replacements for SY89846UMG

Yes, input MUX isolation spec is in the datasheet.  It is good isolation performance since the 2 differential inputs are located on opposite sides of the chip.

Regards,

Alan

Foffset is the offset frequency between the selected input (victim) and the non-selected input (aggressor).  For example, if Fclkin0 = 100 MHz, then Fclkin1 = 100 MHz +/- 50 kHz (or greater).  We needed offset to be >50 kHz so the crosstalk sideband spur power level due to the aggressor input is clearly seen above the noise skirt of the measured fundamental output signal for the selected input. 

PclkinX is the reference input power levels used for the aggressor and victim inputs (both 0 dBm ).  If the aggressor input power level is increased relative to the 0 dBm reference, then the ISOmux spec should increase (get worse) by the same amount in dB.  For example, for CLKin0 = 100 MHz, 0 dBm (victim) and CLKin1 = 101 MHz, +2 dBm (aggressor), the input mux isolation would become -82 dBc (=-84 dBc typ spec + 2 dB aggressor power above 0 dBm reference levels).

To translate the ISOmux spec (i.e. phase spur power level, in dBc, induced by input mux crosstalk) to the equivalent "Crosstalk-Induced Jitter" spec, you can use the same formula as phase spur level induced by power supply noise (referred to as "PSRR" in the datasheet).

Deterministic Jitter (peak-to-peak) due to periodic noise signal:

DJ p-p = 2 * 10^(-|dBc|/20) / (pi * Fclk), where dBc is a single-sideband spur power level relative to carrier measured at the output induced by a single fundamental noise signal like power supply ripple or input mux crosstalk.

DJ p-p can be expressed as RMS value as shown below.

DJ rms = DJ p-p / (2 * sqrt(2))

SAMPLE CALCULATION:

For the ISOmux spec = -84 dBc @ Fclkin=100 MHz, Foffset>50kHz, Pclkin=0dBm conditions, this results in DJ = 0.4 ps p-p, or DJ = 0.14 ps rms.

Regards,
Alan