There is a difference between successive approximation type DVM and linear ramp type DVM
|Successive approximation type DVM
||Linear ramp type DVM
|Unknown voltage is successfully compared with the output of digital to analog converter.
||Unknown voltage is compared with either positive or negative going ramp.
|Output reading is obtained after successive decision taken by logic circuit. So the probability of error in output reading is more.
||Probability of error in the output reading is less.
|Output signal cannot be easily digitized.
||Since the output is in terms of time, this signal can be easily digitized.
|Speed of operation is less.
||Speed of operation is more.
|Resolution upto maximum 5 digits can be obtained.
||Resolution is directly proportional to the frequency of local oscillator and it can be improved by increasing this frequency.
|Accuracy depends on accuracy of internal reference and accuracy of digital to analog converter.
||Accuracy depends on linearity and slope of ramp. As well as it depends on stability of local oscillator.