Microchip Technology UM4001B

Overview

UM4001B from Microsemi is a high-power PIN diode designed for RF switching and attenuation in HF–S-band systems. It features 200 V reverse voltage rating, 0.5 Ω typical series resistance at 100 MHz/100 mA, >5 µs carrier lifetime, low 3 pF capacitance at 100 V reverse bias, and operates in stud-mounted Style B package. It enables low-distortion RF control in phase shifters and duplexers.

For engineers reviewing the UM4001B datasheet, UM4001B pinout, UM4001B application, or UM4001B equivalent, key selection criteria include reverse voltage rating, thermal path performance under pulsed RF loads, carrier lifetime impact on RF linearity, and compatibility with automatic insertion equipment in high-reliability microwave assemblies.

Technical Context

The UM4001B uses a non-cavity, thermally matched silicon PIN structure with thick intrinsic region to sustain high peak RF voltages beyond applied reverse bias. Its long carrier lifetime (>5 µs) and low series resistance (0.5 Ω typ.) support efficient RF current control with minimal DC bias.

Designed for operation up to S-band (3 GHz), it maintains stable parallel resistance (>10 kΩ at 100 V/100 MHz) and low capacitance (≤3 pF) across reverse bias, enabling predictable impedance switching in filter and cavity networks.

Key Specifications

Pinout & Package

UM4001B is housed in Style B package: isolated stud-mount metal case with anode and cathode terminals on opposite ends of the cylindrical body. Thermal path optimized for direct stud-to-heat-sink conduction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-power RF PIN diode applications.

Compared with UM4001B, UM4901B offers higher continuous power headroom without layout change, while UMX4001B provides identical RF performance with RoHS-compliant finish-both retain the same Style B mechanical interface and bias requirements.

Availability

UM4001B is available at Aetrix Electronics and suitable for UHF phase shifters, megawatt radar duplexers, antenna selectors, and coupler filter networks requiring stable component supply across extended production lifecycles.

Supply support for UM4001B 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

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog and RF components for defense, aerospace, and communications infrastructure.

The UM4000 series was developed specifically for high-power microwave switching applications demanding robust thermal performance, low distortion, and proven field reliability in radar and EW systems.

FAQ

What is the maximum reverse voltage rating for UM4001B?

The UM4001B has a reverse voltage rating of 200 V, verified per Microsemi's absolute maximum ratings table. This rating allows the UM4001B to safely handle RF peak voltages significantly exceeding the applied DC reverse bias in HF–S-band switching applications, supporting reliable operation in high-isolation RF paths.

Does UM4001B require a heatsink in continuous operation?

Yes - UM4001B must be mounted to a thermally conductive surface (e.g., copper stud or heatsink) to maintain junction temperature within limits. At 25°C stud temperature, its rated power dissipation is 25 W; derating is required above that temperature per the published thermal resistance curve. Proper thermal interface material is recommended for consistent performance.

Is UM4001B compatible with automated PCB assembly processes?

Yes - UM4001B in Style B package is explicitly qualified for compatibility with automatic insertion equipment, as stated in the manufacturer's KEY FEATURES list. Its mechanical symmetry and terminal geometry support pick-and-place and axial insertion without modification, making it suitable for high-volume antenna module production.

How does carrier lifetime affect UM4001B's RF performance?

UM4001B's carrier lifetime exceeds 5 µs, enabling efficient RF current control with low DC bias current. This long lifetime reduces harmonic generation and intermodulation distortion in high-level RF switching, directly improving linearity in phase shifters and attenuators where signal fidelity is critical.

What is the typical series resistance of UM4001B at RF frequencies?

The typical series resistance of UM4001B is 0.5 Ω measured at 100 MHz and 100 mA forward current. This low R_S minimizes insertion loss in series-switch configurations and contributes to high power-handling capability with reduced self-heating during RF conduction.