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# ADF4118 Reference Input Sensitivity

Hi all,

In the datasheet specifications, Reference Input Sensitivity at ADF4118 & other ADF Integer-N is following.

"Reference Input Sensitivity 0.4 to AVDD  V p-p min to max AVDD = 3.3 V, biased at AVDD/2"

Other test condition is AVDD = 3 V.

Why is the test condition AVDD = 3.3 V ?  Is this typo ?

If is it true, what is the Reference Input Sensitivity  min / max spec. ?

Best regards,

sss

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• Hi,

I wonder if you may be confusing the condition at which the RF input sensitivity was characterized (AVDD = 3V) or what was used for AVDD during characterization as shown in the 'Specifications' section above Table 1 vs the conditions over which the REFERENCE input voltage is guaranteed (3.3V & 5.0V).

The ADF4118 datasheet actually lists the absolute max for AVDD as 7V (note that DVDD must be with in 0.3V of AVDD). In Table 1, when AVDD = 3.3V  (AC coupling results in the voltage swinging around a DC value equal to AVDD/2) the min & max V p-p values are guaranteed to be a minimum of 0.4V p-p min to 3.3V when operating from 5MHz to 100MHz.  These are the limits of the AC voltage swing and they are guaranteed by design which implies that they may not be tested in production as there is sufficient margin to guarantee this level of performance. Above 10MHz higher values of AVDD can be used and if a value equal to 5.0 Vp-p is used, the min & max V p-p values are guaranteed to be 0.7V pp to 5.0V pp. Lastly, at the top of Table 1, the 'Specifications' region indicates the settings that were used during characterization which yielded most of the RF  values shown in Table 1.  The fact that AVDD (and DVDD) were set to 3V during characterization would have had no impact on the REF input frequency range as this parameter would be characterized independently. Also note that RF input sensitivity (VCO input on pins 5 and 6) were obtained with AVDD equals 3V p-p. REFin (pin 8) was characterized at 3.3V, 5.0V and perhaps other values not shown in order to determine that we could guarantee the min / max voltage swing shown for each condition in Table 1.

Hope this helps,

Marty

• Marty - san,

Thank you for quick reply.

Our customer design at AVDD=DVDD=3.0V.

Conclusion, are Reference Input Sensitivity 3.0V spec and 3.3V spec the same specification, correct?

Reference Input Sensitivity 0.4 to AVDD V p-p min to max AVDD = 3.0 V, biased at AVDD/2 ?

Best regards,

sss

• Marty - san,

Thank you for quick reply.

Our customer design at AVDD=DVDD=3.0V.

Conclusion, are Reference Input Sensitivity 3.0V spec and 3.3V spec the same specification, correct?

Reference Input Sensitivity 0.4 to AVDD V p-p min to max AVDD = 3.0 V, biased at AVDD/2 ?

Best regards,

sss

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