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Re: multi bit quantizer in matlab
If you want to get 20.625 divider value, and the DSM is MASH 1-1-1. Then your divider must divide from 16~23.
The divider must be a mutimodulus divider. It can be made by a dual-modulus prescaler+P/S Counter or other medthods.
About building an adder
If I build a 20-bit adder with transisters in analog library (because I don't have digital library), is it much different from the adder building with digital standard cell? And what should I pay attention to build it? When it is finished, how can I simulate to make sure...
sigma delta modulator
I think eejli talking about a digital delta-sigma modulator. It may be used in a fractinal-N frequency synthesizer or a DA converter.
sigma delta modulator site:edaboard.com
See sth about FFT. Just do a FFT to the transient results, you will get the spectrum.
Added after 1 minutes:
See sth about FFT and window function. Just do a FFT to the transient results, you will get the spectrum.
About building an adder
If I build a 20-bit adder with transisters in analog library (because I don't have digital library), is it much different from the adder building with digital standard cell? And what should I pay attention to build it? When it is finished, how can I simulate it easily...
Thanks! Are there any other methods? I remember some paper mentioned cascading 3 D-flipflops to form a ring oscillator, I want to know more about this or methods like this.
Thanks! I know the PLL Fref is the frequency it works.(The real working frequecny should be the divided vco frequency,right?) I want to know if my Fref is about 20MHz, does it need special adder? Or normal adder can reach it? And how about 4th-order MASH?
A 3-order MASH modulator in fractional-N pll, each stage uses a 20-bit accumulator. How fast can it work? And generally what frequency does it work at?
Thanks!
Can anyone help me?
And another question. How to design the dividers(P_counter and S_counter) after prescaler? I means use verilog codes or design it by myself? And the counters are synchronous or asychronous?
The center freq. of VCO is 1.8G, so for fractional pll frequency synthesizer, 8/9 and 16/17 prescaler, which one is better choice? (Fref is 26MHz, when 16/17 prescaler is used ,the Fref is divided by 4).
delta sigma modulator with feedback
What do you mean? e.g. a 20bit input, it stands for between 0...1 or 0...7? And when you substract the filtered LSBs, substraction is used, you should use 2's complemenary, and so how to use only positive inputs?
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