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Simulators >> Circuit Simulators >> Could someone tell me how to simulate the SNR of a current-steering DAC?
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Message started by hotraymanf on Jan 7^th, 2009, 5:16pm

Title: Could someone tell me how to simulate the SNR of a current-steering DAC?
Post by hotraymanf on Jan 7^th, 2009, 5:16pm

I found there are some references using matlab. Is there someway to do it directly using spectre?

Thanks a lot! :)

Title: Re: Could someone tell me how to simulate the SNR of a current-steering DAC?
Post by ywguo on Jan 14^th, 2009, 6:16pm

It seems that you cannot calculate the SNR value in the Calculator when simulating with spectre.

Title: Re: Could someone tell me how to simulate the SNR of a current-steering DAC?
Post by sheldon on Jan 16^th, 2009, 7:39am

Greetings,

For a testbench, I use an ideal ADC created by modifying the
ideal8bitADC[?] from ahdlLib. By changing a variable in the VerilogA
code, any number of bits can be supported. Also you will need to
update the symbol to match the number of bits defined in the
VerilogA code. The ADC is driven by sine source. The clock frequency
is the same as the DAC clock frequency. The input, sine, frequency
is determined using the procedure outlined for selecting ADC test
frequencies in previous posts.

Assuming that you are using resistive loads to convert the current
back to voltage, then there are two options for analyzing the results.

Option 1: Waveform Calculator

To perform the standard measurements for data converters:
SINAD [SNDR], SNR, SFDR, ENOB, use the spectrum function
in the ViVA calculator. There is one item that you need to be
aware of, the spectrum function selects all the time domain
data for the FFT. So you will manually need to select the data
for the FFT using the clip function. An enhancement request
has been filed for this functionality.

NOTE:
You can use ViVA is stand-alone mode with simulation data
generated by IC5141, if you have the correct licenses and
the software installed.

Option 2: Fourier Integral

Unfortunately, this option only provides the SINAD. The reason
for mentioning it is that is since the "entire" waveform is considered.
As a result, the effect of glitch impulse is included in the analysis.
An FFT only samples the waveform, potentially using only one time
point per clock period. This might be useful later.

Best Regards,

Sheldon