Microchip Technology UM7301B

Overview

UM7301B from Microsemi is a high-voltage, low-capacitance PIN diode designed for RF switching and linear attenuator applications in HF–1 GHz systems. It features 200 V reverse voltage rating, 0.7 pF maximum capacitance at 100 V/1 MHz, 3.0 Ω max series resistance at 100 mA/100 MHz, and 4.0 μs minimum carrier lifetime - enabling low-distortion signal control in broadband RF front-ends.

For engineers reviewing the UM7301B datasheet, UM7301B pinout, UM7301B application, or UM7301B equivalent, key selection criteria include its 200 V blocking capability, sub-1 pF capacitance, thermal resistance of 4 °C/W (Style B), and suitability for surface-mount or stud-mounted linear attenuators requiring <−80 dBc harmonic distortion.

Technical Context

The UM7301B employs a thick intrinsic (I) region (≥250 μm) to achieve low transit-time distortion below 5 MHz, supporting high-linearity RF attenuation. Its non-cavity, thermally matched construction delivers stable RF performance under pulsed and CW conditions up to 20 W in stud packages.

As a discrete PIN diode, it operates in variable-resistance mode under forward bias (10 μA–100 mA) and high-impedance switch mode under reverse bias (≤200 V). Its parallel resistance exceeds 150 kΩ at 100 V/100 MHz, ensuring minimal RF leakage in shunt-switch configurations.

Key Specifications

Pinout & Package

UM7301B is supplied in Style 'B' package: axial-leaded, non-isolated, stud-mountable metal-can housing with ½-inch total lead length. Thermal path relies on direct lead conduction to PCB or heatsink.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF switching and attenuator applications.

Compared with UM7301B, UM7301C offers electrical isolation but lower power handling (7.5 W vs. 15 W), while UMX7301B matches all electrical behavior but adds RoHS compliance - making UM7301B optimal for legacy non-RoHS industrial RF subsystems needing maximum thermal efficiency in Style B layout.

Availability

UM7301B is available at Aetrix Electronics and suitable for HF/VHF linear attenuators, T/R switches for SDR transceivers, and UHF broadcast signal routing requiring stable component supply and long-lifecycle support.

Supply support for UM7301B 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, timing, and power management solutions for aerospace, defense, and industrial markets.

The UM7300 series was developed specifically for high-linearity, high-voltage RF control in military comms, broadcast infrastructure, and test instrumentation - emphasizing low distortion, thermal stability, and rugged packaging.

FAQ

What is the maximum RF voltage the UM7301B can block in reverse bias?

The UM7301B is rated for 200 V reverse voltage at 10 μA leakage current. This allows it to block RF signals with peak voltages up to ±200 V in T/R switch or limiter applications. Operation beyond this rating risks irreversible breakdown. The 200 V rating is validated per Microsemi's absolute maximum specifications and applies across the full HF–1 GHz operating band when mounted per Style B thermal guidelines.

Does the UM7301B require a heatsink in continuous 10 W operation?

Yes - in continuous 10 W operation, the UM7301B (Style B) requires a thermal path to maintain junction temperature within safe limits. With θ_JA = 4 °C/W, a 10 W load generates a 40 °C rise above ambient. Mounting the leads to a copper pour or heatsink is recommended for ambient temperatures exceeding 40 °C. Derating curves on page 3 confirm 15 W max at 25 °C lead temperature.

Can the UM7301B be used in surface-mount designs?

No - UM7301B is a Style B axial-leaded metal-can package intended for through-hole or stud mounting. Surface-mount variants exist in the same family (e.g., UM7301SM), but UM7301B itself lacks solder pads or gull-wing leads. Attempting reflow or hand-soldering UM7301B risks thermal damage to the die and voids the specified 0.7 pF capacitance and 3.0 Ω R_S.

How does carrier lifetime affect distortion performance in UM7301B-based attenuators?

The UM7301B's minimum 4.0 μs carrier lifetime directly determines third-order intercept point (IP3) in linear attenuators. Longer lifetimes suppress intermodulation by maintaining uniform carrier density during RF signal zero-crossings. At 4.0 μs, UM7301B achieves IMD3 < −80 dBc at 20 W PEP - critical for multi-tone HF communications where spectral regrowth must stay below −70 dBc per FCC/ETSI masks.

Is there a drop-in replacement for UM7301B with improved thermal performance?

No - UM7301B has no pin-compatible thermal upgrade. UM7301C offers electrical isolation but higher thermal resistance (20 °C/W), while UM7301D provides 25 °C/W. For better thermal performance, redesign to Style A (7.5 °C/W) or Style C with forced-air cooling is required. UM7301B remains optimal for cost-sensitive, space-constrained Style B layouts where 4 °C/W meets thermal budget.