Electronic Components Datasheet Search |
|
AD676 Datasheet(PDF) 7 Page - Analog Devices |
|
AD676 Datasheet(HTML) 7 Page - Analog Devices |
7 / 16 page AD676 REV. A –7– NYQUIST FREQUENCY An implication of the Nyquist sampling theorem, the “Nyquist frequency” of a converter is that input frequency which is one half the sampling frequency of the converter. TOTAL HARMONIC DISTORTION Total harmonic distortion (THD) is the ratio of the rms sum of the harmonic components to the rms value of a full-scale input signal and is expressed in percent (%) or decibels (dB). For in- put signals or harmonics that are above the Nyquist frequency, the aliased components are used. SIGNAL-TO-NOISE PLUS DISTORTION RATIO Signal-to-noise plus distortion is defined to be the ratio of the rms value of the measured input signal to the rms sum of all other spectral components below the Nyquist frequency, includ- ing harmonics but excluding dc. GAIN ERROR The last transition should occur at an analog value 1.5 LSB be- low the nominal full scale (4.99977 volts for a ±5 V range). The gain error is the deviation of the actual difference between the first and last code transition from the ideal difference between the first and last code transition. BIPOLAR ZERO ERROR Bipolar zero error is the difference between the ideal midscale input voltage (0 V) and the actual voltage producing the midscale output code. DIFFERENTIAL NONLINEARITY (DNL) In an ideal ADC, code transitions are one LSB apart. Differen- tial nonlinearity is the maximum deviation from this ideal value. It is often specified in terms of resolution for which no missing codes are guaranteed. INTEGRAL NONLINEARITY (INL) The ideal transfer function for an ADC is a straight line bisect- ing the center of each code drawn between “zero” and “full scale.” The point used as “zero” occurs 1/2 LSB before the most negative code transition. “Full scale” is defined as a level 1.5 LSB beyond the most positive code transition. Integral nonlinearity is the worst-case deviation of a code center average from the straight line. BANDWIDTH The full-power bandwidth is that input frequency at which the amplitude of the reconstructed fundamental is reduced by 3 dB for a full-scale input. INTERMODULATION DISTORTION (IMD) With inputs consisting of sine waves at two frequencies, fa and fb, any device with nonlinearities will create distortion products, of order (m+n), at sum and difference frequencies of mfa ± nfb, where m, n = 0, 1, 2, 3. . . . Intermodulation terms are those for which m or n is not equal to zero. For example, the second or- der terms are (fa + fb) and (fa – fb), and the third order terms are (2 fa + fb), (2 fa – fb), (fa + 2 fb) and (fa – 2 fb). The IMD products are expressed as the decibel ratio of the rms sum of the measured input signals to the rms sum of the distortion terms. The two signals applied to the converter are of equal amplitude, and the peak value of their sum is –0.5 dB from full scale. The IMD products are normalized to a 0 dB input signal. APERTURE DELAY Aperture delay is the time required after SAMPLE pin is taken LOW for the internal sample-hold of the AD676 to open, thus holding the value of VlN. APERTURE JITTER Aperture jitter is the variation in the aperture delay from sample to sample. POWER SUPPLY REJECTION DC variations in the power supply voltage will affect the overall transfer function of the ADC, resulting in zero error and gain er- ror changes. Power supply rejection is the maximum change in either the bipolar zero error or gain error value. Additionally, there is another power supply variation to consider. AC ripple on the power supplies can couple noise into the ADC, resulting in degradation of dynamic performance. This is displayed in Figure 16. INPUT SETTLING TIME Settling time is a function of the SHA’s ability to track fast slewing signals. This is specified as the maximum time required in track mode after a full-scale step input to guarantee rated conversion accuracy. Definition of Specifications– |
Similar Part No. - AD676 |
|
Similar Description - AD676 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |