![extreme sample converter manual sampling extreme sample converter manual sampling](https://i.ytimg.com/vi/pZ0xgJDcC6Q/maxresdefault.jpg)
It is related to the accuracy and the stability of the reference voltage, and of the ramp and clock generators. The accuracy of this type of converter is bad. The conversion process is schematically presented in Figure 2.38b. The clock is disconnected from the “clock” input of the counter and the latter stops counting. The output of the XOR gate shifts to a low state.
![extreme sample converter manual sampling extreme sample converter manual sampling](https://ars.els-cdn.com/content/image/3-s2.0-B9780750657983500023-f02-04-9780750657983.jpg)
At this time, the outputs of the two comparators C 1 and C 2 are high.
![extreme sample converter manual sampling extreme sample converter manual sampling](https://rekkerd.org/img/articles/extreme_sample_converter_32.png)
The amplitude of voltage v s (ramp-form signal) will continue to evolve until the moment it reaches and slightly exceeds the value zero. From this time onwards, the clock of the analog-to-digital converter is directly applied to the “clock” input of the counter and will begin its counting activity. Under these conditions, the output of the “exclusive OR” (XOR) gate is in high state. The counter is inactive.Īt the time when the amplitude of voltage v s reaches and slightly exceeds the amplitude of the analog sample E an, the output of comparator C 1 is high, while the output of comparator C 2 is low. As long as the amplitude of voltage v s is less than the amplitude of the analog sample E an, the outputs of the two comparators are low. The ramp-shaped signal is compared using two comparators C 1 and C 2 at all times to the analog signal E an to be converted and a threshold voltage equal to zero. Therefore, to convert an analog signal regardless of its polarity, it is necessary to use a ramp with both positive and negative amplitudes. Obviously, when the signal to be converted is positive, the ramp must have a positive part. When the analog voltage to be converted is negative, it is imperative that the ramp-shaped signal v s should have a negative part for the system to operate and obtain a result for the conversion. The operation of the analog-to-digital converter single-ramp can be established as follows.