Analog Devices Inc. 105406-HMC424LP3

Overview

HMC424LP3 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC 6-bit digital attenuator IC used for precision RF signal level control in high-frequency front-ends. It delivers 0.5 dB LSB steps across 31.5 dB range, ±0.5 dB typical bit error, <4 dB insertion loss up to 13 GHz, and +32 dBm IIP3 - ideal for microwave radio transmit/receive chains requiring stable attenuation under wideband operation.

For engineers reviewing the HMC424LP3 datasheet, HMC424LP3 pinout, HMC424LP3 application, or HMC424LP3 equivalent, key selection criteria include DC–13 GHz bandwidth, -5 V single-supply biasing, 6-bit parallel TTL-compatible control interface, and leadless 9 mm² SMT package with exposed paddle for RF grounding.

Technical Context

The HMC424LP3 implements a broadband GaAs MMIC architecture with six independent digitally controlled attenuation bits (0.5/1/2/4/8/16 dB), each driven by a dedicated 0/–5 V logic input. Its monolithic design enables DC-coupled 50 Ω RF ports and supports continuous operation from baseband to Ka-band without external bias tees.

It uses a single –5 V Vee supply referenced to ground, with control inputs drawing only 5 µA (high) or 35 µA (low). Switching speed is 30 ns rise/fall and 50 ns ON/OFF delay, enabling fast AGC and TDD-based power management in instrumentation and radar systems.

Key Specifications

Pinout & Package

Package: 16-lead 3×3 mm leadless plastic QFN (9 mm²) with exposed metal paddle requiring solder connection to PCB RF ground per Hittite land pattern guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC424LP3E and QM11036, the HMC424LP3 offers identical RF performance to its RoHS sibling but with Sn/Pb finish for legacy reflow, while differing from QM11036 in control voltage polarity, IIP3, and reflow compatibility - making it optimal for high-linearity, negative-supply RF subsystems.

Availability

HMC424LP3 is available at Aetrix Electronics and suitable for 5G infrastructure, fiber-optic line cards, and microwave radio applications requiring stable component supply, long-term obsolescence planning, and traceable sourcing from authorized channels.

Supply support for HMC424LP3 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 ADI's broader signal chain solutions, emphasizing performance, reliability, and application-specific integration.

The HMC424LP3 belongs to Hittite's legacy GaAs MMIC digital attenuator product line, designed specifically for broadband wireless infrastructure, test instrumentation, and defense electronics demanding wideband linearity and precision attenuation.

FAQ

What is the operating temperature range for the HMC424LP3?

The HMC424LP3 operates from –55 °C to +85 °C. This extended industrial temperature range ensures reliable performance in outdoor base station enclosures and airborne communication systems. The device's thermal resistance of 330 °C/W and exposed paddle design support stable operation at maximum ambient temperature when properly mounted to a thermally optimized PCB. All electrical specifications in the datasheet are guaranteed across this full range.

Does the HMC424LP3 require external DC blocking capacitors on its RF ports?

Yes, the HMC424LP3 features DC-coupled RF ports (pins 2 and 11), so external blocking capacitors are required if the RF line has non-zero DC potential. These capacitors must be selected for low series inductance and sufficient voltage rating to avoid degrading insertion loss or return loss above 10 GHz. The evaluation board (105406) uses 0.01 µF 0603 capacitors, and Hittite recommends matching impedance to 50 Ω across the operating band.

Can the HMC424LP3 be used with positive control logic voltages?

No - the HMC424LP3 requires negative control logic: "low" = 0 to –3 V, "high" = Vee to Vee+0.8 V (i.e., –5 V to –4.2 V). It is incompatible with standard 0/3.3 V or 0/5 V CMOS/TTL logic without level-shifting circuitry. The datasheet specifies driver circuits using inverters and resistors to translate positive logic into compliant –5 V swing signals, and improper voltage levels risk incorrect attenuation states or damage.

What is the maximum RF input power the HMC424LP3 can handle?

The HMC424LP3 supports +25 dBm absolute maximum RF input power (0.5–13 GHz), but its linear operating limit is defined by P1dB (+22 dBm typical) and IIP3 (+32 dBm). For sustained operation, Analog Devices recommends staying below +20 dBm to ensure long-term reliability and maintain specified bit error and return loss. Exceeding +22 dBm risks compression and degraded adjacent-channel power ratio in sensitive receiver paths.

Is the HMC424LP3 pin-compatible with the HMC424LP3E?

Yes - the HMC424LP3 and HMC424LP3E share identical pinout, package dimensions, electrical specifications, and thermal characteristics. The only differences are RoHS compliance (matte Sn vs. Sn/Pb finish), MSL rating (both MSL1), and peak reflow temperature (260 °C vs. 235 °C). No PCB layout changes are needed when migrating between them, though solder paste profile must be adjusted for the higher reflow temperature of the HMC424LP3E.