# Documentation

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# analyze

Analyze circuit object in frequency domain

## Syntax

```analyze(h,freq) analyze(h,freq,zl,zs,zo,aperture) analyze(h,freq,'condition1',value1,...,'conditionm',valuem) ```

## Description

`analyze(h,freq)` calculates the following circuit data at the specified frequency values:

• Circuit network parameters

• Noise figure

• Output third-order intercept point

• Power data

• Phase noise

• Voltage standing-wave ratio

• Power gain

• Group delay

• Reflection coefficients

• Stability data

• Transfer function

`h` is the handle of the circuit object to be analyzed. `freq` is a vector of frequencies, specified in hertz, at which to analyze the circuit. OIP3 is always infinite for passive circuits.

`analyze(h,freq,zl,zs,zo,aperture)` calculates the circuit data at the specified frequency values. The arguments `zl`, `zs`, `zo`, and `aperture` are optional. `zl`, `zs`, and `zo` represent the circuit load, circuit source, and reference impedances of the S-parameters, respectively. The default value of all these arguments is 50 ohms.

### Note

When you specify impedance values, the `analyze` method changes the object's values to match your specification.

The `aperture` argument determines the two frequency points that the `analyze` method uses to compute the group delay for each frequency in `freq`. `aperture` can be a positive scalar or a vector of the same length of as `freq`.

### Note

For `rfckt.datafile`, `rfckt.passive`, `rfckt.amplifier`, and `rfckt.mixer` objects that contain measured S-parameter data, the `analyze` method uses the two nearest measurement points to compute the group delay, regardless of the value of `aperture`.

Group delay τg at each frequency point f is the negative slope of the phase angle of S21 with respect to f:

`${\tau }_{g}\left(f\right)=-\frac{\Delta \varphi }{\Delta \omega }=-\frac{\mathrm{arg}\left({S}_{21}\left({f}_{+}\right)\right)-\mathrm{arg}\left({S}_{21}\left({f}_{-}\right)\right)}{2\pi \left({f}_{+}-{f}_{-}\right)}$`
where:

• f+ is:

• f(1 + `aperture`/2) for `aperture` < 1.

• f + `aperture`/2 for `aperture` ≥ 1.

If f is the maximum value of `freq`, then f+ = f.

• f is:

• f (1 – `aperture`/2) for `aperture` < 1.

• f – `aperture`/2 for `aperture` ≥ 1.

If f is the minimum value of `freq`, then f = f.

By default, `analyze` calculates the group delay in nanoseconds.

The value of `aperture` affects the accuracy of the computed group delay. If `aperture` is too large, the slope estimate may be not accurate. If `aperture` is too small, the computer numerical error may affect the accuracy of the group delay result.

`analyze(h,freq,'condition1',value1,...,'conditionm',valuem)` calculates the circuit data at the specified frequency values and operating conditions for the object `h`. The inputs `'condition1',value1,...,'conditionm',valuem` are the condition/value pairs at which to analyze the object. Use this syntax for `rfckt.amplifier`, `rfckt.mixer`, and `rfdata.data` objects where the condition/value pairs are operating conditions from a `.p2d` or `.s2d` file.

### Note

When you specify condition/value pairs, the `analyze` method changes the object's values to match your specification.

When you analyze a network that contains several objects, RF Toolbox™ software does not issue an error or warning if the specified conditions cannot be applied to all objects. For some networks, because there is no error or warning, you can call the `analyze` method once to apply the same set of operating conditions to any objects where operating conditions are applicable. However, you may want to analyze a network that contains one or more of the following:

• Several objects with different sets of operating conditions.

• Several objects with the same set of operating conditions that are configured differently.

To analyze such a network, you should use the `setop` method to configure the operating conditions of each individual object before analyzing the network.

### Analysis of Circuit Objects

For most circuit objects, the `AnalyzedResult` property is empty until the `analyze` method is applied to the circuit object. However, the following four circuit objects are the exception to this rule:

• `rfckt.datafile` — By default, the `AnalyzedResult` property of `rfckt.datafile` objects contains the S-parameter, noise figure, and group delay values that are calculated over the network parameter frequencies in the `passive.s2p` data file. OIP3 is ∞ by default because the data in `passive.s2p` is passive.

• `rfckt.passive` — By default, the `AnalyzedResult` property of `rfckt.passive` objects contains the S-parameter, noise figure, and group delay values that are the result of analyzing the values stored in the `passive.s2p` file at the frequencies stored in this file. These frequency values are also stored in the `NetworkData` property. OIP3 is always ∞ for `rfckt.passive` objects because the data is passive.

• `rfckt.amplifier` — By default, the `AnalyzedResult` property of `rfckt.amplifier `objects contains the S-parameter, 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. These frequency values are also stored in the `NetworkData` property.

• `rfckt.mixer` — By default, the `AnalyzedResult` property of `rfckt.mixer `objects contains the S-parameter, noise figure, OIP3, and group delay values that result from analyzing the values stored in the `default.s2p` file at the frequencies stored in this file. These frequency values are also stored in the `NetworkData` property.

For a detailed explanation of how the `analyze` method calculates the network parameters, noise figure values, and OIP3 values for a particular object, see the `AnalyzedResult` property on the reference page for that object.

## Examples

collapse all

Create and analyze a two-wire network object.

``` tx1=rfckt.twowire('Radius',7.5e-4); analyze(tx1,1.9e9) ```
```ans = rfckt.twowire with properties: Radius: 7.5000e-04 Separation: 0.0016 MuR: 1 EpsilonR: 2.3000 LossTangent: 0 SigmaCond: Inf LineLength: 0.0100 StubMode: 'NotAStub' Termination: 'NotApplicable' nPort: 2 AnalyzedResult: [1x1 rfdata.data] Name: 'Two-Wire Transmission Line' ```

## References

https://www.microwaves101.com/encyclopedias/group-delay-measurements