Analog Devices Inc. 131552-HMC973LP3E

Overview

HMC973LP3E from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC voltage-variable attenuator (VVA) operating from 0.5 to 6.0 GHz, featuring 26 dB attenuation range, +35 dBm input IP3, absorptive topology, and single 0–5 V analog control. It serves as a unidirectional RF signal level controller in microwave transceivers and infrastructure equipment.

For engineers reviewing the HMC973LP3E datasheet, HMC973LP3E pinout, HMC973LP3E application, or HMC973LP3E equivalent, key selection criteria include its 0.5–6.0 GHz bandwidth, 3.5–5.0 dB insertion loss (0.5–4.0 GHz), RoHS-compliant 3×3 mm QFN package, and DC-coupled 50 Ω RFIN/RFOUT interfaces with required blocking capacitors.

Technical Context

The HMC973LP3E implements a shunt-type GaAs FET-based attenuator architecture controlled by an analog voltage (Vctrl) applied to Pin 7. Its absorptive design ensures stable impedance matching across the full 26 dB attenuation range without reflective signal degradation.

Optimum linearity (+35 dBm IP3) is achieved only when RF input is applied to Pin 10 (RFIN); RF output is extracted from Pin 3 (RFOUT). The device draws just 200–300 µA supply current at Vdd = +5 V and operates over –40 °C to +85 °C.

Key Specifications

Pinout & Package

Package: 16-lead, 3×3 mm RoHS-compliant QFN with exposed ground paddle; requires soldering all ground leads (Pins 1, 2, 4, 9, 11, 12) and paddle to PCB RF ground per Hittite land pattern guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage-variable attenuator applications.

Compared with HMC973LP3E, HMC1085LP3E trades 3 dB IP3 for broader bandwidth and deeper attenuation, while QM11036 delivers higher linearity at the cost of non-compatible control architecture and layout changes.

Availability

HMC973LP3E is available at Aetrix Electronics and suitable for point-to-point radio, cellular/4G infrastructure, and military radar applications requiring stable component supply, consistent RF performance, and long-term obsolescence mitigation.

Supply support for HMC973LP3E 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 and SiGe MMIC solutions for defense, communications, and instrumentation markets.

The HMC973LP3E belongs to Hittite's legacy voltage-variable attenuator family, designed specifically for analog-controlled RF power management in microwave infrastructure where linearity, bandwidth, and compact packaging are critical.

FAQ

What is the recommended PCB grounding strategy for the HMC973LP3E?

Per the datasheet, all ground pins (1, 2, 4, 9, 11, 12) and the exposed ground paddle must be soldered directly to the PCB RF ground plane using multiple thermal vias. This ensures optimal RF return path integrity, thermal dissipation (80 °C/W), and impedance stability across 0.5–6.0 GHz. Failure to fully ground the paddle degrades return loss and increases insertion loss in the HMC973LP3E.

Is the HMC973LP3E bidirectional, and what happens if RF is applied to RFOUT instead of RFIN?

No-the HMC973LP3E is explicitly unidirectional. Optimal linearity (+35 dBm IP3) and specified attenuation behavior are guaranteed only when RF input is applied to Pin 10 (RFIN). Applying RF to Pin 3 (RFOUT) results in degraded return loss, unpredictable attenuation, and potential distortion; the device is not characterized or warranted for reverse operation.

Does the HMC973LP3E require external blocking capacitors on RFIN and RFOUT?

Yes-both RFIN (Pin 10) and RFOUT (Pin 3) are DC-coupled 50 Ω ports. If the connected RF line carries DC bias other than 0 V, a series blocking capacitor must be placed in-line to prevent DC path disruption and ensure proper 50 Ω termination. Typical values are 100 pF (C1, C2) as shown in the evaluation PCB schematic for HMC973LP3E.

What is the maximum RF input power the HMC973LP3E can handle without damage?

The absolute maximum RF input power for the HMC973LP3E is +29 dBm (794 mW), as specified in the Absolute Maximum Ratings table. Continuous operation above this level risks permanent GaAs FET degradation. For reliable linear operation, the datasheet specifies +30 dBm input power for 1 dB compression-exceeding that causes measurable gain compression in the HMC973LP3E.

How does temperature affect attenuation accuracy in the HMC973LP3E?

Attenuation vs. Vctrl curves shift with temperature: at 0.5 GHz, attenuation deviates by ±1.5 dB between –40 °C and +85 °C for a fixed Vctrl. At 6 GHz, deviation increases to ±3 dB. Designers must calibrate Vctrl vs. attenuation per temperature zone or implement closed-loop feedback when sub-dB accuracy is required across the full –40 °C to +85 °C range of the HMC973LP3E.