Analog Devices Inc. HMC641LC4TR

Overview

HMC641LC4 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. It delivers 2.1 dB insertion loss and 42 dB isolation at 12 GHz, features on-chip 50 Ω terminations for isolated ports, and integrates a binary 2:4 decoder to reduce control lines from four to two. It is used in microwave radio front-ends requiring broadband signal routing with fast TTL/CMOS-compatible switching.

For engineers reviewing the HMC641LC4 datasheet, HMC641LC4 pinout, HMC641LC4 application, or HMC641LC4 equivalent, key selection criteria include its -5 Vdc supply requirement, 0/–5 V logic interface, 15 ns rise/fall time, 88 ns switching delay, and non-reflective architecture enabling stable impedance during state transitions in high-frequency test and SATCOM systems.

Technical Context

The HMC641LC4 implements a monolithic GaAs pHEMT-based SP4T architecture with integrated on-die 50 Ω terminations on all off-state RF ports, eliminating external termination components. Its internal 2:4 binary decoder accepts two TTL/CMOS-compatible control inputs (CTLA, CTLB) to select one of four RF paths (RF1–RF4) from the common RFC port.

It operates with a single –5 Vdc bias (Vss) and draws only 1.7 mA typical supply current. The switch maintains DC-coupled 50 Ω RF ports (RFC, RF1–RF4), requiring external DC blocking capacitors when RF line DC potential differs from ground, and mandates grounding of all 24 package leads and the exposed paddle per RF design best practices.

Key Specifications

Pinout & Package

Package: 24-lead 4×4 mm ceramic surface-mount package with alumina body, gold-over-nickel plating, MSL3 rating, and exposed ground paddle requiring soldering to PCB RF ground.

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 HMC641LC4 offers identical RF performance in a standardized 4×4 mm ceramic SMT package with single –5 V bias, making it optimal for space-constrained microwave modules where layout reuse and thermal management simplicity are critical.

Availability

HMC641LC4 is available at Aetrix Electronics and suitable for telecom infrastructure, microwave radio & VSAT, and test instrumentation requiring stable component supply, long-term obsolescence mitigation, and traceable sourcing for RF front-end designs.

Supply support for HMC641LC4 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 HMC641LC4 belongs to Hittite's legacy GaAs MMIC SPnT switch product line, designed specifically for broadband, high-isolation, low-loss signal routing in microwave and millimeter-wave systems where non-reflective behavior and minimal control complexity are essential.

FAQ

What is the recommended DC blocking configuration for HMC641LC4 RF ports?

Each RF port (RFC, RF1–RF4) is DC-coupled and matched to 50 Ω, so external DC blocking capacitors are required if the connected RF line has non-zero DC potential. Use high-Q, low-ESL 0402 or 0201 capacitors rated for >20 GHz operation; typical values range from 100 pF to 1000 pF depending on low-frequency cutoff requirements. The HMC641LC4 evaluation board (126511) uses 1000 pF capacitors.

Does HMC641LC4 require external termination resistors?

No, the HMC641LC4 does not require external termination resistors. It integrates on-chip 50 Ω terminations for all off-state RF ports (e.g., when RFC connects to RF1, RF2–RF4 are internally terminated). This non-reflective architecture eliminates discrete terminations, improves high-frequency match stability, and reduces bill-of-materials count in microwave assemblies.

What is the absolute maximum input power rating for HMC641LC4?

The absolute maximum input power for HMC641LC4 is +24 dBm, as specified in the Absolute Maximum Ratings table. Exceeding this level risks permanent damage. For linear operation, the 1 dB compression point is +20 dBm at 0.25–20 GHz, and the input third-order intercept point is +39 dBm under two-tone +14 dBm conditions in the same band.

Can HMC641LC4 be controlled directly by 3.3 V CMOS logic?

No, HMC641LC4 cannot be driven directly by 3.3 V CMOS logic. Its control inputs (CTLA, CTLB) require 0 V (low) and –5 V (high) levels, with valid voltage ranges of –2.5 V to 0 V (low) and –5 V to –3.8 V (high). A level-shifting circuit or dedicated –5 V driver is required to interface with standard 3.3 V or 5 V logic families.

What thermal management guidelines apply to HMC641LC4?

HMC641LC4 requires robust thermal management: the exposed ground paddle and all 11 ground pins (2,4,7,9,10,12,17,19,21,22,24) must be soldered to a low-thermal-resistance PCB ground plane with ≥6 thermal vias (0.3 mm diameter) connecting to inner/outer ground layers. Thermal resistance from channel to die bottom is 199 °C/W (insertion path); mounting to an external heatsink is recommended for continuous >+70 °C ambient operation.