n An integrating ADC is a type of analog-to-digital converter that converts an unknown input voltage into a digital representation through the use of an integrator. There are limits to the maximum resolution of the dual-slope integrating ADC. From the equation, one of the benefits of the dual-slope integrating ADC becomes apparent: the measurement is independent of the values of the circuit elements (R and C). In the worst case, nonlinearity or nonmonotonicity could result. The resolution obtained during the run-up period can be determined by making the assumption that the integrator output at the end of the run-up phase is zero. There may be conflicts if the next i/p is sampled before completion of one process. ): Note that this equation, unlike the equation for the basic dual-slope converter, has a dependence on the values of the integrator resistors. Integrating ADC‟s are of two types number of bits of resolution on x-axis and convention namely single slope ADC and dual slope ADC. signal community, called pipeline ADCs. {\displaystyle R_{d}} R The up and down more accurately refer to the process of adding charge to the integrator capacitor during the run-up phase and removing charge during the run-down phase. n A comparator is connected to the output to compare the integrator's voltage with a threshold voltage. / In order for the reference voltage to ramp the integrator voltage down, the reference voltage needs to have a polarity opposite to that of the input voltage. {\displaystyle CV_{out}} , can contribute the following charge, and {\displaystyle N} Disadvantages: 1)It is not suitable for higher number of bits. When using run-up enhancements like the multi-slope run-up, where a portion of the converter's resolution is resolved during the run-up phase, it is possible to eliminate the run-down phase altogether by using a second type of analog-to-digital converter. The basic principle of this type of A/D converter is that the unknown analog input voltage is approximated against an n-bit digital value by trying one bit at a time, beginning with the MSB. This page was last edited on 17 November 2020, at 13:09. {\displaystyle V_{\text{in}}} ), the difference will equal the smallest resolvable quantity. Although the integrating capacitor need not be perfectly linear, it does need to be time-invariant. The increase in ... 2. will cause the output of the integrator to go down. {\displaystyle N_{p}} V p {\displaystyle R_{n}} ... the source is first digitized for transmission through an analog to digital converter and is then reconstructed into … R A number of modifications to the basic design have been made to overcome these to some degree. d This type of calibration would be performed every time the converter is turned on, periodically while the converter is running, or only when a special calibration mode is entered. switch. = Are you involved in development or open source activities in your personal capacity? B What is the WPS button on a wireless router? For example, a sound picked up by a microphone into a digital signal. This also implies that the time of the run-up period and run-down period will be equal ( Then the ADC discharges the capacitor at a fixed rate while a counter counts the ADC's output bits. d Each has its own advantages and disadvantages and thus suitability for certain applications. o As explained below, the choice of the base affects the speed of the converter and determines the number of slopes needed to achieve the desired resolution. This still allows the same total amount of charge accumulation, but it does so over a smaller period of time. This is often done internal to the converter itself by periodically taking measurements of the ground potential. By combining some of these enhancements to the basic dual-slope design (namely multi-slope run-up and the residue ADC), it is possible to construct an integrating analog-to-digital converter that is capable of operating continuously without the need for a run-down interval. {\displaystyle R_{n}} : Substituting this back into the equation representing the run-down time required for the second and subsequent slopes gives us this: Which, when evaluated, shows that the minimum run-down time can be achieved using a base of e. This base may be difficult to use both in terms of complexity in the calculation of the result and of finding an appropriate resistor network, so a base of 2 or 4 would be more common. The controller keeps track of how often each switch is turned on in order to estimate how much additional charge was placed onto (or removed from) the integrator capacitor as a result of the reference voltages. An Analog to Digital Converter (ADC) converts an analog signal into a digital signal. Dual Slope converter. It is not possible to increase the resolution of the basic dual-slope ADC to arbitrarily high values by using longer measurement times or faster clocks. The main disadvantage of dual slope adc or integrated type adc What is the first and second vision of mirza? and [9] Conceptually, the multi-slope run-up algorithm is allowed to operate continuously. R {\displaystyle R_{d}/100} Disadvantages •The circuit is complex •Speed limited to ~5Msps 8. 1000 B Dual-slope ADCs are used in applications demanding high accuracy. The combination of the run-down times for each of the slopes determines the value of the unknown input. The value of the capacitor and conversion clock do not affect conversion accuracy, since they act equivalently on the up-slope and down-slope. The slope and intercept are the two specifications that define the transfer function of the log amp, that is, the relationship between output voltage and input signal level. N (charge balance dual slope ADC). , in terms of the base and the required resolution, V tFIX. Some examples of ADC usage are digital volt meters, cell phone, thermocouples, and digital oscilloscope. {\displaystyle t_{\Delta }} using the following equation (derived from the multi-slope run-up output equation): This equation represents the theoretical calculation of the input voltage assuming ideal components. 100 An Analog to Digital Converter (ADC) converts an analog signal into a digital signal. 1. The basis of this design is the assumption that there will always be overshoot when trying to find the zero crossing at the end of a run-down interval. u A longer discharge time results in a higher count. Some of this error can be reduced by careful operation of the switches. {\displaystyle R_{p}} Thus, this is all about counter type AD, its advantages, and disadvantages. o A calibration factor is typically included in the State the advantages of dual slope ADC . ) and that the total measurement time will be n The accurate correspondence of this ADC’s output with its input is dependent on the voltage slope of the integrator being matched to the counting rate of the counter (the clock frequency). Positive and negative reference voltages controlled by the two independent switches add and subtract charge as needed to keep the output of the integrator within its limits. p is necessarily an integer and will be less than or equal to selects the steepest slope (i.e., will cause the integrator output to move toward zero the fastest). When comparing the conversions from digital-to-analog and analog-to-digital, the A/D conversion is generally: The dual-slope ADC has many advantages. 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