Microchip Technology UM4302B

Overview

UM4302B from Microsemi is a high-voltage, low-distortion PIN diode designed for RF switching and linear attenuator applications in HF–1 GHz systems. It features 200 V reverse voltage rating, 2.2 pF maximum capacitance at 100 V/1 MHz, 1.5 Ω max series resistance at 100 mA/100 MHz, and 20 W power dissipation in stud-mounted configuration (Style C). It operates with carrier lifetime ≥6.0 μs and I-region width ≥250 μm.

For engineers reviewing the UM4302B datasheet, UM4302B pinout, UM4302B application, or UM4302B equivalent, key selection criteria include RF voltage hold-off capability, thermal resistance in stud-mount packages, distortion-sensitive attenuator linearity, and compatibility with surface-mount assembly (Style SM variant available).

Technical Context

The UM4302B employs a thick intrinsic region to achieve transit time frequencies below 5 MHz-enabling ultra-low harmonic distortion in analog RF signal paths. Its low thermal resistance construction (7.5 °C/W in Style C) supports stable operation under continuous 20 W dissipation at 25 °C stud temperature.

As a discrete PIN diode, it functions as a voltage-controlled RF resistor: forward bias reduces series resistance (down to 1.5 Ω), while reverse bias maintains high impedance (>200 kΩ parallel resistance at 100 V), enabling precise attenuation and high-isolation switching up to 1 GHz.

Key Specifications

Pinout & Package

UM4302B is offered in multiple package styles including stud-mounted Style C (isolated, thermally optimized) and surface-mount Style SM. The Style C package uses two axial leads: anode and cathode, mounted via insulated stud to heatsink for optimal thermal management. Style SM provides solderable SMT terminals compatible with automated placement.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PIN diode switching and attenuation applications.

Compared with UM4302B, UM4302C offers superior thermal grounding for chassis-integrated RF modules, while UMX4302SM enables SMT scalability at the cost of reduced thermal headroom-both retain identical RF linearity and voltage ratings.

Availability

UM4302B is available at Aetrix Electronics and suitable for HF–VHF RF switching, precision linear attenuators, and high-isolation T/R modules requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for UM4302B 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 RF, microwave, and timing solutions for defense, aerospace, and industrial markets.

The UM4300 series was engineered specifically for distortion-critical RF control functions-including programmable attenuators and high-power switching-where transit-time-limited linearity and thermal robustness are non-negotiable.

FAQ

What is the maximum RF frequency range supported by the UM4302B?

The UM4302B is characterized for operation from HF up to beyond 1 GHz. Its 2.2 pF capacitance and 1.5 Ω series resistance support stable RF performance through 1 GHz in properly matched circuits. Measured isolation and insertion loss remain effective up to 3 GHz in optimized layouts, though datasheet specifications are guaranteed only to 1 GHz.

Does the UM4302B require a heatsink in continuous 20 W operation?

Yes-the UM4302B achieves its full 20 W power rating only when mounted to a heatsink via isolated stud (Style C). In Style B (free-air lead-temperature condition), its rating drops to 10 W. Thermal resistance is 7.5 °C/W for Style C at 25 °C stud temperature; proper heatsinking is mandatory for sustained high-power use.

How does the UM4302B differ from the UM7302 in practical RF design?

The UM4302B has higher power handling (20 W vs. 7.5 W) and lower series resistance (1.5 Ω vs. 3.0 Ω), making it preferred for high-current attenuators and switches. The UM7302 offers lower capacitance (0.7 pF vs. 2.2 pF), benefiting ultra-broadband or >500 MHz applications where capacitive loading must be minimized.

Is the UM4302B RoHS compliant?

The standard UM4302B is not RoHS compliant. For RoHS compliance, specify UMX4302B-identical electrical and thermal performance with lead-free terminations and compliant packaging. UMX4302B is available in Style B and Style SM variants; consult factory for UMX4302C availability.

Can the UM4302B be used in series-shunt RF switch configurations?

Yes-the UM4302B is routinely deployed in series-shunt switch topologies. Its 200 V reverse rating, 200 kΩ parallel resistance, and 1.5 Ω on-resistance enable >45 dB isolation and <0.4 dB insertion loss at 100 MHz. Layout must minimize stray inductance on anode/cathode traces to preserve high-frequency performance.