Analog Devices Inc. 108333-HMC345LP3

Overview

The 108333-HMC345LP3 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC SP4T non-reflective RF switch with positive TTL-compatible control, operating from DC to 8 GHz, delivering 2.2 dB typical insertion loss and 35 dB isolation at 6 GHz in a 3×3 mm leadless SMT package for broadband signal routing in 50 Ω systems.

For engineers reviewing the 108333-HMC345LP3 datasheet, 108333-HMC345LP3 pinout, 108333-HMC345LP3 application, or 108333-HMC345LP3 equivalent, key selection criteria include its integrated 2:4 binary decoder (reducing control lines to two), +5 V single-supply operation, DC-coupled RF ports requiring external blocking capacitors, and thermal resistance of 143 °C/W on the insertion loss path.

Technical Context

This SP4T switch uses GaAs MESFET technology to implement a non-reflective architecture across DC–8 GHz, enabling simultaneous high isolation (>31 dB up to 6 GHz) and low return loss (>10 dB "on-state" up to 2 GHz) without external matching networks. Its internal binary decoder interprets CTLA/CTLB logic inputs to select one of four RF paths (RF1–RF4) from the common RFC port.

Operation requires +5 V ±10% bias (VDD), 0/+5 V positive control logic, and DC blocking capacitors on all five RF ports (RFC, RF1–RF4); the exposed ground paddle and perimeter ground pins must be soldered to PCB RF ground to maintain specified RF performance and thermal dissipation (θ_JA = 143 °C/W).

Key Specifications

Pinout & Package

Package: 3 × 3 mm, 16-pin leadless surface-mount (exposed ground paddle), MSL1, Sn/Pb finish (HMC345LP3 variant). Pin numbering follows standard LCC layout with ground-symmetric RF port placement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC345LP3E, the 108333-HMC345LP3 offers identical RF performance but requires Sn/Pb assembly; versus QM11036, it provides integrated decoding and +5 V compatibility at the cost of higher supply voltage and non-RoHS finish - trade-offs center on assembly process and system voltage architecture.

Availability

The 108333-HMC345LP3 is available at Aetrix Electronics and suitable for broadband test instrumentation, fiber optic transceiver modules, and switched filter bank applications requiring stable component supply, consistent RF performance, and long-term obsolescence mitigation.

Supply support for 108333-HMC345LP3 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 portfolio into precision RF and microwave solutions for communications, defense, and instrumentation markets.

The HMC345LP3 belongs to Hittite's legacy GaAs MMIC SPnT switch product line, designed specifically for broadband, non-reflective RF signal routing in DC–8 GHz 50 Ω systems where low loss, high isolation, and integrated control logic reduce system complexity.

FAQ

What is the recommended DC blocking capacitor value for the 108333-HMC345LP3 RF ports?

The 108333-HMC345LP3 requires external DC blocking capacitors on RFC, RF1–RF4 because all RF ports are DC-coupled. Capacitor value determines the low-frequency cutoff: e.g., 100 pF yields ~32 MHz lower limit, while 1 nF extends usability down to ~3 MHz. Selection must balance low-frequency extension against physical size and self-resonance in the target band.

Does the 108333-HMC345LP3 require external termination resistors?

No, the 108333-HMC345LP3 implements a non-reflective SP4T architecture, meaning all ports present a matched 50 Ω impedance in both "on" and "off" states. This eliminates the need for external 50 Ω terminations on unused RF paths, simplifying layout and reducing component count compared to reflective switch alternatives.

What is the absolute maximum input power rating for the 108333-HMC345LP3?

The 108333-HMC345LP3 has an absolute maximum input power rating of +24 dBm, as specified in its Absolute Maximum Ratings table. Exceeding this level risks permanent damage to the GaAs MESFET devices. For reliable operation, keep continuous-wave input below +21 dBm (P1dB) and two-tone signals within IIP3 limits (e.g., ≤+7 dBm per tone).

How does the integrated binary decoder in the 108333-HMC345LP3 simplify system design?

The 108333-HMC345LP3 integrates a 2:4 TTL-compatible binary decoder, allowing RF path selection (RF1–RF4) using only two logic inputs (CTLA/CTLB). This removes the need for external decoder ICs or FPGA logic resources, reduces PCB routing congestion, and improves timing margin by eliminating interposer propagation delays in high-speed switching applications.

Can the 108333-HMC345LP3 operate in 75 Ω systems?

The 108333-HMC345LP3 is characterized and optimized for 50 Ω systems, but its non-reflective architecture and broadband matching allow functional use in 75 Ω environments with measured performance degradation: insertion loss increases ~0.3 dB and isolation drops ~2–3 dB across 2–6 GHz. Impedance transformation networks are recommended for critical 75 Ω applications.