MAX1213_09 Datasheet, PDF (17/19 Pages) Maxim Integrated Products – 1.8V, 12-Bit, 170Msps ADC for Broadband Applications

1.8V, 12-Bit, 170Msps ADC for
Broadband Applications
Static Parameter Definitions
Integral Nonlinearity (INL)
Integral nonlinearity is the deviation of the values on an
actual transfer function from a straight line. This straight
line can be either a best straight-line fit or a line drawn
between the end points of the transfer function, once
offset and gain errors have been nullified. However, the
static linearity parameters for the MAX1213 are mea-
sured using the histogram method with an input fre-
quency of 10MHz.
Differential Nonlinearity (DNL)
Differential nonlinearity is the difference between an
actual step width and the ideal value of 1LSB. A DNL
error specification of less than 1LSB guarantees no
missing codes and a monotonic transfer function. The
MAX1213’s DNL specification is measured with the his-
togram method based on a 10MHz input tone.
Dynamic Parameter Definitions
Aperture Jitter
Figure 11 depicts the aperture jitter (t_AJ), which is the
sample-to-sample variation in the aperture delay.
Aperture Delay
Aperture delay (t_AD) is the time defined between the
rising edge of the sampling clock and the instant when
an actual sample is taken (Figure 11).
CLKN
CLKP
ANALOG
INPUT
t_AD
t_AJ
SAMPLED
DATA (T/H)
T/H ^TRACK
HOLD
TRACK
Figure11. Aperture Jitter/Delay Specifications
Signal-to-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital
samples, the theoretical maximum SNR is the ratio of
the full-scale analog input (RMS value) to the RMS
quantization error (residual error). The ideal, theoretical
minimum analog-to-digital noise is caused by quantiza-
tion error only and results directly from the ADC’s reso-
lution (N bits):
SNR_[max] = 6.02 x N + 1.76
In reality, other noise sources such as thermal noise,
clock jitter, signal phase noise, and transfer function
nonlinearities are also contributing to the SNR calcula-
tion and should be considered when determining the
signal-to-noise ratio in ADC.
Signal-to-Noise Plus Distortion (SINAD)
SINAD is computed by taking the ratio of the RMS sig-
nal to all spectral components excluding the fundamen-
tal and the DC offset. In the case of the MAX1213,
SINAD is computed from a curve fit.
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio of RMS amplitude of the carrier fre-
quency (maximum signal component) to the RMS value
of the next-largest noise or harmonic distortion compo-
nent. SFDR is usually measured in dBc with respect to
the carrier frequency amplitude or in dBFS with respect
to the ADC’s full-scale range.
Intermodulation Distortion (IMD)
IMD is the ratio of the RMS sum of the intermodulation
products to the RMS sum of the two fundamental input
tones. This is expressed as:
⎛
IMD = 20 × log_{⎝⎜⎜}
V_IM12
+ V_IM2 ²
+ ...... + V_IM3 ²
+ V_IMn2
⎞
⎟
V₁₂ + V₂ ²
⎠⎟
The fundamental input tone amplitudes (V₁ and V₂) are at
-7dBFS. The intermodulation products are the amplitudes
of the output spectrum at the following frequencies:
• Second-order intermodulation products: f_IN1 + f_IN2,
f_IN2 - f_IN1
• Third-order intermodulation products: 2 x f_IN1 - f_IN2,
2 x f_IN2 - f_IN1, 2 x f_IN1 + f_IN2, 2 x f_IN2 + f_IN1
• Fourth-order intermodulation products: 3 x f_IN1 - f_IN2,
3 x f_IN2 - f_IN1, 3 x f_IN1 + f_IN2, 3 x f_IN2 + f_IN1
• Fifth-order intermodulation products: 3 x f_IN1 - 2 x f_IN2,
3 x f_IN2-2 x f_IN1, 3 x f_IN1+2 x f_IN2, 3 x f_IN2 + 2 x f_IN1
Full-Power Bandwidth
A large -1dBFS analog input signal is applied to an
ADC and the input frequency is swept up to the point
where the amplitude of the digitized conversion result
has decreased by 3dB. The -3dB-point is defined as
full-power input bandwidth frequency of the ADC.
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