ADI PDN 25_0079: GCS P1HBT RF Amplifiers Discontinued, Last-Time-Buy Closed

What changed #

Analog Devices published Product Discontinuance Notice PDN 25_0079 on 29 September 2025, announcing the obsolescence of the GCS P1HBT process — the GaAs HBT fabrication process behind a long list of Hittite/ADI RF amplifier and related parts. The notice is real and dated, and the key dates are now material to any buyer with these parts on an active bill of materials:

The stated reason is external: ADI's foundry partner Global Communication Semiconductors (GCS) decided to end-of-life the P1HBT process, and ADI says it could not secure a replacement. The discontinued families include HMC311, HMC313, HMC326, HMC327, HMC395–HMC415, HMC450 and HMC452, among others — a broad set of RF gain blocks, drivers and amplifier die used across wireless infrastructure, test equipment and microwave/communications front ends.

Why buyers should care #

The practical consequence is simple: the authorized ordering window for these parts is effectively over. Any new requirement now has to be filled by one of two routes, neither of which is the normal franchise channel:

• LTS backlog — orders that were placed before the 7 May 2026 LTB and will ship on or before 26 March 2027. If you did not place an LTB, this route is closed to you.
• Independent / authorized-resale market — the open market for parts that have left the franchise pipeline.

That second route is exactly where risk concentrates. Parts that go EOL with a closed LTB are the ones most likely to surface as reclaimed, remarked or counterfeit units in independent channels, especially when the original package and date code still look plausible. ADI's own notice lists recommended alternates for some lines (for example HMC311ALP3E for the HMC311 family) but marks many as "See Comments" with a different replacement part, and explicitly states pin-to-pin compatibility as "No" for several. Treating an ADI-suggested alternate as a drop-in without engineering verification is a mistake — package, gain, bias and footprint can all differ.

Affected component areas #

• RF / microwave amplifiers — the HMC3xx and HMC4xx gain-block and driver families.
• Wireless infrastructure, test & measurement, radar and comms front ends — designs where these amplifiers sit on the receive or transmit chain.
• Long-lifecycle programs — industrial, medical, aerospace and defense equipment that was qualified on a P1HBT part and now must plan around a fixed LTS date.

RFQ and sourcing checks #

Practical takeaway #

If any of these HMC RF amplifiers are on a current BOM, the action is not "wait and see" — the LTB has already passed. Scrub the BOM against PDN 25_0079, confirm how much authorized backlog (if any) ships before 26 March 2027, and decide between securing independent stock with full test and traceability or qualifying an ADI-listed alternate with engineering sign-off. For new designs, do not start on a P1HBT part at all. Any RFQ on these lines should state the exact MPN, package, acceptable date-code window and intended use so the response reflects real availability rather than a stale franchise price.