BF1205,135

Overview

The BF1205 is a dual N-channel dual gate MOS-FET in an SOT363 package. It integrates two low noise gain controlled amplifiers with shared source and gate leads. One amplifier features fully integrated bias, while the other has partly integrated bias. The device includes an internal switch operated by the gate 1 bias of amplifier b to reduce external components. Key electrical parameters include a drain-source voltage limit of 10 V, a DC drain current of 30 mA, and total power dissipation of 200 mW. Forward transfer admittance is typically 63 mS at 12 mA drain current. Input capacitance ranges from 1.8 pF to 2.5 pF depending on the amplifier section.

Feature Summary

• Combines two equal dual gate MOS-FET amplifiers with shared source and gate leads within a single micro-miniature plastic package.
• Features an integrated switch operated by the gate 1 bias of amplifier b to minimize the number of required external components.
• Includes internal bias circuits that enable DC stabilization and superior cross-modulation performance during automatic gain control operations.
• Equipped with integrated diodes between the gates and source to protect against excessive input voltage surges.

Applications

• Gain controlled low noise amplifiers for VHF and UHF applications
• Digital television tuners
• Analog television tuners
• Professional communications equipment

Procurement Notes

Verify the specific ordering suffix to confirm packaging format, as standard designations may vary between tape-and-reel and cut-tape options. Confirm the component status, as availability can change over time. Ensure the sourcing channel provides valid manufacturer documentation to verify authenticity. Check for any specific handling requirements related to electrostatic discharge protection during transport and assembly processes.

Selection Notes

Select this component for designs requiring dual independent low noise amplification in a compact surface-mount footprint. The integrated switching capability simplifies circuit topology by reducing external control logic requirements. Consider the thermal resistance characteristics when designing heat dissipation strategies for high ambient temperatures. Verify that the operating frequency range aligns with the specified forward transfer admittance and noise figure performance curves.

Part Context

This device belongs to the discrete semiconductor category, specifically RF MOSFET transistors manufactured by NXP Semiconductors. It is designed for radio frequency applications where low noise and high linearity are critical. The SOT363 package allows for efficient use of printed circuit board space in portable and professional electronic devices.

Replacement Considerations

Check for direct pin-compatible alternatives within the same manufacturer's portfolio that offer similar dual-gate configurations. Verify that any substitute component matches the SOT363 package dimensions and electrical specifications for drain-source voltage and current ratings.

FAQ

How is the internal switch in the BF1205 controlled?

The internal switch is operated by the gate 1 bias of amplifier b. When VGG is set to 5 V, amplifier a is turned off and amplifier b is on. When VGG is 0 V, amplifier a is on and amplifier b is off.

What protection mechanisms are included in the BF1205?

The transistor includes integrated diodes between the gates and the source to protect against excessive input voltage surges.

What is the typical forward transfer admittance of the BF1205?

The typical forward transfer admittance is 63 mS when the drain current is 12 mA and the junction temperature is 25 °C.