3.1 pF at 3 V — the tuning element for VCOs and filters
The Infineon BBY5303WE6327HTSA1 is a single silicon varactor diode for voltage-controlled tuning in RF circuits. Its 3.1 pF capacitance at 3 V bias and 1 MHz sets the low-end capacitance of the LC tank; the 2.6 ratio (C1/C3) defines how far the oscillator can pull frequency as the tuning voltage swings. Peak reverse voltage is 6 V, which limits the maximum RF voltage swing across the diode before it forward-conducts and clips the tank. Stay below 6 V peak in the resonant circuit to keep the varactor in its reverse-biased tuning region.
-55 to 125 °C — rated for the harsh edge
This is not a commercial-grade part; it holds its capacitance vs voltage characteristic across the full temperature band, which matters for TCXO compensation and wide-temperature VCOs. The SOD-323 package (PG-SOD323-2) is a standard small-signal diode footprint, 2-pin, with the cathode marked by a band. Reflow profile follows standard lead-free solder with a 260 °C peak — no special handling beyond normal MSL 1 precautions.
Active production, RoHS3, and the BBY53-03 cross
Lifecycle status is Active — Infineon still manufactures this part, so no last-time-buy risk on the horizon. It is ROHS3 compliant, which means no exemptions for lead in solder or any of the six restricted substances beyond the standard RoHS thresholds. Both are single varactors in SOD-323 with the same 6 V peak reverse and similar capacitance range. If the exact BBY5303WE6327HTSA1 is tight on allocation, the BBY53-03 variant is a drop-in candidate — confirm the C-V curve matches your tuning target before committing the BOM.