JAJSFK8C June 2018 – November 2018 LMX2615-SP
PRODUCTION DATA.
The choice of output buffer components is very important and can have a profound impact on the output power. The pull-up component can be a resistor or inductor or combination thereof. The signal swing is created is created by a current this pull-up, so a higher impedance implies a higher signal swing. However, as this pull-up component can be treated as if it is in parallel with the load impedance, there are diminishing returns as the impedance gets much larger than the load impedance. The output impedance of the device varies as a function of frequency and is a complex number, but typically has a magnitude on the order of 100 ohms, but this decreases with frequency.
The output can be used differentially or single-ended. If using single-ended, the pullup is still needed, and user needs to terminate the unused complimentary side such that the impedance as seen from the pin looking out is similar to the pin that is being used. Following are some typical components that might be useful.
COMPONENT | VALUE | PART NUMBER |
---|---|---|
Inductor | 1 nH, 13.6 GHz SRF | Toko LL1005-FH1N0S |
3.3 nH, 6.8 GHz SRF | Toko LL1005-FH3N3S | |
10 nH, 3.8 GHz SRF | Toko LL1005-FH10NU | |
Resistor | 50 Ω | Vishay FC0402E50R0BST1 |
Capacitor | Varies with frequency | ATC 520L103KT16T
ATC 504L50R0FTNCFT |