Analog Devices Inc. HMC641LC4

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 with 0/−5 V TTL/CMOS control logic, 2.1 dB typical insertion loss at 12 GHz, and 42 dB isolation at 12 GHz-used in microwave radio front-ends and SATCOM transmit/receive path switching.

For engineers reviewing the HMC641LC4 datasheet, HMC641LC4 pinout, HMC641LC4 application, or HMC641LC4 equivalent, key selection criteria include broadband DC–20 GHz operation, integrated 2:4 binary decoder reducing control lines from four to two, on-chip 50 Ω terminations for isolated ports, low DC current consumption versus pin diode alternatives, and −40°C to +85°C operating temperature range.

Technical Context

The HMC641LC4 implements a monolithic GaAs pHEMT architecture with non-reflective topology, where all off-state RF ports are internally terminated to 50 Ω. Its integrated 2-bit binary decoder accepts two logic inputs (CTLA, CTLB) to select one of four RF paths (RF1–RF4) from the common RFC port.

Control interface operates at 0 V (low) and −5 V (high) with sub-2 µA input current per control line; bias is supplied via single Vss = −5 V ±10% rail. Switching speed is characterized by 15 ns rise/fall time and 88 ns turn-on/turn-off delay across DC–20 GHz.

Key Specifications

Pinout & Package

Package: 24-lead 4×4 mm ceramic surface-mount package with exposed ground paddle; alumina body, gold-over-nickel plating; MSL3 rated; marking "H641" followed by 4-digit lot code.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC641LC4, HMC641LP4 offers identical RF performance in a lower-cost plastic package but sacrifices hermeticity and thermal efficiency, while QM11035 extends bandwidth to 22 GHz but requires additional control logic and delivers 4 dB less isolation-making HMC641LC4 optimal for high-isolation, space-constrained, and legacy −5 V logic environments.

Availability

HMC641LC4 is available at Aetrix Electronics and suitable for telecom infrastructure, microwave radio transceivers, and SATCOM terminals requiring stable component supply across extended product lifecycles and controlled obsolescence management.

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 maintains its high-frequency RF portfolio, specializing in GaAs, GaN, and SiGe MMIC solutions for defense, aerospace, and communications markets.

The HMC641LC4 belongs to Hittite's legacy GaAs MMIC switch family, designed specifically for broadband, high-isolation, low-distortion RF path selection in demanding microwave systems where reliability and repeatability are critical.

FAQ

What is the recommended PCB layout practice for the HMC641LC4 ground connections?

All 11 ground pins (2,4,7,9,10,12,17,19,21,22,24) plus the exposed ground paddle must be soldered directly to a solid RF ground plane using multiple thermal vias. Per the datasheet, insufficient grounding degrades isolation and return loss-especially above 10 GHz. The evaluation board (P/N 126508) uses Rogers 4350 substrate with 50 Ω microstrip routing and ≥12 vias under the paddle. HMC641LC4 performance is highly dependent on this grounding integrity.

Does the HMC641LC4 require external blocking capacitors on its RF ports?

Yes-the RFC, RF1, RF2, RF3, and RF4 ports (pins 3,8,11,20,23) are DC-coupled and matched to 50 Ω, so external DC-blocking capacitors are mandatory if any connected RF line carries non-zero DC potential. Typical values are 100 pF for DC–6 GHz or 47 pF for 6–20 GHz; placement must be within 2 mm of the pad to avoid resonance. The HMC641LC4 itself contains no internal blocking capacitance.

What is the absolute maximum input power rating for the HMC641LC4?

The absolute maximum input power for the HMC641LC4 is +24 dBm, specified across DC–20 GHz. This limit applies regardless of signal modulation or duty cycle. Exceeding +24 dBm risks permanent damage to the GaAs pHEMT devices, especially under continuous-wave conditions. For pulsed operation, peak power must still remain ≤+24 dBm, and average power should stay below the 1 dB compression point (20 dBm typical at 0.25–20 GHz) to maintain linearity.

Can the HMC641LC4 operate with +3.3 V or +5 V control logic?

No-the HMC641LC4 requires strictly 0 V (logic low) and −5 V (logic high) control voltages per its Absolute Maximum Ratings and Control Voltage Table. Applying +3.3 V or +5 V to CTLA or CTLB will exceed the −0.5 V maximum allowed above Vss (−5 V), risking latch-up or permanent damage. Level-shifting circuitry (e.g., ADG901-based translator) is required to interface with positive-supply logic families.

What is the ESD sensitivity classification for the HMC641LC4?

The HMC641LC4 is classified as Class 1A per the Human Body Model (HBM), meaning it withstands ≥250 V but <500 V ESD stress. This low tolerance mandates strict handling: use grounded wrist straps, conductive foam storage, ionized air workstations, and avoid touching pins directly. The device is marked "ELECTROSTATIC SENSITIVE DEVICE" on its datasheet and packaging-failure to observe precautions may cause latent or catastrophic failure undetectable in functional test.