Analog Devices Inc. 124390-HMC740ST89E

Overview

HMC740ST89E from Analog Devices (formerly Hittite Microwave) is an InGaP HBT MMIC gain block amplifier operating from 0.05 to 3 GHz, delivering +18 dBm P1dB output power, 15 dB small-signal gain, and +40 dBm output IP3 at 100 MHz - ideal as a cascadable 50 Ω RF/IF driver or LO amplifier in broadband wireless infrastructure.

For engineers reviewing the HMC740ST89E datasheet, HMC740ST89E pinout, HMC740ST89E application, or HMC740ST89E equivalent, key selection criteria include its active bias network enabling stable current over temperature, single +5 V supply operation, SOT89 package compatibility with RF layout best practices, and robust Class 1C ESD protection.

Technical Context

The HMC740ST89E integrates an InGaP HBT process with on-die active bias circuitry to maintain stable quiescent current (88 mA) across –40°C to +85°C, eliminating external bias adjustment components. Its 50 Ω matched input/output enables direct cascade without matching networks.

It achieves broadband performance via monolithic design: gain flatness ±0.7 dB from 0.05–3 GHz, input/output return loss ≥15 dB, reverse isolation ≥20 dB, and noise figure of 3.5 dB - all specified at +5 V, 25°C.

Key Specifications

Pinout & Package

Package: Industry-standard SOT89 (RoHS-compliant, MSL1, matte Sn plating), with exposed thermal pad requiring solder connection to PCB ground plane for thermal management and RF grounding.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC441LP3E and QPL9057, the HMC740ST89E uniquely balances ultra-low external component count (single +5 V, no bias resistors), full 0.05–3 GHz coverage, and +40 dBm IP3 - making it optimal for cost-sensitive, thermally stable, and layout-simple RF gain stages in infrastructure equipment.

Availability

HMC740ST89E is available at Aetrix Electronics and suitable for cellular base stations, WiMAX/WLAN access points, and CATV infrastructure requiring stable component supply, consistent RF performance, and long-term production continuity.

Supply support for HMC740ST89E 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 continues its high-frequency RF IC portfolio, specializing in mmWave, microwave, and broadband solutions for communications and defense.

The HMC740ST89E belongs to Hittite's legacy MMIC gain block family, designed specifically for cascadable, low-component-count RF/IF amplification in wireless infrastructure and test equipment.

FAQ

What is the recommended DC blocking capacitor value for the HMC740ST89E input?

A 470 pF capacitor in 0402 package is used on the official evaluation PCB (P/N 119392) for the HMC740ST89E input. This value provides effective DC blocking down to 0.05 GHz while maintaining low insertion loss and phase shift across the full 0.05–3 GHz band. Larger values may improve low-frequency coupling but risk degrading high-frequency return loss.

Does the HMC740ST89E require external bias resistors?

No - the HMC740ST89E incorporates an integrated active bias network that fixes quiescent current at 88 mA across temperature and supply voltage variations. No external bias resistors, potentiometers, or temperature-sensing components are needed, simplifying layout and improving reliability in production systems.

Can the HMC740ST89E operate from a supply voltage other than +5 V?

The HMC740ST89E is characterized and rated for +5 V operation, with absolute maximum Vcc of +5.5 V. Performance metrics (gain, P1dB, IP3) degrade below 4.5 V and above 5.5 V. While functional at 4.5–5.5 V per datasheet curves, +5 V is the design center and recommended for guaranteed specification compliance.

How should the SOT89 thermal pad of the HMC740ST89E be connected?

The SOT89 package bottom and pins 2 and 4 of the HMC740ST89E must be soldered directly to a solid PCB ground plane. Use ≥6 thermal vias (0.3 mm diameter) under the pad, filled or capped, connecting to inner/ground layers. This ensures thermal resistance remains near the specified 97.78 °C/W and maintains RF grounding integrity for return loss and isolation specs.

Is the HMC740ST89E pin-compatible with other SOT89 RF amplifiers?

No documented pin-compatible alternatives exist for the HMC740ST89E. Its pin 3 serves dual function as RF output and Vcc feed, unlike standard SOT89 amplifiers with separate Vcc and RFOUT pins. Substitution requires schematic and layout revision - always verify pin functions against the official HMC740ST89E pinout before replacement.