Analog Devices Inc. HMC322-SX

Overview

HMC322-SX from Hittite Microwave Corporation (now part of Analog Devices) is a GaAs MMIC SP8T non-reflective switch operating from DC to 8 GHz, delivering 2.5 dB typical insertion loss and >30 dB isolation at 6 GHz with integrated 3:8 TTL decoder logic. It uses -5 V fixed bias and 0/–5 V negative control voltage, and is designed for 50-Ω or 75-Ω RF signal routing in broadband test instrumentation and wireless infrastructure.

For engineers reviewing the HMC322-SX datasheet, HMC322-SX pinout, HMC322-SX application, or HMC322-SX equivalent, key selection criteria include its SP8T non-reflective architecture, -5 V bias requirement, 24-lead 4×4 mm QFN package, DC–8 GHz bandwidth, and integrated binary decoder reducing control lines to three.

Technical Context

The HMC322-SX implements a GaAs MESFET-based SP8T switch topology with on-die non-reflective termination for all off-state ports, enabling stable impedance matching across DC–8 GHz. Its integrated 3:8 TTL decoder accepts A/B/C inputs to select one of eight RF paths (RF1–RF8) to the common RFC port.

It operates with a fixed VEE = –5 V ±10% supply and requires negative logic control (–5 V for HIGH, 0 V for LOW), compatible with HCT-family logic when Vee is tied to the logic gate's Vee pin. Switching speed is characterized by 50 ns tRISE/tFALL and 150 ns tON/tOFF over full frequency range.

Key Specifications

Pinout & Package

Package: 24-lead leadless QFN, 4 mm × 4 mm body, exposed ground paddle, MSL1 rating. Requires soldering of all ground leads 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 SP8T RF switch applications.

Compared with HMC322-SX, HMC322LP4E offers identical RF functionality with RoHS-compliant packaging, while QM11036 trades bandwidth and integrated decoding for lower-voltage control-making HMC322-SX optimal for DC–8 GHz systems needing minimal external logic and stable negative-bias operation.

Availability

HMC322-SX is available at Aetrix Electronics and suitable for broadband test instrumentation, fiber optic transceiver modules, switched filter banks, and sub-8 GHz wireless infrastructure requiring stable component supply and long-term obsolescence management.

Supply support for HMC322-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

Hittite Microwave Corporation, acquired by Analog Devices in 2014, specialized in high-performance RF, microwave, and millimeter-wave ICs for defense, communications, and instrumentation markets.

The HMC322-SX belongs to Hittite's GaAs MMIC SPnT switch product line, engineered for broadband, non-reflective RF signal routing in systems demanding high isolation, low loss, and integrated logic reduction.

FAQ

What is the control voltage scheme required for HMC322-SX?

HMC322-SX requires negative logic control: –5 V (±0.5 V) for HIGH state and 0 V for LOW state on CTLA, CTLB, and CTLC pins. The device also needs a fixed –5 V ±10% bias on VEE (pin 8). This matches HCT-family logic when their Vee pin is tied to –5 V, enabling direct TTL interface without level-shifting circuitry.

Does HMC322-SX support 75-ohm systems?

Yes, HMC322-SX is explicitly specified for use in both 50-ohm and 75-ohm systems. Its internal matching and non-reflective architecture maintain consistent return loss and isolation performance across either impedance, making it suitable for CATV, broadcast, and video distribution applications alongside telecom infrastructure.

What is the thermal resistance and maximum power dissipation of HMC322-SX?

HMC322-SX has a thermal resistance of 187 °C/W and a maximum continuous power dissipation of 0.348 W at 85 °C ambient, derating linearly at 5.34 mW/°C above that temperature. The exposed paddle must be soldered to a thermally robust PCB ground plane to achieve this rating and ensure reliable operation under sustained RF drive.

Is an external blocking capacitor required on RF ports of HMC322-SX?

Yes - all RF ports (RF1–RF8 and RFC) are DC-coupled and matched to 50 Ω, so external DC-blocking capacitors are mandatory if any connected RF line carries DC potential. Failure to do so may forward-bias internal FET junctions, degrading performance or causing permanent damage.

How does the integrated 3:8 decoder in HMC322-SX reduce system complexity?

The integrated 3:8 decoder allows HMC322-SX to select one of eight RF paths using only three control lines (CTLA, CTLB, CTLC), eliminating the need for external decoder ICs or FPGA logic resources. This reduces PCB area, BOM count, and routing complexity - especially valuable in space-constrained RF modules where GPIO pins are limited.