Analog Devices Inc. 125682-HMC789ST89E

Overview

HMC789ST89E from Analog Devices (formerly Hittite Microwave) is a GaAs InGaP HBT gain block MMIC amplifier operating from 0.7 to 2.8 GHz, delivering 18 dB typical gain, +25 dBm P1dB output power, and +42 dBm output IP3 at +5 V supply. It serves as a high-linearity RF driver or pre-driver in cellular/4G base station transmit chains and fixed wireless infrastructure.

For engineers reviewing the HMC789ST89E datasheet, HMC789ST89E pinout, HMC789ST89E application, or HMC789ST89E equivalent, key selection criteria include its SOT89 package compatibility, single +5 V bias requirement, broadband 0.7–2.8 GHz operation, and verified performance across 900 MHz, 1900 MHz, and 2600 MHz bands for PA driver staging.

Technical Context

The HMC789ST89E employs a monolithic GaAs InGaP HBT process optimized for high linearity and thermal stability across -40°C to +85°C. Its DC-coupled RFIN and RFOUT pins require external matching networks-distinct per band (e.g., 900 MHz uses L1=18 nH, C7=1.2 pF; 2600 MHz uses L2=12 nH, C7=0.3 pF).

Performance is specified across three discrete frequency bands: 810–960 MHz, 1710–1990 MHz, and 2420–2700 MHz-with consistent +42 dBm OIP3, 3.8 dB noise figure, and 45% PAE at +25 dBm Pout. Gain variation is tightly controlled at ±0.01 dB/°C.

Key Specifications

Pinout & Package

Package: SOT89 with exposed ground paddle; RoHS-compliant low-stress plastic body; MSL1 rating; 100% matte tin lead finish; thermal resistance θ_JA = 77 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF gain block applications.

Compared with QPL9547 and PSA-2-50+, the HMC789ST89E provides optimal trade-off of 0.7–2.8 GHz coverage, +42 dBm linearity, and SOT89 manufacturability-making it preferred for cost-sensitive, thermally constrained cellular and fixed wireless designs requiring proven field reliability.

Availability

HMC789ST89E is available at Aetrix Electronics and suitable for cellular infrastructure, fixed wireless access units, and RF test equipment requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for HMC789ST89E 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

Analog Devices acquired Hittite Microwave in 2014 and integrates its high-frequency RF portfolio into precision analog and RF solutions for communications, defense, and instrumentation markets.

The HMC789ST89E belongs to Hittite's legacy GaAs gain block family, engineered specifically for high-efficiency, high-linearity RF driver applications in cellular, microwave radio, and broadband infrastructure.

FAQ

What is the recommended DC bias configuration for HMC789ST89E?

The HMC789ST89E operates from a single +5 V supply applied to Pin 3 (RFOUT), which serves as both RF output and DC bias input. No external bias network is needed beyond standard decoupling capacitors (C4=1000 pF, C5=2.2 µF). The device draws 125–150 mA quiescent current, and thermal management via the exposed paddle is critical for sustained +25 dBm operation. HMC789ST89E requires no gate/base voltage adjustment-bias is internally set.

Does HMC789ST89E support DC-coupled operation?

Yes, HMC789ST89E features DC-coupled RFIN (Pin 1) and RFOUT (Pin 3), enabling seamless integration into IF or baseband-coupled architectures. External matching components must be selected to maintain DC continuity while providing impedance transformation-e.g., 18 nH inductor in series with RFIN and shunt capacitor to ground at 900 MHz. HMC789ST89E does not require AC coupling unless system-level isolation mandates it.

What is the maximum RF input power rating for HMC789ST89E?

The absolute maximum RF input power for HMC789ST89E is +18 dBm at +5 V supply, per its Absolute Maximum Ratings table. Exceeding this risks permanent damage to the InGaP HBT transistor. For reliable operation, input drive should remain ≤ +10 dBm in linear mode-verified in two-tone IP3 tests. HMC789ST89E exhibits graceful compression onset, but sustained overdrive degrades long-term reliability.

How does HMC789ST89E perform across temperature?

HMC789ST89E maintains stable RF performance from -40°C to +85°C: gain variation is ≤ ±0.01 dB/°C, OIP3 varies by <1 dB, and P1dB shifts <0.5 dB across temperature. At +85°C, output power remains within 0.3 dB of room-temperature values due to integrated thermal compensation. This stability is validated in all three bands (900/1900/2600 MHz) and makes HMC789ST89E suitable for uncooled outdoor wireless units.

Is HMC789ST89E pin-compatible with other SOT89 RF amplifiers?

No documented pin-compatible alternatives exist for HMC789ST89E. While other SOT89 amplifiers share the same footprint, their pin functions differ-e.g., some assign Pin 1 to Vcc or GND instead of RFIN. HMC789ST89E's unique RFIN–GND–RFOUT–GND pinout (1–2–3–4) requires dedicated PCB layout. Substitution would necessitate redesign of matching networks and bias routing, even if mechanical fit is achieved.