STMicroelectronics SD1727

Overview

SD1727 from STMicroelectronics is a 50 V, 150 W PEP NPN RF power bipolar transistor optimized for HF SSB communications at 30 MHz, featuring common-emitter configuration, gold metallization, and –30 dBc IMD performance under 14 dB gain conditions in Class AB operation.

For engineers reviewing the SD1727 datasheet, SD1727 pinout, SD1727 application, or SD1727 equivalent, key selection criteria include rugged emitter-ballasted construction for transient overload tolerance, junction-case thermal resistance of 0.75 °C/W, and verified 55 V V_CEO rating for high-voltage RF amplifier stages.

Technical Context

The SD1727 operates as a silicon epitaxial planar NPN device with emitter ballasting to sustain extreme VSWR and load mismatch stress in HF linear amplifiers. Its static h_FE range (18–43.5) supports stable biasing across production lots at I_CQ = 100 mA.

Dynamic characterization confirms 14 dB small-signal gain and 37% collector efficiency at 30 MHz, 50 V V_CE, and 150 W PEP output-meeting MIL-STD-883 Class AB linearity requirements for amateur and marine SSB transceivers.

Key Specifications

Pinout & Package

SD1727 uses the M164 4-lead epoxy-sealed flange package with isolated collector tab. The metal case serves as the collector terminal, and leads are arranged in linear order: Pin 1 = Collector (case), Pin 2 = Emitter, Pin 3 = Base, Pin 4 = Emitter (dual emitter connection).

Key Features

Applications

Availability

SD1727 is available at Aetrix Electronics and suitable for HF amateur radio transceivers, marine SSB communications systems, and fixed-station HF amplifiers requiring stable component supply despite its obsolete status.

Supply support for SD1727 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 SD1727 belongs to ST's legacy RF power transistor product line, engineered specifically for high-linearity, high-ruggedness HF SSB amplifier applications in demanding environmental conditions.

FAQ

Is SD1727 still in active production?

No. The SD1727 is marked "Obsolete Product(s)" in ST's official documentation (Rev. 2, June 2004). It is no longer manufactured, but Aetrix Electronics maintains limited legacy stock with full traceability and test validation per original specification.

Can SD1727 operate in Class A mode?

Yes. Per footnote in the datasheet, SD1727 is usable in Class A at 40 V supply, delivering 30 W PEP with 14 dB gain and –40 dBc IMD. This configuration reduces thermal stress but sacrifices output power and efficiency compared to Class AB.

What is the significance of dual emitter terminals (Pins 2 and 4)?

Pins 2 and 4 are electrically identical emitter connections. Their dual layout reduces total emitter lead inductance by ~40%, improving high-frequency stability and IMD performance at 30 MHz-critical for SSB linearity compliance.

Does SD1727 require external base-emitter protection diodes?

No. The device incorporates internal emitter-base protection via integrated ballast resistors and process-level junction design. External clamping diodes are unnecessary unless operating outside absolute max ratings (e.g., >4 V V_EBO).