The NXP BB174X is a single VHF varactor diode in a SOD-523 surface-mount package. It is built for voltage-controlled tuning in VHF oscillators and filters. The 30 V peak reverse rating sets the tuning voltage ceiling, and the 2.22 pF at 28 V gives the tank capacitance at the high end of the bias range. The capacitance ratio of 10.9 (C1/C28) indicates the tuning range.
Package and mounting
The 2.22 pF at 28 V is the capacitance at full reverse bias — that's your minimum capacitance for the LC tank. The 10.9 ratio means you get roughly a 10.9:1 frequency sweep in the oscillator, which is typical for VHF varactors. If you need a wider sweep, you'd look at a different diode family; if you need tighter linearity, you'd check the C-V curve. The -55 to 125 °C operating range covers military and industrial environments — avionics, satellite receivers, downhole telemetry — where the board sees temperature swings.
Package and mounting
SOD-523 is a tiny two-lead package. Surface-mount only. The Tape & Reel or Cut Tape option feeds into a pick-and-place for volume builds, or you can grab a cut tape for prototype runs. Keep the traces short to the tank circuit to minimize parasitic inductance at VHF.
Lifecycle and sourcing
No end-of-life notice has been issued. If you are freezing a BOM, this one is not going away soon.