求助 梯度误差对SFDR的影响

xiao3586906

梯度误差对SFDR的影响，用matlab仿真。

下图是我查阅资料时看到的，实线是Matlab通过计算公式绘制的。但是虚线的仿真部分怎么实现，我还没有思路，不知哪位大神能否详细讲讲。

hsh22

用google

xiao3586906

用google
hsh22 发表于 2011-3-23 21:10

                               
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    明显不行么。

fhchen2002

The idea is like the following:

SFDR should be examined by FFT (i.e., signal power over the next largest power of in the FFT bins).
For ideal N-bit DAC (un-biased, no mistmach between unit cells, without process gradient effects), the FSDR is ~ 8.2 N + 2.2 dBc.
Now simply model your unit-cells with process gradient in X and in Y directions.
You get bit-by-bit DAC total output based on the sum of the (biased) unit cells.

Stimulate the non-ideal DAC (modeled by MATLAB script, with process gradient) with sinasoidal "digital" input (an ideal analog input going through an ideal N-bit ADC reaching just the full-scale of the ADC), then you get non-ideal DAC outputs with the effect of gradients.  Send your DAC output to FFT routine to get the SFDR.

You should find that when the gradient is small, the SFDR examined by the FFT routine is close to 8.2 N + 2.2.  As the gradient gets larger and larger, the SFDR starts to degrade.

xiao3586906

The idea is like the following:

SFDR should be examined by FFT (i.e., signal power over the next  ...
fhchen2002 发表于 2011-5-19 20:04

                               
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    非常谢谢您，我先试试。有问题再请教