method first converts the parameters to S-parameters. Using the interpolation method you specify with the 'IntpType' property, the analyze method interpolates the S-parameter values to determine their values at the specified frequencies.

Specifically, the analyze method orders the S-parameters according to the ascending order of their frequencies, fn. It then interpolates the S-parameters, using the MATLAB® interp1 function. For example, the curve in the following diagram illustrates the result of interpolating the S11 parameters at five different frequencies.

For more information, see "One-Dimensional Interpolation" and the interp1 reference page in the MATLAB documentation.

As shown in the preceding diagram, the analyze method uses the parameter values at fmin, the minimum input frequency, for all frequencies smaller than fmin. It uses the parameters values at fmax, the maximum input frequency, for all frequencies greater than fmax. In both cases, the results may not be accurate, so you need to specify network parameter values over a range of frequencies that is wide enough to account for the mixer behavior.

RF Toolbox™ software computes the reflected wave at the mixer input (b1) and at the mixer output (b2) from the interpolated S-parameters as

$\left[\begin{array}{c}{b}_{1}\left({f}_{in}\right)\\ {b}_{2}\left({f}_{out}\right)\end{array}\right]=\left[\begin{array}{cc}{S}_{11}& {S}_{12}\\ {S}_{21}& {S}_{22}\end{array}\right]\left[\begin{array}{c}{a}_{1}\left({f}_{in}\right)\\ {a}_{2}\left({f}_{out}\right)\end{array}\right]$

where

• fin and fout are the mixer input and output frequencies, respectively.

• a1 and a2 are the incident waves at the mixer input and output, respectively.

The interpolated S21 parameter values describe the conversion gain as a function of frequency, referred to the mixer input frequency.

Examples

```mix1 = rfckt.mixer;
mix1.AnalyzedResult

ans =

Name: 'Data object'
Freq: [191x1 double]
S_Parameters: [2x2x191 double]
GroupDelay: [191x1 double]
NF: [191x1 double]
OIP3: [191x1 double]
Z0: 50
ZS: 50
ZL: 50
IntpType: 'Linear'```