Analog Devices Inc. HMC641

Overview

HMC641 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC SP4T non-reflective switch chip operating from DC to 18 GHz, delivering 2.1 dB insertion loss and 42 dB isolation at 12 GHz, with integrated 2:4 TTL decoder and -5 Vdc Vss bias. It serves as a broadband RF signal routing element in microwave front-ends requiring low-loss path selection and high off-state rejection.

For engineers reviewing the HMC641 datasheet, HMC641 pinout, HMC641 application, or HMC641 equivalent, key selection considerations include its DC–18 GHz bandwidth, non-reflective architecture, -5 V control interface, 1.92 × 1.60 mm die size, and compatibility with TTL/CMOS logic when Vee = -5 V.

Technical Context

The HMC641 implements a monolithic GaAs PHEMT SP4T switch with on-die binary decoder, reducing external control lines from four to two (A and B). Its non-reflective topology terminates all off-state ports into 50 Ω via internal resistors, ensuring stable impedance across all switching states.

It operates with fixed -5 Vdc Vss supply and accepts 0/-5 Vdc TTL-compatible control inputs. All RF ports (RFC, RF1–RF4) are DC-coupled, 50 Ω matched, and require external blocking capacitors if DC bias differs from ground.

Key Specifications

Pinout & Package

Package: Bare GaAs die (1.92 × 1.60 × 0.10 mm), gold bond pads, grounded backside metallization, supplied in WP-18 waffle pack.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC641LP4E and QM11036, the HMC641 provides widest bandwidth (DC–18 GHz), lowest insertion loss among bare-die SP4Ts in its class, and unique non-reflective behavior-critical for phase-coherent and wideband test systems where impedance discontinuity must be avoided.

Availability

HMC641 is available at Aetrix Electronics and suitable for telecom infrastructure, microwave radio & VSAT, military & space hybrids, and test instrumentation requiring stable component supply and long-term sourcing continuity.

Supply support for HMC641 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 portfolio, specializing in GaAs, GaN, and SiGe MMICs for defense, communications, and instrumentation markets.

The HMC641 belongs to Hittite's legacy SP4T switch product line, engineered specifically for broadband non-reflective RF signal routing in hybrid microwave assemblies and high-reliability military platforms.

FAQ

What is the recommended bias configuration for HMC641?

The HMC641 requires a fixed -5 Vdc Vss supply (±10%) applied to Pad 6, with control inputs A and B referenced to this rail. TTL logic driving CTLA/CTLB must use -5 Vdc as Vee; typical current draw is 3 mA. External blocking capacitors are mandatory on all RF pads if DC potential differs from ground.

Does HMC641 support DC-coupled operation?

Yes, HMC641 supports true DC-coupled operation on all RF ports (RFC, RF1–RF4), with 50 Ω impedance match from DC through 18 GHz. However, external DC blocking capacitors are required unless the connected circuitry shares identical DC bias levels across all ports.

How is thermal management handled for HMC641 in high-power applications?

HMC641 features a grounded gold backside metallization that must be thermally bonded to the system ground plane. Its channel-to-die-bottom thermal resistance is 188 °C/W for the insertion path, enabling continuous operation at +85 °C ambient when dissipating up to 15 mW under typical RF conditions.

Can HMC641 be driven directly by standard CMOS logic?

No-standard 0/+3.3 V or 0/+5 V CMOS outputs cannot drive HMC641 directly. It requires negative control voltages (-5 V for logic low, 0 V for logic high). Interface is compatible only with -5 V-referenced TTL families (e.g., 74HCT) or level-shifted CMOS signals.

What is the maximum RF input power rating for HMC641?

HMC641 has an absolute maximum input power rating of +24 dBm. At +21 dBm input (1 dB compression point), it delivers linear operation up to 18 GHz; derating is required above +21 dBm to avoid gain compression or distortion in critical receive paths.