Diodes Incorporated FMMV2103TA

Overview

FMMV2103TA from ON Semiconductor is a silicon planar variable capacitance diode (varactor) in SOT-23 package, rated for 30 V reverse voltage, 10.0 pF nominal capacitance at 4 V/1 MHz, and 400 minimum Q-factor at 4 V/50 MHz; used in VCO tuning circuits for UHF FM radio front-ends.

For engineers reviewing the FMMV2103TA datasheet, FMMV2103TA pinout, FMMV2103TA application, or FMMV2103TA equivalent, key selection criteria include tuning ratio (2.6–3.3), temperature coefficient (280–400 ppm/°C), series inductance (3.0 nH), reverse leakage (20 nA @ 25 V), and case capacitance (0.15 pF).

Technical Context

This varactor diode operates under reverse bias only, with capacitance varying nonlinearly from ~11.0 pF at 2 V to ~3.5 pF at 30 V. Its low series inductance (3.0 nH) and controlled temperature coefficient support stable frequency pulling in oscillator tanks up to 500 MHz.

The device uses planar diffusion structure to minimize parasitic resistance and ensure repeatable C-V slope. Case capacitance of 0.15 pF is measured at 1 MHz and contributes directly to total tank capacitance in matching networks.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; standardized 3-pin outline (pin 1 = anode, pin 2 = cathode, pin 3 = case/thermal pad not electrically connected).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar varactor diode applications.

Compared with SMV2023-011LF and BBY52-02W, FMMV2103TA delivers optimal balance of mid-range capacitance, high Q, and industry-standard SOT-23 fit-making it ideal for cost-sensitive UHF consumer radio designs where 10 pF and ≥400 Q are required.

Availability

FMMV2103TA is available at Aetrix Electronics and suitable for FM radio tuners, wireless microphone transmitters, ISM band remote controls, and automotive keyless entry modules requiring stable component supply across extended temperature ranges.

Supply support for FMMV2103TA 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, and consumer markets.

FMMV2103TA belongs to the FMMV series of silicon planar varactors engineered for high-Q, low-inductance RF tuning in portable and battery-powered UHF communication devices.

FAQ

What is the recommended DC blocking configuration for FMMV2103TA in VCO designs?

A 100 pF NP0 ceramic capacitor in series with the anode is standard practice to prevent RF feedthrough into the tuning voltage rail. The cathode connects directly to the tank inductor's RF ground node. No additional series resistor is needed due to the device's low forward current rating and reverse-only operation.

Does FMMV2103TA require derating at elevated ambient temperatures?

Yes-power dissipation must be linearly derated above 25°C ambient: P_tot decreases by 2.64 mW/°C beyond 25°C, reaching zero at 150°C junction temperature. At 85°C ambient, maximum allowed dissipation is 165 mW, limiting tuning voltage swing in high-bias applications.

Can FMMV2103TA be used in forward bias mode?

No-FMMV2103TA is strictly a reverse-biased varactor. Forward conduction begins above 0.7 V and causes irreversible capacitance nonlinearity, increased leakage, and permanent degradation of Q-factor. Bias circuitry must guarantee cathode voltage exceeds anode voltage by ≥1 V at all times.

How does case capacitance affect matching network design?

The 0.15 pF case capacitance appears in parallel with the active junction capacitance and must be included in total tank calculations. In microstrip layouts, this value matches typical pad-to-ground coupling, so layout parasitics often compensate for it-reducing need for additional trim capacitors in production designs.