Analog Devices Inc. 115857-HMC634LC4

Overview

HMC634LC4 from Analog Devices (formerly Hittite Microwave) is a GaAs PHEMT MMIC driver amplifier operating from 5 to 20 GHz, delivering 21 dB small-signal gain, +22 dBm P1dB output power, and +29 dBm OIP3 while drawing 180 mA from a +5 V supply. It is DC-coupled at bias pins and features 50 Ω matched RF input/output ports with no external matching required - ideal for microwave radio LO driver stages.

For engineers reviewing the HMC634LC4 datasheet, HMC634LC4 pinout, HMC634LC4 application, or HMC634LC4 equivalent, this broadband GaAs amplifier supports critical design tasks including gain staging in point-to-point radios, mixer LO drive, and high-linearity signal conditioning across 5–20 GHz with stable thermal performance and MSL3-compliant 4×4 mm ceramic SMT packaging.

Technical Context

The HMC634LC4 employs a monolithic GaAs PHEMT process with four independent drain supply pins (Vdd1–Vdd4) and a single gate bias pin (Vgg) enabling precise current control via adjustable negative gate voltage (−2 to 0 V). Its I/Os are internally AC-coupled and 50 Ω matched, eliminating external DC blocking or impedance-matching components.

Thermal management is supported by an exposed ground paddle and alumina package with 89.46 °C/W channel-to-package thermal resistance; operation is specified from −40 °C to +85 °C with 175 °C maximum channel temperature. Gain variation is tightly controlled at ≤0.035 dB/°C across temperature.

Key Specifications

Pinout & Package

Package: 24-lead, 4 × 4 mm ceramic surface-mount package with exposed ground paddle; alumina body, gold-over-nickel plating; MSL Level 3 (260 °C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar driver amplifier applications.

Compared with HMC634LC4, HMC635LC4 extends usable bandwidth upward but sacrifices 1 dB of P1dB and 2 dB of OIP3; QPL9547 offers superior efficiency and linearity below 6 GHz but is unusable above that threshold - making HMC634LC4 uniquely balanced for 5–20 GHz driver needs.

Availability

HMC634LC4 is available at Aetrix Electronics and suitable for point-to-point radios, LO driver circuits, and military communications systems requiring stable component supply, consistent RF performance, and long-term obsolescence management.

Supply support for HMC634LC4 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-frequency RF/Microwave portfolio into ADI's broader signal chain solutions.

The HMC634LC4 belongs to Hittite's GaAs PHEMT MMIC driver amplifier product line, designed specifically for broadband microwave radio, test instrumentation, and defense electronics requiring high gain, linearity, and thermal stability.

FAQ

What is the recommended gate bias voltage range for the HMC634LC4?

The HMC634LC4 requires a gate bias voltage (Vgg) between −2 V and 0 V DC to achieve the specified 180 mA supply current. Adjusting Vgg within this range allows fine-tuning of quiescent current and trade-offs between gain, output power, and PAE. The HMC634LC4 datasheet specifies that −0.76 V is typical for nominal operation, and external decoupling is mandatory per the "MMIC Amplifier Biasing Procedure" application note.

Does the HMC634LC4 require external matching components at RF ports?

No, the HMC634LC4 features internally matched 50 Ω input and output ports with integrated DC blocking - no external matching networks, baluns, or DC blocking capacitors are needed in the RF signal path. This simplifies layout and improves repeatability across production units, though external bypassing on Vdd and Vgg pins remains mandatory per the application circuit.

What is the thermal resistance and maximum channel temperature for the HMC634LC4?

The HMC634LC4 has a channel-to-package thermal resistance (θ_CH-PK) of 89.46 °C/W and a maximum allowable channel temperature of 175 °C. At 85 °C ambient, it supports up to 1 W continuous power dissipation (derated above 85 °C at 11.17 mW/°C). Proper grounding of the exposed paddle and use of thermal vias are essential to maintain safe junction temperatures in the HMC634LC4.

Can the HMC634LC4 operate outside the 5–20 GHz range?

The HMC634LC4 is characterized and guaranteed for operation from 5 to 20 GHz. While some gain may be observed below 5 GHz or above 20 GHz, performance parameters such as gain flatness, return loss, and OIP3 are not specified or warranted outside this band. For reliable design, the HMC634LC4 should be used strictly within its rated 5–20 GHz frequency range.

What is the moisture sensitivity level (MSL) rating for the HMC634LC4 package?

The HMC634LC4 is rated MSL Level 3 per JEDEC J-STD-020, with a floor life of 168 hours at ≤30 °C/60% RH. The maximum peak reflow temperature is 260 °C. Prior to reflow, baking per J-STD-033 is required if floor life is exceeded. This MSL3 rating confirms compatibility with standard automated SMT assembly processes used for the HMC634LC4.