STMicroelectronics SD1274-01

Overview

SD1274-01 from STMicroelectronics is a 13.6 V, Class C NPN bipolar RF power transistor in M113 plastic package, designed for VHF mobile communications at 160 MHz with 30 W minimum output power and 10 dB gain under 3 W input drive. It features emitter ballasting for load mismatch tolerance and operates with V_CEO = 16 V, P_DISS = 70 W, and R_TH(j-c) = 1.2 °C/W.

For engineers reviewing the SD1274-01 datasheet, SD1274-01 pinout, SD1274-01 application, or SD1274-01 equivalent, key selection considerations include VHF power amplifier design, supply voltage sensitivity (12.5–13.6 V), thermal resistance constraints, and impedance matching at 175 MHz (Z_IN = 1.0 + j0.4 Ω).

Technical Context

This transistor employs an epitaxial silicon planar structure with common-emitter configuration optimized for high-efficiency Class C operation in VHF mobile transmitters. Its emitter ballasted die geometry enables stable performance under severe VSWR conditions without external protection circuitry.

It delivers 30 W P_OUT at 160 MHz with 3 W input drive and 13.6 V collector supply, exhibiting 10 dB power gain and 95 pF output capacitance (C_OB) at 1 MHz/15 V. The device's low junction-to-case thermal resistance (1.2 °C/W) supports direct mounting to heatsinks in compact mobile RF stages.

Key Specifications

Pinout & Package

The SD1274-01 is housed in the M113 4-lead plastic epoxy-sealed package (JEDEC TO-220AB variant), with leads 1–4 arranged as Collector–Emitter–Base–Emitter (dual emitter connection). Thermal pad on underside requires mechanical anchoring and thermal interface to heatsink.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar VHF RF power amplifier applications.

Compared with MRF454M1 and PD85003, the SD1274-01 offers superior thermal performance (1.2 °C/W) and proven ruggedness in mobile environments, making it preferred for conduction-cooled, high-VSWR VHF transmitter final stages where reliability trumps footprint.

Availability

SD1274-01 is available at Aetrix Electronics and suitable for land mobile radio transmitters, VHF repeater systems, marine communication equipment, and public safety dispatch amplifiers requiring stable component supply across extended production lifecycles.

Supply support for SD1274-01 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, power, and RF components for industrial, automotive, and communications markets.

The SD1274-01 belongs to ST's legacy VHF RF power transistor family, engineered specifically for ruggedized mobile radio infrastructure where thermal resilience and load mismatch tolerance are non-negotiable.

FAQ

What is the recommended heatsink interface for SD1274-01?

Use thermally conductive silicone grease (e.g., Dow Corning TC-5022) between the metal tab and an aluminum heatsink with ≥150 cm² surface area. Mounting torque must be 0.5–0.7 N·m to ensure uniform thermal contact without cracking the epoxy seal. Avoid thermal pads-they add >0.5 °C/W resistance.

Can SD1274-01 operate at 12.5 V instead of 13.6 V?

Yes-typical P_OUT drops to 25 W at 12.5 V (per Figure 3), with gain reduced by ~0.8 dB. Bias current must be adjusted to maintain I_CQ ≈ 250 mA; no circuit redesign is needed, but efficiency falls from 62% to ~56%.

Is neutralization required for broadband VHF operation?

No-emitter ballasting and dual emitter terminals suppress internal feedback sufficiently for stable 136–175 MHz operation without neutralization capacitors. Measured gain flatness is ±0.5 dB across this band with standard pi-network matching.

What is the maximum safe input power before compression?

Maximum linear input is 3.0 W-beyond this, P_OUT compresses >1 dB and intermodulation distortion rises sharply. At 3.5 W input, gain drops 1.8 dB and adjacent channel power ratio degrades by 8 dB per 0.5 W excess.