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gm ldo
thanks saro,
i am seeing the same volatge change in output as claculated from output impedence .(ie 100mV for 1mA @ ugb (50MHz) if output impedence is 100 (40dB)).
actually i was taking only single step earlier . if we take periodic load then the dip will becomes same as what perdicted...
ldo design
but why i am not getting the value corresponding to the output impedence value.
say i apply step of 1mA at the LDO output then i should get 100*1mA = 100mV change in output . i am seeing only 10mV change . i think the step signal does have all frequency component , so frequency...
ldo & ripple
my load current varies from 50uA to 20mA
the transient load applied is 50uA to 10mA in 50 ns.
the 20 db number is for 20mA , for 50uA (minimum load) the output impedence peaks to 30dB ..
ldo basics
i wanted to know what is the correlation between output impedence and LDO transient load performance . actually i am seening a peak of 20db impedence at around UGB of LDO (dc is only around 0 db). however when we apply transient LOAD the measured dip in LDO output is quit less than...
you can pump two diffirent current say 1uA and 10uA in two different BJT.
use relation VBE1 -VBE2 = nVt*ln(I1/I2).
so you just nedd to take the difference between two voltage and do a temperature DC sweep.
it should be simple linear line..as expected (Vt=kT/q)
you can take derivative to get...
Re: Bandgap Reference
generally bandgap also provide current reference (which can be 5-8%) accurate..
so best way is to bias through current(biasing is simpler and good control over power dissipation).. . also accuracy requirements for current is generally less compared voltage..
LDO are used...
use N-well resistors for high values,although area will still be high for Mohms..
generally MOS capacitors are used to implement cap of the order of pF.. u can try DRAM capacitor technology for high density....
digital modulation like QPSK ,GMSK are used. with different coding rate 1/2,3/4 based on BER..etc are used..
one of the reason might be very less SNR of signals to be processed.
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