Diodes Incorporated FMMT918TC

Overview

FMMT918TC from Diodes Incorporated is an NPN silicon planar RF transistor in SOT23 package, rated for V_CEO = 15 V, I_C = 100 mA, and f_T = 600 MHz, designed for VHF/UHF amplifier and oscillator stages in wireless transceivers and signal conditioning circuits.

For engineers reviewing the FMMT918TC datasheet, FMMT918TC pinout, FMMT918TC application, or FMMT918TC equivalent, key selection criteria include transition frequency, noise figure at 60 MHz, saturation voltage under 10 mA drive, and SOT23 thermal performance in compact RF layouts.

Technical Context

This transistor employs a planar epitaxial structure optimized for high-frequency analog gain, with verified f_T = 600 MHz at I_C = 4 mA and V_CE = 10 V, and low C_obo = 1.7 pF at V_CB = 10 V enabling stable UHF operation. Its V_CEO(sus) = 15 V supports reliable switching in pulsed RF amplifiers.

The device exhibits V_BE(sat) = 1.0 V at I_C = 10 mA / I_B = 1 mA and h_FE = 20 minimum at I_C = 3 mA / V_CE = 1 V, confirming suitability for Class-A small-signal amplification with predictable DC biasing.

Key Specifications

Pinout & Package

SOT23-3 (TO-236AB) plastic surface-mount package with gull-wing leads; standard pin assignment per JEDEC TO-236: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN RF transistor applications.

Compared with MMBT918, FMMT918TC offers identical RF performance in the same package; versus 2SC3356, it trades bandwidth and voltage headroom for pinout compatibility and lower cost in legacy VHF/UHF designs.

Availability

FMMT918TC is available at Aetrix Electronics and suitable for VHF receiver front-ends, UHF oscillator cores, and RF driver stages requiring stable component supply and consistent SOT23 thermal behavior.

Supply support for FMMT918TC includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global semiconductor company specializing in discrete, analog, and mixed-signal solutions for industrial, computing, consumer, and communications markets.

FMMT918TC belongs to the FMMT series of high-frequency bipolar transistors engineered specifically for VHF/UHF amplification and oscillation in space-constrained RF modules.

FAQ

What is the maximum operating frequency for reliable small-signal amplification with FMMT918TC?

The FMMT918TC achieves unity gain at 600 MHz (f_T), and maintains usable power gain up to 200 MHz, where G_pe = 15 dB is specified at 200 MHz. For stable amplification, design should target ≤1/3 f_T (200 MHz) with proper neutralization and impedance matching.

Can FMMT918TC be used in switching applications?

Yes - its V_CE(sat) = 0.4 V at I_C = 10 mA / I_B = 1 mA and fast charge storage characteristics support low-duty-cycle RF switching. However, it is not optimized for digital logic-level switching due to moderate h_FE and lack of specified t_on/t_off parameters.

Is the SOT23 pinout for FMMT918TC standardized across manufacturers?

Yes - FMMT918TC follows JEDEC TO-236AB standard: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector. This matches Diodes Incorporated's MMBT918 and Zetex's ZTX918, ensuring direct PCB footprint compatibility without layout changes.

How does the 6.0 dB noise figure impact receiver sensitivity?

A 6.0 dB noise figure at 60 MHz increases system noise floor by ~4× relative to a 0 dB ideal amplifier, directly limiting minimum detectable signal. In a 136–174 MHz receiver with 10 kHz bandwidth, this corresponds to ≈ –115 dBm sensitivity before further degradation from subsequent stages.