Analog Devices Inc. HMC641A

Overview

HMC641A from Analog Devices is a GaAs monolithic microwave integrated circuit (MMIC) nonreflective SP4T RF switch operating from 0.1 GHz to 18 GHz, delivering 2.1 dB typical insertion loss and 42 dB typical isolation at 12 GHz, with integrated 2-to-4 line decoder for logic control - used in broadband test instrumentation and military radar front-ends.

For engineers reviewing the HMC641A datasheet, HMC641A pinout, HMC641A application, or HMC641A equivalent, this page provides verified electrical specs, validated package mapping, confirmed control interface behavior, and real-world RF switching performance under −5 V to −3 V supply conditions.

Technical Context

The HMC641A implements a single-pole, four-throw topology using GaAs FETs with internal 50 Ω termination on all off-state RF paths, enabling nonreflective operation across DC-coupled 50 Ω systems. Its on-chip binary decoder accepts two negative logic inputs (CTRLA/CTRLB) to select one of four RF throw paths to the common RFC port.

Operation requires a negative supply (VSS = −5 V to −3 V) applied before digital control signals to prevent ESD structure damage; all eight pads are surface-mountable bare-die terminals with dc-coupled RF interfaces and no external blocking capacitors needed when RF lines sit at 0 V dc.

Key Specifications

Pinout & Package

Package: 8-pad bare die [CHIP], 1.92 mm × 1.60 mm × 0.102 mm (C-8-9), back-metallized for eutectic or conductive epoxy attachment to ground plane.

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 HMC641A uniquely combines 18 GHz bandwidth, integrated decoder, and bare-die form factor - making it irreplaceable in high-frequency military and test equipment where size, speed, and frequency coverage are co-constrained.

Availability

HMC641A is available at Aetrix Electronics and suitable for microwave radio development, radar front-end prototyping, and broadband test instrumentation requiring stable component supply across extended temperature ranges (−55°C to +85°C).

Supply support for HMC641A 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, Inc. is a global leader in high-performance analog, mixed-signal, and RF ICs, serving precision instrumentation, communications, and defense markets since 1965.

The HMC641A belongs to the Hittite Microwave product line (acquired by Analog Devices in 2014), engineered specifically for broadband RF switching in demanding microwave and millimeter-wave systems where nonreflective behavior and high power integrity are mandatory.

FAQ

What is the correct power-up sequence for the HMC641A?

The HMC641A requires strict sequencing: first bond the die bottom to ground, then apply VSS (−5 V to −3 V), then assert CTRLA/CTRLB logic levels, and finally apply RF signal. Applying CTRLA/CTRLB before VSS risks forward-biasing ESD protection diodes and causing irreversible damage to the HMC641A. This sequence is explicitly defined in the Theory of Operation section of the Rev. D datasheet.

Does the HMC641A require external DC blocking capacitors on its RF ports?

No - all RF ports (RFC, RF1–RF4) are dc-coupled to 0 V and internally matched to 50 Ω, so no external DC blocking capacitors are needed when the RF transmission lines operate at 0 V dc potential. This feature is confirmed in the Pin Configuration table and Functional Block Diagram of the HMC641A datasheet Rev. D, enabling true baseband-capable switching.

What is the maximum RF input power the HMC641A can handle in hot-switching mode?

At VSS = −5 V, the HMC641A supports 20 dBm RF input power during hot switching (changing state while RF is present), as specified in the Absolute Maximum Ratings table. Exceeding this level risks gate oxide degradation or thermal runaway. The HMC641A datasheet Rev. D explicitly defines this limit and notes derating is required below 250 MHz per Figure 2.

Can the HMC641A be used with positive supply voltages?

No - the HMC641A is designed exclusively for negative supply operation. Its VSS pin must be biased between −5 V and −3 V; applying positive voltage or grounding VSS will disable internal FET biasing and render the HMC641A nonfunctional. The General Description and Absolute Maximum Ratings sections of the datasheet confirm −7 V is the absolute lower limit, with no upper bound above 0 V specified or supported.

How does the integrated 2-to-4 line decoder affect control interface design?

The integrated decoder reduces control wiring from four independent lines to just two (CTRLA and CTRLB), interpreting them as binary addresses to select RF1–RF4 per Table 4. This eliminates external logic gates, saves PCB area, and ensures deterministic state transitions - a key advantage over discrete switch + decoder solutions. The HMC641A truth table is fully documented in Rev. D, Page 8.