Analog Devices Inc. HMC347-SX

Overview

HMC347-SX from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC SPDT non-reflective switch die operating from DC to 20 GHz, delivering 1.6 dB insertion loss and >40 dB isolation at 20 GHz with dual -5/0 V negative logic control. It features coplanar RF I/Os, no Vee supply, zero current draw, and is used in high-frequency signal routing for fiber optics transceivers and microwave radio front-ends.

For engineers reviewing the HMC347-SX datasheet, HMC347-SX pinout, HMC347-SX application, or HMC347-SX equivalent, key selection criteria include its DC–20 GHz bandwidth, non-reflective architecture, -5/0 V control compatibility, 1.3 × 0.8 mm die size, and suitability for space-constrained RF modules requiring stable switching performance across military and VSAT bands.

Technical Context

The HMC347-SX implements on-chip via hole structures to achieve broadband non-reflective operation from DC to 20 GHz, enabling simultaneous high isolation (>40 dB at 20 GHz) and low insertion loss (1.6 dB at 20 GHz). Its MESFET-based design eliminates DC blocking requirements on RFC, RF1, and RF2 ports.

Control logic uses two independent negative-voltage lines (CTRLA/CTRLB) with defined high/low thresholds (-5 V typ. for "Low", 0 to -0.2 V for "High") and no static current draw. Switching speed is characterized by 3 ns tRISE/tFALL and 6 ns tON/tOFF over full frequency range.

Key Specifications

Pinout & Package

Package: Bare GaAs MMIC die, 1.3 mm × 0.8 mm × 0.1 mm, back-metallized for eutectic or conductive epoxy mounting. Supplied in WP-8 waffle pack.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SPDT switch applications.

Compared with HMC347-SX, HMC547LP3E offers improved RF specs in a packaged form but sacrifices die-level customization, while QM11036 shifts to positive logic and reduces insertion loss at the cost of control interface redesign-neither is pin-compatible, and both require layout and driver changes.

Availability

HMC347-SX is available at Aetrix Electronics and suitable for fiber optics transceivers, microwave radio front-ends, and military radar TR modules requiring stable component supply across extended temperature ranges and high-frequency reliability.

Supply support for HMC347-SX 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 precision RF and microwave solutions for defense, communications, and instrumentation markets.

The HMC347-SX belongs to Hittite's legacy GaAs MMIC switch family, engineered for broadband non-reflective signal routing in millimeter-wave systems where DC coupling, ultra-low current, and minimal footprint are critical.

FAQ

What is the operating temperature range for the HMC347-SX?

The HMC347-SX is specified for operation from -55°C to +85°C ambient temperature, with channel temperature rated up to 150°C. This range supports deployment in outdoor microwave radios, airborne radar subsystems, and space-qualified VSAT terminals where thermal cycling and extreme ambient conditions are present. The HMC347-SX die must be mounted to an RF ground plane with thermally conductive epoxy or eutectic solder to maintain junction temperature within limits under RF power dissipation.

Does the HMC347-SX require external DC blocking capacitors on its RF ports?

Yes, the HMC347-SX RF ports (RFC, RF1, RF2) are DC-coupled and matched to 50 Ω, so external blocking capacitors are required if the connected RF line has a DC potential other than 0 V. This is necessary to prevent bias disruption or damage to upstream/downstream components. The HMC347-SX itself draws no DC current, but improper DC blocking can shift operating points in adjacent amplifiers or mixers. Refer to the HMC347-SX interface schematic for recommended capacitor values and placement.

What is the absolute maximum RF input power rating for the HMC347-SX?

The HMC347-SX has an absolute maximum RF input power rating of +27 dBm when control voltages are set to -5 V. Exceeding this level risks permanent damage to the GaAs MESFET structure, especially under continuous wave conditions. For reliable operation, the datasheet recommends limiting input power to ≤23 dBm (P1dB) to maintain linear performance. The HMC347-SX thermal resistance is 440 °C/W on the insertion loss path, so adequate heat sinking is essential at high RF power levels.

How does the HMC347-SX achieve non-reflective behavior without external termination resistors?

The HMC347-SX achieves non-reflective behavior using on-die termination networks integrated into the GaAs MMIC structure, which present a 50 Ω load to the off-state RF port. This eliminates the need for external 50 Ω resistors and associated parasitics, preserving broadband match and saving PCB area. The implementation relies on on-chip via hole structures that enable effective grounding across DC–20 GHz. As a result, the HMC347-SX maintains >10 dB return loss in the "on" state and avoids signal reflections that could degrade VSWR in cascaded RF stages.

Can the HMC347-SX be used in DC-coupled baseband applications?

Yes, the HMC347-SX supports true DC-coupled operation from 0 Hz, making it suitable for baseband switching in instrumentation, arbitrary waveform generators, and I/Q modulator calibration paths. Its MESFET architecture allows gate-controlled conduction without DC bias dependency on the RF path. However, external DC blocking remains mandatory if any connected device imposes non-zero DC offset on RFC, RF1, or RF2. The HMC347-SX's ability to pass DC enables seamless integration in systems requiring phase-coherent signal routing across baseband and RF bands.