Hi
i'm designing the circuit that want to achieve 16bit resolution or 65536 steps.
ADC input voltage rang = 4.096v
adc chip : max1169
1 step = 62.5 uV
i use 5k potentiometer between vcc and analog ground for create simple input signal to ADC and see the input changes in PC .
you can see circuit summary in here
.
i use the opamp buffer for Vin according to MAX1169 evaluation kit circuit and drive this ADC like the datasheet. but instead of (opamp) MAX4430 i use AD8055a that give me high slew rate value. and send the data value to the ARM at91sam7s64 . PC software receive data with COM port.
at the first time i had 200mv (3200 steps) ripple in output. but by using some tips, destructive effects of ripple and noise reduced to 2.75mv ( 44 steps).
at now i can reduce this value around to 1/3 or 0.9mv (14 steps) and next step to achieve to 1 step. but i have two problem.
problem 1 : when i use the battery i don't have a good dc output line (unstable) that you can see in the pictures :
battery is lipo 2cell 7.4v .
total circuit current = 50mA
but when i use power supply the output dc line (red line) have a good seems :
problem 2 : how to achieve from 14 step to 1 step (16bit resolution) ?
i'm designing the circuit that want to achieve 16bit resolution or 65536 steps.
ADC input voltage rang = 4.096v
adc chip : max1169
1 step = 62.5 uV
i use 5k potentiometer between vcc and analog ground for create simple input signal to ADC and see the input changes in PC .
you can see circuit summary in here
.
i use the opamp buffer for Vin according to MAX1169 evaluation kit circuit and drive this ADC like the datasheet. but instead of (opamp) MAX4430 i use AD8055a that give me high slew rate value. and send the data value to the ARM at91sam7s64 . PC software receive data with COM port.
at the first time i had 200mv (3200 steps) ripple in output. but by using some tips, destructive effects of ripple and noise reduced to 2.75mv ( 44 steps).
at now i can reduce this value around to 1/3 or 0.9mv (14 steps) and next step to achieve to 1 step. but i have two problem.
problem 1 : when i use the battery i don't have a good dc output line (unstable) that you can see in the pictures :
battery is lipo 2cell 7.4v .
total circuit current = 50mA
but when i use power supply the output dc line (red line) have a good seems :
problem 2 : how to achieve from 14 step to 1 step (16bit resolution) ?
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