Dual varactor in a small SOT-23 — what the ratings mean for your VCO or filter
The Infineon BB844E6327HTSA1 is a dual common-cathode silicon varactor diode in a three-pin SOT-23-3 package (PG-SOT23). It is designed for voltage-controlled oscillator (VCO) tuning, phase-shift networks, and bandpass filter adjustment where a predictable capacitance-versus-voltage curve is needed. The 3.8 capacitance ratio (C2/C8) gives a useful tuning range for a 2:1 frequency sweep in LC tank circuits. At 8 V reverse bias the capacitance measures 13 pF (at 1 MHz), and the peak reverse voltage rating of 18 V sets the upper limit of the tuning control voltage. The junction temperature range of -55°C to 150°C covers automotive under-hood and industrial process-control environments where the diode sees conducted heat from nearby power stages or a hot enclosure.
Active lifecycle — no last-time-buy pressure
There is no announced last-time-buy window, so the part is safe to specify for new production builds and for sustaining legacy BOM lines.
Package and mounting — SOT-23-3 with common cathode
The three-lead SOT-23-3 (PG-SOT23) houses two varactors with a shared cathode. The common cathode is the centre pin in the standard SOT-23 pinout; the two anodes are the outer pins. Surface-mount soldering follows standard SOT-23 reflow profiles. The -55°C to 150°C junction rating means the part can be placed near hot components — a 1 W resistor or a linear regulator dissipating into the board — without derating the tuning capacitance. No heatsinking is needed; the junction-to-ambient thermal path through the small leadframe is adequate for the low bias currents (microamps) typical of varactor operation.