AD6674 datasheet(32/91 Pages) AD

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AD6674

Data Sheet

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RMS CLOCK JITTER REQUIREMENT

ANALOG INPUT FREQUENCY (MHz)

Figure 91. Ideal SNR vs. Analog Input Frequency and Jitter

Treat the clock input as an analog signal in cases where aperture

jitter may affect the dynamic range of the AD6674. Separate

power supplies for clock drivers from the ADC output driver

supplies to avoid modulating the clock signal with digital noise.

If the clock is generated from another type of source (by gating,

dividing, or other methods), retime it using the original clock at

the last step. See the AN-501 Application Note and the AN-756

Application Note for more in-depth information about jitter

performance as it relates to ADCs.

Figure 92 shows the estimated SNR of the AD6674-1000 across

input frequency for different clock induced jitter values. The

SNR can be estimated by using the following equation:























 −











 −

10log

(dBFS)

JITTER

ADC

SNR

INPUT FREQUENCY (Hz)

10M

100M

10G

25fs

50fs

75fs

100fs

125fs

150fs

175fs

200fs

Figure 92. Estimated SNR Degradation for the AD6674-1000 vs.

Input Frequency and Jitter

POWER-DOWN/STANDBY MODE

The AD6674 has a PDWN/STBY pin that can be used to

configure the device in power-down or standby mode. The

default operation is the PDWN function. The PDWN/STBY pin

is a logic high pin. When in power-down mode, the JESD204B

link is disrupted. The power-down option can also be set via

In standby mode, the JESD204B link is not disrupted and

transmits zeros for all converter samples. This can be changed

using Register 0x571[7] to select /K/ characters.

TEMPERATURE DIODE

The AD6674 contains a diode-based temperature sensor for

measuring the temperature of the die. This diode outputs a

voltage and serve as a coarse temperature sensor to monitor the

internal die temperature.

The temperature diode voltage can be output to the FD_A pin

using the SPI. Use Register 0x028[0] to enable or disable the

diode. Register 0x028 is a local register. Channel A must be

selected in the device index register (Register 0x008) to enable

the temperature diode readout. Configure the FD_A pin to

output the diode voltage by programming Register 0x040[2:0].

See Table 45 for more information.

The voltage response of the temperature diode (with SPIVDD =

1.8 V) is shown in Figure 93.

TEMPERATURE (°C)

0.60

0.65

0.70

0.75

0.80

0.85

0.90

–55 –45 –35 –25 –15 –5

15 25 35 45 55 65 75 85 95 105 115 125

Figure 93. Temperature Diode Voltage vs. Temperature

Rev. B | Page 32 of 91

AD6674 Datasheet(PDF) 32 Page - Analog Devices

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