3 vy14lvs24
Post on 19-Aug-2015
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Charge - Redistribution Successive Approximation
ADC
SYEDA NASIHA 3VY14LVS24
One of the most common implementation of successive approximation ADC.
It eliminates the need for separate sample and hold circuit.
The amount of charge on each capacitor of array is used to perform binary search operation
The conversion process begins by discharging capacitor array, via reset switch
Once the reset switch is closed, the capacitor array charges to the offset voltage of comparator.
The bottom plates of capacitors in array are connected to VIN
During hold mode reset is opened and bottom plates of capacitors are connected to ground.
Sampling VIN on capacitor array
The bottom plate of MSB capacitor is connected to Vref.
VTOP=-VIN+VOS+DN-1.VREF/2If output of comparator is high, the bottom plate of
MSB capacitor remains at VrefIf output of comparator is low, the bottom plate is
connected to ground
VTOP=-VIN+VOS+DN-1.VREF/2+DN-2.VREF/4
VTOP=-VIN+VOS+DN-1.VREF/2+DN-2.VREF/4+…….+ D1.VREF/2N-2+D0.VREF/2N-1=VOS
Redistribution(conversion)
THANK YOU
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