Analog Devices Inc. 124390-HMC741ST89E

Overview

HMC741ST89E from Analog Devices (formerly Hittite Microwave) is an InGaP HBT MMIC gain block amplifier operating from 50 MHz to 3 GHz, delivering 20 dB small-signal gain, +18.5 dBm P1dB output power, and +42 dBm OIP3 at 200 MHz - ideal as a cascadable 50 Ω RF/IF driver or LO amplifier in wireless infrastructure.

For engineers reviewing the HMC741ST89E datasheet, HMC741ST89E pinout, HMC741ST89E application, or HMC741ST89E equivalent, key selection criteria include its active bias network enabling stable current over temperature, SOT89 package compatibility with standard RF layout practices, robust Class 1C ESD rating, and single +5 V supply operation without external biasing components.

Technical Context

The HMC741ST89E integrates an InGaP HBT process with on-die active bias circuitry, eliminating need for external base bias resistors and ensuring stable quiescent current (96 mA typical) across −40°C to +85°C. Its 50 Ω matched input/output enables direct cascading without matching networks.

It delivers broadband performance with ±0.3 dB gain flatness from 150–240 MHz and maintains >16 dB input return loss and >17 dB output return loss across 50–3000 MHz. Reverse isolation exceeds 25 dB, minimizing stage interaction in multi-amplifier chains.

Key Specifications

Pinout & Package

Package: Industry-standard SOT-89 (3-lead, molded plastic, RoHS-compliant, MSL1, matte Sn plating). Thermal resistance θ_JL = 97.83 °C/W; requires soldering of all ground leads and exposed package bottom to PCB RF ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with QPL9057 and HMC441LC3B, the HMC741ST89E uniquely combines single-supply operation, integrated active bias, and guaranteed 50–3000 MHz performance in a low-cost SOT-89 package - making it optimal for production-grade wireless infrastructure where thermal stability and layout simplicity are critical.

Availability

HMC741ST89E is available at Aetrix Electronics and suitable for cellular infrastructure, fixed wireless access, and test equipment requiring stable component supply, consistent RF performance, and long-term manufacturability.

Supply support for HMC741ST89E 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, integrating its high-performance RF/microwave portfolio into ADI's broader signal chain solutions.

The HMC741ST89E belongs to Hittite's legacy MMIC gain block family, designed specifically for broadband, cascadable RF/IF amplification in wireless infrastructure and instrumentation where reliability, linearity, and ease of integration are essential.

FAQ

What is the recommended DC blocking capacitor value for the HMC741ST89E input?

A 470 pF capacitor in 0402 package is specified in the official evaluation board design (PCB 119392) for the HMC741ST89E input. This value provides effective DC blocking while maintaining low reactance (<1 Ω) across the full 50 MHz–3 GHz band, preserving input return loss and gain flatness. The HMC741ST89E input is DC-coupled, so omission of this capacitor risks damage from external DC offset.

Does the HMC741ST89E require external bias resistors?

No - the HMC741ST89E incorporates an on-die active bias network that regulates collector current to 96 mA over temperature and supply voltage variations. Unlike discrete transistor or older MMIC amplifiers, it operates directly from a +5 V supply applied to Pin 3 (OUT) with no external resistors needed for biasing, reducing BOM count and layout complexity.

What is the maximum RF input power the HMC741ST89E can tolerate without damage?

The absolute maximum RF input power for the HMC741ST89E is +15 dBm, as specified in the Absolute Maximum Ratings table. Exceeding this level risks permanent degradation of the InGaP HBT junction, especially under continuous-wave conditions. For reliable operation, input power should remain ≤0 dBm in linear applications and ≤+10 dBm in compression-limited use cases.

How does the HMC741ST89E perform at elevated temperatures?

The HMC741ST89E exhibits exceptional thermal stability: gain variation is only 0.004 dB/°C, and output IP3 remains ≥40.5 dBm from −40°C to +85°C. At +85°C, P1dB drops by ≤0.5 dB versus +25°C, and quiescent current stays within ±3% of 96 mA - confirming its suitability for uncooled outdoor wireless equipment and industrial test gear.

Is the HMC741ST89E pin-compatible with other SOT-89 RF amplifiers?

No documented pin-compatible alternatives exist for the HMC741ST89E. Its Pin 3 serves dual function as RF output and Vcc feed, unlike conventional SOT-89 amplifiers where Vcc is separate. Substituting another SOT-89 part risks incorrect biasing or RF path disruption. Always verify pin function mapping using the official HMC741ST89E pinout before board reuse.