The BB 644 is a silicon variable capacitance diode from Dihao. It is mainly used in VHF TV tuners. The product features high capacitance ratio, low series inductance, low series resistance and extremely small plastic SMD package.
The BB 644 is a silicon variable capacitance diode offered by Siemens in an ultra‑small SOD‑323 surface‑mount package. It features a high capacitance ratio, low series inductance and resistance, and excellent uniformity for VHF TV‑tuner applications.
Key specifications include a reverse voltage rating of 30 V, forward current of 20 mA, operating temperature range from –55 °C to 4150 °C, and typical capacitance values of 39 pF at 1 V (1 MHz). The device also provides low series resistance (0.6 Ω at 1 GHz) and inductance (1.8 nH).
| Diode reverse voltage (Va) | 30 V |
|---|---|
| Peak reverse voltage (Vem) | 35 V |
| Forward current (If) | 20 mA |
| Operating temperature range | -55 … 4150 °C |
| Storage temperature range | -55 … 4150 °C |
| Typical reverse current (30 V) | 10 nA |
| Reverse current at 30 V, 85 °C | 100 nA |
| Capacitance ratio (2 V / 25 V, 1 MHz) | 11 |
| Series inductance (Ls) | 1.8 nH |
The diode can withstand a reverse voltage of up to 30 V.
It is rated for a forward current of 20 mA.
The device operates from –55 °C up to 4150 °C.