Analog Devices Inc. HMC425LP3ETR

Overview

HMC425LP3ETR from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC 6-bit digital positive-control RF attenuator operating from 2.2 to 8.0 GHz, delivering 0.5 dB LSB steps up to 31.5 dB total attenuation, ±0.5 dB typical bit error, and 3.8 dB typical insertion loss at 6–8 GHz - deployed in microwave radio, VSAT, and broadband telecom front-ends.

For engineers reviewing the HMC425LP3ETR datasheet, HMC425LP3ETR pinout, HMC425LP3ETR application, or HMC425LP3ETR equivalent, key selection criteria include frequency coverage (2.2–8.0 GHz), 6-bit parallel control interface, +5 V single-supply operation, 3×3 mm QFN package with exposed paddle, and IIP3 of +40 dBm at mid-attenuation states.

Technical Context

The HMC425LP3ETR implements a monolithic GaAs MMIC architecture with six independent CMOS-compatible control inputs (V1–V6), each toggling between 0 V and +3 to +5 V to select discrete attenuation bits (0.5, 1, 2, 4, 8, 16 dB). It requires no external biasing beyond Vdd and uses DC-coupled 50 Ω RF ports (RFIN/RFOUT) with mandatory blocking capacitors.

Its RF performance is characterized across –40 °C to +85 °C, with worst-case step error bounded by ±0.5 dB + 5% of setting, return loss ≥15 dB over full band, and switching times of 160 ns (tRISE/tFALL) and 180 ns (tON/tOFF), enabling fast AGC and channel calibration in time-sensitive systems.

Key Specifications

Pinout & Package

Package: 16-lead 3×3 mm leadless plastic QFN (MSL1), with exposed metal paddle requiring solder connection to PCB RF ground per Hittite Application Note land pattern guidance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC425LP3ETR, HMC425LP3E offers identical RF performance with RoHS compliance, while QM11036 trades linearity and control interface simplicity for finer attenuation granularity - making HMC425LP3ETR optimal for cost-sensitive, high-linearity microwave systems requiring industry-standard 5 V logic control.

Availability

HMC425LP3ETR is available at Aetrix Electronics and suitable for microwave radio, VSAT outdoor units, and fiber-optic transceiver calibration requiring stable component supply, long-term obsolescence management, and traceable lot-level sourcing.

Supply support for HMC425LP3ETR 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 IC portfolio into precision RF signal chain solutions for defense, communications, and instrumentation markets.

The HMC425LP3ETR belongs to Hittite's broadband GaAs MMIC digital attenuator product line, engineered for high-linearity, low-error RF gain control in 2–8 GHz infrastructure and military systems.

FAQ

What is the operating temperature range for the HMC425LP3ETR?

The HMC425LP3ETR is rated for continuous operation from –40 °C to +85 °C ambient temperature. Its RF specifications - including insertion loss, attenuation accuracy, and IIP3 - are guaranteed across this full industrial temperature range, with characterization data provided at +25 °C, –40 °C, and +85 °C in the official datasheet. Thermal performance is enhanced by the exposed paddle, which must be soldered to the PCB ground plane.

Does the HMC425LP3ETR require external DC blocking capacitors on its RF ports?

Yes, the HMC425LP3ETR features DC-coupled RFIN and RFOUT pins matched to 50 Ω, and external DC blocking capacitors are mandatory to prevent DC voltage injection into connected components such as LNAs or PAs. The evaluation board uses 100 pF capacitors (C2, C3), and layout guidelines specify placement adjacent to the package for minimal series inductance.

What is the maximum RF input power the HMC425LP3ETR can handle at +5 V supply?

At Vdd = +5 V, the HMC425LP3ETR supports +22 dBm input power for 0.1 dB compression across 2.2–8.0 GHz. Absolute maximum RF input power is rated at +30 dBm, but operation above +22 dBm risks compression and degraded linearity. For reliable linear operation, keep input power ≤ +22 dBm when using +5 V bias.

Is the HMC425LP3ETR pin-compatible with the HMC425LP3E?

Yes, the HMC425LP3ETR and HMC425LP3E share identical pinout, package dimensions (3×3 mm QFN), and electrical functionality. The sole difference is lead finish: HMC425LP3ETR uses Sn/Pb, while HMC425LP3E uses 100% matte Sn for RoHS compliance. Both have MSL1 rating and require no PCB layout changes for substitution.

How is attenuation state selected on the HMC425LP3ETR?

Attenuation state is selected via six parallel control inputs (V1–V6), each accepting 0 V (low) or +3 to +5 V (high) logic levels. The truth table defines bit weights: V6 = 0.5 dB (LSB), V5 = 1 dB, V4 = 2 dB, V3 = 4 dB, V2 = 8 dB, V1 = 16 dB. Any combination yields sum-of-enabled-bits attenuation - e.g., high on V1, V3, and V6 gives 16 + 4 + 0.5 = 20.5 dB.