stepresp

Step-signal response for rational object and rationalfit function object

Syntax

[outputsignal,tout] = stepresp(h,ts,n,trise)

Description

[outputsignal,tout] = stepresp(h,ts,n,trise) computes the time domain response of a rational function object, h, to a step signal based on the number of samples, n and the rise time, trise.

Examples

Calculate Step Response

Calculate the step response of a rational function object from the file passive.s2p. Read passive.s2p.

S = sparameters('passive.s2p');
freq = S.Frequencies;

Get S11 and convert to a TDR transfer function.

s11 = rfparam(S,1,1);
Vin = 1;
tdrfreqdata = Vin*(s11+1)/2;

Fit to a rational function object.

tdrfit = rationalfit(freq,tdrfreqdata);

Define parameters for a step signal. Define parameters for a step signal

Ts = 1.0e-11;
N = 10000;
Trise = 1.0e-10;

Calculate the step response for TDR and plot it

[tdr,t1] = stepresp(tdrfit,Ts,N,Trise);
figure
plot(t1*1e9,tdr)
ylabel('TDR')
xlabel('Time (ns)')

Input Arguments

h — Rational function object

rationalfit object | rational object

Rational function object, specified as a rationalfit or rational object.

Data Types: double
Complex Number Support: Yes

ts — Sample time of input signal

positive scalar integer

Sample time of the input signal, specified as a positive scalar integer in seconds.

Data Types: double

n — Number of samples

positive scalar integer

Number of samples, specified as a positive scalar integer.

Data Types: double

trise — Time taken for step signal to reach maximum value

positive scalar integer

Time taken for step signal to reach maximum value, specified as a positive scalar integer in seconds.

Data Types: double

Output Arguments

outputsignal — Computed step response

real finite vector

Computed step response, returned as a real finite vector.

Data Types: double

tout — Sample time of output signal

nonnegative vector

Sample time of the output signal, returned as a nonnegative vector of time values with discrete step size ts corresponding to the data in outputsignal in seconds.

Data Types: double

More About

Step Signal Equation

RF Toolbox™ uses the following equation to for the step signal:

$$\{\begin{array}{l}U(k{t}_s)=k{t}_s/t_{rise},\\ U(k{t}_s)=1,\end{array}\begin{array}{c}0\le k<\left(t_{rise}/t_s\right)\\ \left(t_{rise}/t_s\right)\le k\le N\end{array}$$

The following figure illustrates the construction of this signal.

Version History

Introduced in R2010a