ISLA224S Datasheet, PDF (15/38 Pages) Intersil Corporation – Dual 14-Bit, 250/200/125 MSPS JESD204B High Speed Serial Output ADC

ISLA224S
CLKN
CLKP
RESETN
CAL_STATUS
BIT
CALIBRATION
BEGINS
CALIBRATION
TIME
CALIBRATION
COMPLETE
FIGURE 29. CALIBRATION TIMING
User Initiated Reset
Recalibration of the ADC can be initiated at any time by driving
the RESETN pin low for a minimum of one clock cycle. An
open-drain driver with a drive strength in its high impedance
state of less than 0.5mA is recommended, as RESETN has an
internal high impedance pull-up to OVDD. As is the case during
power-on reset, RESETN and DNC pins must be in the proper
state for the calibration to successfully execute.
Temperature Calibration
76
-2dBFS, 125MSPS
-1dBFS, 125MSPS
75
-2dBFS, 200MSPS
74
-1dBFS, 200MSPS
-2dBFS, 250MSPS
73
-1dBFS, 250MSPS
72
The performance of the ISLA224S changes with variations in
temperature, supply voltage or sample rate. The extent of these
changes may necessitate recalibration, depending on system
performance requirements. Best performance will be achieved
by recalibrating the ADC under the environmental conditions at
which it will operate.
A supply voltage variation of <100mV will generally result in an
SNR change of <0.5dBFS and SFDR change of <3dBc. In
situations where the sample rate is not constant, best results will
be obtained if the device is calibrated at the highest sample rate.
Reducing the sample rate by less than 80MSPS will typically
result in an SNR change of <0.5dBFS and an SFDR change of
<3dBc.
Figures 30 through 35 show the affect of temperature on SNR
and SFDR performance with power on calibration performed at
-40°C, +25°C, and +85°C. Each plot shows the variation of
SNR/SFDR across temperature after a single power on
calibration at -40°C, +25°C and +85°C. Best performance is
typically achieved by a user-initiated power on calibration at the
operating conditions, as stated earlier. However, it can be seen
that performance drift with temperature is not a very strong
function of the temperature at which the power on calibration is
performed.
90
-2dBFS, 125MSPS
85
-2dBFS, 200MSPS
-1dBFS, 125MSPS
80
-2dBFS, 250MSPS
-1dBFS, 200MSPS
71
-40
-35
-30
-25
-20
TEMPERATURE (°C)
FIGURE 30. TYPICAL SNR PERFORMANCE vs TEMPERATURE,
DEVICE CALIBRATED AT -40°C, f_IN = 105MHz
75
-40
-1dBFS, 250MSPS
-35
-30
-25
-20
TEMPERATURE (°C)
FIGURE 31. TYPICAL SFDR PERFORMANCE vs TEMPERATURE,
DEVICE CALIBRATED AT -40°C, f_IN = 105MHz
15
FN7911.0
December 20, 2011