Analog Devices Inc. HMC641ALC4

Overview

HMC641ALC4 from Analog Devices (formerly Hittite Microwave) is a GaAs pHEMT SP4T non-reflective MMIC switch in a 4×4 mm ceramic SMT package, operating from DC to 20 GHz with 2.1 dB typical insertion loss and 42 dB isolation at 12 GHz, controlled by 0/−5 V logic for telecom infrastructure and test instrumentation signal routing.

For engineers reviewing the HMC641ALC4 datasheet, HMC641ALC4 pinout, HMC641ALC4 application, or HMC641ALC4 equivalent, key selection criteria include broadband RF switching performance, integrated 2:4 TTL decoder reducing control lines, non-reflective architecture with on-chip terminations, and −40°C to +85°C operational range.

Technical Context

The HMC641ALC4 implements a monolithic GaAs pHEMT architecture with integrated binary decoder, enabling four RF paths (RFC↔RF1–RF4) to be selected via two TTL/CMOS-compatible control inputs (CTLA, CTLB) referenced to Vss = −5 V. All isolated ports are internally terminated to 50 Ω.

It operates as a non-reflective switch: when any RF path is "on", the three unused RF ports present ≥19 dB return loss across DC–20 GHz due to on-die 50 Ω terminations, eliminating external termination components and preserving system VSWR integrity.

Key Specifications

Pinout & Package

Package: 24-lead 4×4 mm ceramic surface-mount package with exposed ground paddle; body material alumina; gold-over-nickel plating; MSL3 rating; marking "H641A" followed by 4-digit lot code.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SP4T RF switch applications.

Compared with HMC7992LP3DE and QM11036, the HMC641ALC4 uniquely balances DC–20 GHz operation, integrated decoder, and non-reflective architecture in a compact 4×4 mm package-making it optimal for mid-band microwave systems needing simplified control and stable impedance across switching states.

Availability

HMC641ALC4 is available at Aetrix Electronics and suitable for telecom infrastructure, microwave radio & VSAT, and test instrumentation requiring stable component supply, consistent RF performance, and long-term obsolescence management.

Supply support for HMC641ALC4 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/Microwave portfolio into precision analog and RF solutions for communications, defense, and instrumentation markets.

The HMC641ALC4 belongs to Hittite's legacy GaAs MMIC SPnT switch product line, designed specifically for broadband non-reflective signal routing in microwave systems where impedance stability, low loss, and fast switching are critical.

FAQ

What is the recommended PCB layout practice for the HMC641ALC4 ground connections?

All ground pins (2,4,7,9,10,12,17,19,21,22,24) and the exposed ground paddle must be soldered directly to a solid RF ground plane using ≥12 evenly spaced vias. This minimizes inductance and ensures return current paths remain localized, preserving the HMC641ALC4's specified isolation and return loss performance across DC–20 GHz.

Does the HMC641ALC4 require external DC blocking capacitors on its RF ports?

Yes - the HMC641ALC4 RF ports (RFC, RF1–RF4) are DC-coupled and matched to 50 Ω, so external DC blocking capacitors are required whenever the RF line potential differs from 0 V. Typical values are 100 pF for DC–6 GHz or 47 pF for 6–20 GHz, placed as close as possible to the HMC641ALC4 pads.

What is the maximum input power the HMC641ALC4 can handle in terminated paths?

The HMC641ALC4 supports +23 dBm maximum input power on terminated (off-state) RF paths. This rating ensures robustness against reflected energy during switching transients or mismatched loads, protecting the internal terminations and maintaining reliability in high-power SATCOM and radar applications using the HMC641ALC4.

How does the integrated 2:4 decoder in the HMC641ALC4 simplify system design?

The integrated 2:4 decoder reduces the number of required logic control lines from four to two (CTLA and CTLB), eliminating external decoding logic. This saves FPGA/CPLD I/O resources, reduces PCB routing complexity, and improves timing margin - a key advantage over discrete decoder + switch solutions when implementing the HMC641ALC4 in space-constrained microwave modules.

What is the operating temperature range for the HMC641ALC4, and how does performance vary across it?

The HMC641ALC4 operates from −40°C to +85°C. Insertion loss increases by ≤0.3 dB and isolation decreases by ≤3 dB from +25°C to +85°C across DC–12 GHz, as verified in the HMC641ALC4 datasheet plots. These variations are fully characterized and accounted for in the HMC641ALC4's guaranteed specifications.