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nyquist sampling bandwidth adc
!! I thought sampling time should be twice of the carrier frequency, for the Nyquist theory.
Is it the twice of the bandwidth the lowest frequency for subsampling?
if sampling at 93.3 mhz aliasing
Could alias sampling truthfully track original signals?
I don't believe so.
But in datasheet for GP2015 and its series products, they use 5.714MHz to sample 4.309MHz signal and expect an almost idea output with 30% set high of the time.
As I simulate, with...
how many percent could rise and fall time exist in an sampling circuit?
Here it is used in the 2 bit AD in GPS circuit.
I think that depends on the sampling clock, signal clock and the baseband demodulation requirement.
Any formula to caculate this?
i try that circuit in the book too.
I use a large sinewave to do it.
The transient output rise and fall at different input voltage, I think this shows the hysteresis performance.
But I don't see oscillation.
you could use .measure to measure the noise voltage at needed frequency and .print+a formular for NF calculation. The formular depends on your netlist. The problem is how to make sure the formular is right.
noise in bandgap
THanks for your answer.
However though wideband reference is good for power supply rejection, here there is another probelm if the bandgap is for an amplifier. Cause if no enough filtering is offered, the circuit is tend to oscillate. Shouldn't the power supply ripples...
noise in bandgap
Hi, could you please explain about what dose the "accuracy more than about 8-bit using the Vref" mean?
And why should a bandgap circuit has bandwidth?
And why should the change in load affect a bandgap circuit? I think in most circuits they are quite independent from...
How to calculate of the requirement of Op-am when designing a filter?
It seems the wrong OP-amp might quite likely to fail the filter.
But how could we know what kind of Op-amps do we need?
gps 2 bits adc
I think 2 bits ADC is used in GPS system just cause it is a BPSK modulated system. 2 bits is enough to recover the info.
The 1 bit output might be a plus result of 2 bit original "mag" and "sign". But I never saw this in product datasheets.
Where do u see it?
What puzzles me is...
Well, it oscillate at smaller gain with 100uF.
With 1uF, it oscillates too, but the oscillation happens at higher gain.
Seems there must be a optimum cap value.
But I haven't found it.
But why should this happen??
I think caps are for filtering and are good for stability.
Do u mean do transient simulation with different common mode voltage?
And why THD is -3dB worse beyong common mode range?
I think THD is mostly related to the amplitude of the signal.
Could we just change the bias voltage of the differential amplifier and check its operating point?