groupdelay

Group delay of S-parameter object or RF filter object or RF Toolbox circuit object

Syntax

gd = groupdelay(sparamobj)

gd = groupdelay(sparamobj,i,j)

gd = groupdelay(rfobj,freq)

gd = groupdelay(rfobj,freq,Name,Value)

Description

gd = groupdelay(sparamobj) calculates the group delay of an S-parameter object at the frequencies specified in the S-parameter object file. sparamobj can be an S-parameters object or an nport object.

gd = groupdelay(sparamobj,i,j) calculates the group delay of a specific Sij. If i, j are not specified, the group delay is calculated for S21 for two-port objects and S11 for non-two-port objects.

gd = groupdelay(rfobj,freq) calculates the group delay of an RF Toolbox™ network object, rfobj, at the specified frequencies.

gd = groupdelay(rfobj,freq,Name,Value) calculates the group delay using additional options specified by one or more name-value pair arguments.

Example: gd = groupdelay (filter, frequency, 'Aperture', 50)

Examples

Group Delay of RLC Notch Filter

Calculate and plot the group delay of an RLC notch filter at the frequency range of 10–1000 MHz.

filt = circuit('notch');
add(filt,[1 2],resistor(200));
add(filt,[1 2],inductor(100e-9));
add(filt,[1 2],capacitor(25e-12));
setports(filt,[1 0],[2 0]);
freq = 10e6:10e4:1000e6;
gd = groupdelay(filt,freq);
figure
plot(freq,gd)

Group Delay of S-Parameter Data File

Find and plot the group delay from the specified Touchstone® file.

S = sparameters('defaultbandpass.s2p');
freq = S.Frequencies;
gd = groupdelay(S,freq);
figure
plot(freq,gd)

Group Delay of RF Filter Object

Calculate and plot the group delay of an RF Filter object at the frequency range of 0.5 - 3.5 GHz.

r = rffilter('FilterType','Butterworth','ResponseType',"Bandpass");
freq = linspace(0.5e9,3.5e9,1001);
gd  = groupdelay(r,freq);
plot(freq/1e9,gd)
xlabel('Frequency (GHz)');
ylabel('Group delay (seconds)');

Group Delay and Noise Figure of Two-Wire Transmission Line

Create a two-wire transmission line using these specifications:

• Radius - 0.5 mm

• Dielectric - air

• Thickness of dielectric or separation - 1.088 mm

• Permittivity or EpsilonR - 1.0054

twowiretxline = txlineTwoWire('Radius',0.5e-3,'EpsilonR',1.0054,'Separation',1.088e-3);

Calculate the noise figure and the group delay of the transmission line at 2.5 GHz.

nf = noisefigure(twowiretxline,2.5e9)

nf = 
0

gd = groupdelay(twowiretxline,2.5e9)

gd = 
3.3446e-11

Input Arguments

sparamobj — S-parameter object

object

S-parameter object. The function uses the data in the object to calculate the group delay.

Example: sparamobj = sparameters('defaultbandpass.s2p')

rfobj — RF object

circuit object | rffilter object | transmission line object | seriesRLC object | shuntRLC object | RF network objects

RF object, specified as one of the following:

Circuit object	circuit
RF Filter object	rffilter and lcladder.
Transmission line objects	txlineCoaxial txlineCPW txlineMicrostrip txlineLumped txlineParallelPlate txlineRLCGLine txlineTwoWire txlineEquationBased txlineDelayLossless txlineDelayLossy txlineElectricalLength txlineStripline
Series and Shunt RLC objects	seriesRLC, and shuntRLC
RF Network objects	For complete list of RF network objects see, RF Network Parameter Objects.

freq — Frequencies at which group delay is calculated

vector of positive real numbers

Frequencies at which group delay is calculated, specified as a vector of positive real numbers.

i,j — Port numbers of S-parameter object or RF object

scalar integers

Port numbers of S-parameter object or RF object, specified as scalar integers.

Example: S12

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: gd = groupdelay (filter, frequency, 'Aperture', 50)

Aperture — Width of two frequency points

freq*sqrt(eps) (default) | real, positive, numeric scalar or vector

Width of two frequency points, specified as the comma-separated pair consisting of 'Aperture' and a real, positive, numerics scalar or vector.

Example: 'Aperture',50

Data Types: double

Impedance — Impedance of S-parameters

real, positive, scalar

Impedance of S-parameters, specified as the comma-separated pair consisting of 'Impedance' and a real positive numeric scalar. The default impedance values for different objects are:

• 50 — LC ladder and circuit objects

• obj.impedance — S-parameter objects

• obj.networkdata.impedance — N-port objects

Example: 50

Data Types: double

Output Arguments

gd — Group delay

numeric scalar

Group delay, returned as a numeric scalar in seconds.

Version History

Introduced in R2015b

R2023a: Calculate group delay of transmission line lumped element

Specify a txlineLumped object in rfobj to calculate the group delay of the transmission line lumped element.