Analog Devices Inc. HMC424LH5

Overview

HMC424LH5 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC 6-bit digital attenuator in a hermetic SMT package, delivering 0.5 dB LSB steps across DC–13 GHz with ≤3.2 dB typical insertion loss at 4 GHz, ±0.4 dB typical attenuation accuracy, and +32 dBm IIP3 - deployed in military radar front-ends requiring precise RF gain control.

For engineers reviewing the HMC424LH5 datasheet, HMC424LH5 pinout, HMC424LH5 application, or HMC424LH5 equivalent, key selection criteria include DC–13 GHz bandwidth, -5 V single-supply biasing, 6-bit parallel TTL-compatible control, MIL-PRF-38535 screening availability, and hermetic ceramic packaging for space-grade reliability.

Technical Context

The HMC424LH5 implements a broadband GaAs MMIC architecture with six independent bit-controlled FET-based attenuation cells, each toggled via 0/–5 V logic levels on dedicated V1–V6 inputs. Its DC-coupled 50 Ω RF path supports baseband-to-RF signal conditioning without external blocking capacitors when DC bias permits.

Operation relies on a single –5 V Vee supply (±10%) enabling true DC operation; all six control lines accept standard logic thresholds with low quiescent current (35 µA per low-state input). Bit error remains ≤±0.3 dB typical across frequency and attenuation states due to matched cell design and on-chip termination.

Key Specifications

Pinout & Package

Hermetic leadless ceramic package (25 mm²), 12-pad outline with exposed ground paddle; RoHS-compliant and compatible with lead-free reflow.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital RF attenuator applications.

Compared with HMC424LH5, HMC624LP4E offers identical RF specs but sacrifices hermetic reliability for lower cost and smaller footprint, while PE43711 trades bandwidth and DC coupling for silicon integration benefits - making HMC424LH5 the sole choice for DC–13 GHz, space-qualified, single-negative-rail applications.

Availability

HMC424LH5 is available at Aetrix Electronics and suitable for telecom infrastructure, military radar, space systems, and test instrumentation requiring stable component supply with guaranteed long-term availability and controlled obsolescence management.

Supply support for HMC424LH5 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 maintains its high-frequency RF product portfolio, specializing in GaAs, GaN, and SiGe MMIC solutions for defense, aerospace, and communications.

The HMC424LH5 belongs to Hittite's legacy high-reliability MMIC attenuator family, engineered specifically for DC–13 GHz precision RF gain control in mission-critical electronic warfare, radar, and satellite communication systems.

FAQ

What is the absolute maximum RF input power rating for the HMC424LH5?

The HMC424LH5 has an absolute maximum RF input power rating of +25 dBm across 0.5–13 GHz, as specified in the Absolute Maximum Ratings table. Exceeding this level risks permanent damage to the GaAs FET cells. For reliable continuous operation, the datasheet recommends limiting input power to +22 dBm (0.1 dB compression point) to maintain linearity and avoid distortion in the HMC424LH5 signal path.

Does the HMC424LH5 require external DC blocking capacitors on its RF ports?

The HMC424LH5 features DC-coupled RF1 and RF2 ports, so external DC blocking capacitors are only required if the connected circuitry imposes a DC voltage offset incompatible with the HMC424LH5's 0 V nominal RF common-mode voltage. When interfacing with AC-coupled stages or biased amplifiers, 100 pF NP0 capacitors placed within 2 mm of the HMC424LH5 pads preserve impedance match and prevent latch-up.

Can the HMC424LH5 operate with control voltages referenced to ground instead of Vee?

No - the HMC424LH5 control inputs V1–V6 are designed for negative logic: "Low" = 0 V, "High" = Vee (–5 V). Driving them with ground-referenced logic (e.g., 0/+3.3 V) violates the absolute maximum rating and may cause latch-up or degraded bit error. The HMC424LH5 requires a level-shifting interface or negative-voltage logic drivers to ensure proper V1–V6 voltage compliance.

Is the HMC424LH5 pin-compatible with any other Hittite or Analog Devices attenuators?

The HMC424LH5 has a unique 12-pad hermetic ceramic footprint and is not pin-compatible with other Hittite or Analog Devices digital attenuators such as the HMC624LP4E (16-pin QFN) or ADL5240 (16-pin LFCSP). Its pinout, pad layout, and grounding scheme are specific to the LH5 package; PCB redesign is required for substitution.

What thermal management is required for the HMC424LH5 at maximum RF power?

The HMC424LH5 has a thermal resistance of 344 °C/W and a maximum continuous power dissipation of 0.18 W at 85 °C ambient. To sustain +22 dBm input power reliably, the PCB must provide low-thermal-resistance grounding: the exposed paddle and all GND pads (pins 8, 10, 12) must be soldered to a solid internal ground plane with ≥6 thermal vias (0.3 mm diameter) connecting to additional ground layers - ensuring junction temperature stays below 125 °C in the HMC424LH5.