THS1240 Datasheet, PDF (6/20 Pages) Texas Instruments – 12-BIT 40 MSPS IF SAMPLING COMMUNICATIONS ANALOG-TO-DIGITAL CONVERTER

THS1240
12-BIT 40 MSPS IF SAMPLING COMMUNICATIONS
ANALOG-TO-DIGITAL CONVERTER
SLAS279D – JUNE 2000 – REVISED JANUARY 2001
definitions of specifications
analog bandwidth
The analog input frequency at which the spectral power of the fundamental frequency of a large input signal
is reduced by 3 dB.
aperture delay
The delay between the 50% point of the rising edge of the clock and the instant at which the analog input is
sampled.
aperture uncertainity (jitter)
The sample-to-sample variation in aperture delay
differential nonlinearity
The deviation of any output code from the ideal width of 1 LSB.
integral nonlinearity
The deviation of the transfer function from an end-point adjusted reference line measured in fractions of 1 LSB.
Also the integral of the DNL curve.
clock pulse width/duty cycle
Pulse width high is the minimum amount of time that the clock pulse should be left in logic 1 state to achieve
rated performance; pulse width low is the minimum time clock pulse should be left in low state. At a given clock
rate, these specs define acceptable clock duty cycles.
offset error
The difference between the analog input voltage at which the ADC output changes from mid-scale to 1 LSB
above mid-scale, and the ideal voltage at which this transition should occur.
gain error
The difference between the analog input voltage at which the ADC output changes from full-scale to 1 LSB below
+ ^{* ǒ * Ǔ full scale, and the ideal voltage at which this transition should occur, minus the offset error}
2
Gain Error 100%x
V_IN) V_{IN_ @Code 4096}
2V
total harmonic distortion
The ratio of the power of the fundamental to a given harmonic component reported in dBc.
output delay
The delay between the 50% point of the falling edge of the clock and the time when all output data bits are within
valid logic levels (not including pipeline delay).
signal-to-noise-and distortion (SINAD)
When tested with a single tone, the ratio of the signal power to the sum of the power of all other spectral
components, excluding dc, referenced to full scale.
signal-to-noise ratio (SNR)
When tested with a single tone, the ratio of the signal power to the sum of the power of all other power spectral
components, excluding dc and the first 9 harmonics, referenced to full scale.
effective number of bits (ENOB)
For a sine wave, SINAD can be expressed in terms of the effective number of bits, using the following formula,
+ ^* ENOB
(SINAD 1.76)
6.02
spurious-free dynamic range (SFDR)
The ratio of the signal power to the power of the worst spur, excluding dc. The worst spurious component may
or may not be a harmonic. The ratio is reported in dBc (that is, degrades as signal levels are lowered).
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