Continuous time Bandpass Complex DeltaSigma ADC Simulation

[payam_s]

bandpass delta sigma

Hello All,

I am about to design a CT/BP/Complex ΔΣ ADC . First I have designed a LP DT Real NTF then changed it to CT prototype next I've shifted the center freq. to 5 MHz. When I plot the NTF and STF it seems the filter property is ok. I have also extracted the ABCD matrix to be able to simulate the system in time domain.
But I have difficulties in simulating the system in time domain. I don't know how input(s) should look like. what should be the format of the input signal(s) into this complex system and also how should I do copmlex quantization? and finally how should be the format of the output in order to window it, take fft to plot and analyze the PSD. the codes and functions I used and defined to design NTF, converting to continuous time domain and shifting the frequency and also extracting the state-space matrices ABCD are available upon request to help you more how I did in my design flow to guide me with my questions.
Hope to hear from you soon

 

[santi001]

hi,

I am new to the sigam delta.
can you please help me wrt ABCD matrix.

How to get ABCD matrix for 2nd order sigma delta modulator.

I got the delta sigma tool box from
https://www.mathworks.com/matlabcentral/fileexchange

For a second order modulator the ABCD state space model is given as
A=[1 0; 1 1];
B=[1 -1; 1 -2];
C=[0 1];
D=[0 0];
ABCD=[A B; C D];

 

[payam_s]

Re: Continuous time Bandpass Complex DeltaSigma ADC Simulati

As you mentioned you have already extracted state-space matrices ABCD using delsig toolbox :!:
anyway, this matrices are usually used to get the impulse response and time domain analysis of delsig modulators, and later time domain samples are used to calculate SNR and draw PSD plots.