Datasheet

−120
−110
−100
−90
−80
−70
−60
−50
−40
−30
−20
−10
0
0 20 40 60 80 100
Frequency (MHz)
Amplitude (dB)
A
IN
= −1dBFS
SFDR = 88.5dBc
SNR = 78.2dBFS
SINAD = 77.6dBFS
THD = 85.3dBc
Coeff1 = 0x0
Coeff2 = 0x0
BW = 47.5MHz to 52.5MHz
ADS58B18
ADS58B19
SBAS487D – NOVEMBER 2009– REVISED JANUARY 2011 www.ti.com
SNR ENHANCEMENT USING SNRBoost (ADS58B18 ONLY)
SNRBoost technology makes it possible to overcome SNR limitations resulting from quantization noise. Using
SNRBoost, enhanced SNR can be obtained for any bandwidth (less than Nyquist or f
S
/2; see Table 4). SNR
improvement is achieved without affecting the default harmonic performance.
SNRBoost can be enabled using the SNRBoost_EN pin or via register bits. When SNRBoost is enabled, the
noise floor in the spectrum acquires a typical bathtub shape; see Figure 66. The bathtub is centered around a
specific frequency (called center frequency). The center frequency is located midway between two corner
frequencies that are specified by the SNRBoost coefficients (register bits SNRBoost Coeff1 and SNRBoost
Coeff2).
Figure 66. Spectrum with SNRBoost Enabled
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