Hello everyone,

is HMC830 compliant with a 40 MHz HCMOS external reference source?

If yes, what is the maximum amplitude? Is it always necessary to put a 100 Ohm resistor to ground for matching and an AC coupling capacitor in series?

Many thanks.

Regards,

Antonio L.

The HMC830 reference level must meet [0.6, 2.5] Vpp for a square wave or [6, 15] dBm for a sine wave (Table 3 in the Operating Guide). Usually 3.3V HCMOS drivers loaded with 50 ohms will meet this requirement. The external 100 ohm resistor in parallel with the internal 100 ohm resistance creates a 50 ohm load. You need the ac coupling cap to isolate the internal bias level from the HCMOS driver dc level.