 # dual slope adc advantages and disadvantages

## dual slope adc advantages and disadvantages

For this reason, these converters are not found in audio or signal processing applications. There are limits to the maximum resolution of the dual-slope integrating ADC. The triple-slope architecture (see References 6-8) retains the advantages of the dual-slope, but greatly increases the conversion speed at the cost of added complexity. R Then, during the run-down, the first slope subtracts a large amount of charge, the second slope adds a smaller amount of charge, etc. d p V N V n Successive approximation ADC Much faster than the digital ramp ADC because it uses digital logic to converge on the value closest to the input voltage. with each subsequent slope moving a smaller amount in the opposite direction of the previous slope with the goal of reaching closer and closer to zero. To handle both positive and negative input voltages, a positive and negative reference voltage is required. Any of these variations result in error in the output of the converter. Main disadvantage of dual slope integrating type of ADC? R In the case of the basic design, the output of the converter is in terms of the reference voltage. N {\displaystyle R_{d}/100} {\displaystyle R_{n}} 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. {\displaystyle N_{p}=1,N_{n}=N-1} Resolution is limited by: The basic design of the dual-slope integrating ADC has a limitations in linearity, conversion speed and resolution. If you forget everything else we covered so far, remember that. Then a known reference voltage of opposite polarity is applied to the integrator and is allowed to ramp until the integrator output returns to zero (the run-down period). {\displaystyle T_{\text{first}}} applications having higher resolution and relatively Fig 12 shows the comparision based on slow conversions. The logic diagram for the same is shown below. d o , in terms of the base and the required resolution, , {\displaystyle N_{p}} switch. is the number of slopes. Note that in the graph to the right, the voltage is shown as going up during the run-up phase and down during the run-down phase. {\displaystyle B} V 1000 {\displaystyle V_{in}} p Dual-Slope. For example, a sound picked up by a microphone into a digital signal. However, the sampling time can be improved by sacrificing resolution. is the number of periods in which the negative reference is switched in, and What is the first and second vision of mirza? ... the source is first digitized for transmission through an analog to digital converter and is then reconstructed into … How long will the footprints on the moon last? The accuracy of the comparator used as the null detector. Activating each switch a constant number of times makes the error related to switching approximately constant. Each slope adds or subtracts known amounts of charge to/from the integrator capacitor. / {\displaystyle R_{d}/1000} Operation: t. The sampled signal charges a capacitor for a fixed amount of time ; By integrating over time, noise integrates out of the conversion. d The range of the integrating amplifier. It is also used to convert high bit-count, low-frequency digital signals into lower bit-count, higher-frequency digital signals as part of the process to convert digital signals into analog as part of a digital-to-analog converter (DAC). {\displaystyle V_{\text{in}}} = Each slope adds or subtracts a quantity of charge proportional to the slope's resistor and the duration of the slope: T Generalizing this, we can represent the number of slopes, . is the number of periods in which the positive reference is switched in, What does it mean when there is no flag flying at the White House? To conclude, dual slop integration type ADCs do not offer high speed conversion, but are highly reliable and effective when used with applications that tend to give out noisy signals. Are you involved in development or open source activities in your personal capacity? In this case, if we solve the above equation for Serial ADC Dual Slope • First: V IN is integrated for a fixed time (2NxT C 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. State the advantages of dual slope ADC . B The digital signal is represented with a binary code, which is a combination of bits 0 and 1. Thus, this is all about counter type AD, its advantages, and disadvantages. 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 R_{d}/100} Their use is typically limited to digital voltmeters and other instruments requiring highly accurate measurements. If we assume that the converter switches from one slope to the next in a single clock cycle (which may or may not be possible), the maximum amount of overshoot for a given slope would be the largest integrator output change in one clock period: To overcome this overshoot, the next slope would require no more than Some calibration can be performed internal to the converter (i.e., not requiring any special external input). Is Betty White close to her stepchildren?  In particular, during the run-up period, each switch should be activated a constant number of times. During the run-up phase, the switch selects the measured voltage as the input to the integrator. An Analog to Digital Converter (ADC) converts an analog signal into a digital signal. For a full-scale input equal to the reference voltage, half of the measurement time is spent in the run-up phase. , is always applied to the integrator. Engineering in your pocket. At the start of the run-down interval, the unknown input is removed from the circuit by opening the switch connected to N What is the WPS button on a wireless router? This does not mean, however, that the values of R and C are unimportant in the design of a dual-slope integrating ADC (as will be explained below). 0 are necessarily smaller than There may be conflicts if the next i/p is sampled before completion of one process. This is the main drawback of dual slope ADC . 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. is the maximum number of clock periods for the first slope, V N The required resolution (in number of bits) dictates the minimum length of the run-down period for a full-scale input ( o 100 {\displaystyle N} i and {\displaystyle N} The integrator is allowed to ramp for a fixed period of time to allow a charge to build on the integrator capacitor. = 23. clock The figure shows the transfer function at 900 MHz, and over temperature, of the AD8313 , a 100-MHz-to-2.5-GHz 65-dB log amp. Ideally, measuring the ground should always result in a zero output. Inputs to the controller include a clock (used to measure time) and the output of a comparator used to detect when the integrator's output reaches zero. Of these types of error, offset error is the simplest to correct (assuming that there is a constant offset over the entire range of the converter). The digital signal is represented with a binary code, which is a combination of bits 0 and 1. t {\displaystyle V_{\text{max}}} The output of the comparator is used by the converter's controller to decide which reference voltage should be applied. Assuming that multi-slope run-up as described above is being used, the unknown input voltage can be related to the multi-slope run-up counters, switch. The block diagram of an ADC is shown in the following figure −. / Instead of using a traditional run-down phase to determine this unknown charge, the unknown voltage can be converted directly by a second converter and combined with the result from the run-up phase to determine the unknown input voltage. N values: The resolution can be expressed in terms of the difference between single steps of the converter's output. The basic conversion principle of the ADC is divided into four processes. Typically, the run down time is measured in clock ticks, so to get four digit resolution, the rundown time may take as long as 10,000 clock cycles. in 1 Define conversion time. Question: ( Dual Slope ADC Present Advantages (1) Noise On The Input Voltage Is Reduced By Averaging (11) The Value Of The Capacitor And Conversion Clock Do Not Affect Conversion Accuracy - (!!)