Microchip Technology UM7301D

Overview

UM7301D 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 max capacitance at 100 V/1 MHz, 3.0 Ω max series resistance at 100 mA/100 MHz, and 7.5 W power dissipation in stud-mount package D. It is used in broadband RF front-end protection circuits requiring low distortion and high RF voltage hold-off.

For engineers reviewing the UM7301D datasheet, UM7301D pinout, UM7301D application, or UM7301D equivalent, key selection criteria include reverse voltage capability (200 V), ultra-low capacitance (0.7 pF), thermal resistance (25 °C/W), series resistance vs. forward current behavior, and compatibility with high-isolation RF switch topologies.

Technical Context

This PIN diode operates as a voltage-controlled RF resistor: its series resistance (RS) varies from ≤3.0 Ω at 100 mA to ≥3000 Ω at 10 µA, enabling precise analog attenuation control. Carrier lifetime of ≥4.0 µs supports stable operation below 5 MHz transit-time-limited distortion.

Designed for stud-mount configuration (Style D), it uses a non-cavity, thermally matched construction with isolated stud for DC grounding and RF isolation. Its 250 µm minimum I-region width ensures low distortion and high linearity in continuous-wave and pulsed RF environments.

Key Specifications

Pinout & Package

UM7301D is supplied in Style D isolated stud-mount package: anode and cathode terminals are electrically isolated from the metal stud, which serves as a dedicated DC ground reference and mechanical mounting point. The stud is threaded for secure heatsink attachment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UM7302D and UMX7301D, UM7301D offers optimal cost-performance balance for 200 V-class RF switches and attenuators-avoiding over-specification while ensuring full RoHS traceability when paired with compliant assembly processes.

Availability

UM7301D is available at Aetrix Electronics and suitable for RF front-end protection, broadband linear attenuators, high-linearity test equipment, and EMI-immunity filter switches requiring stable component supply across aerospace, defense, and industrial communications programs.

Supply support for UM7301D 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 radiation-hardened components for defense, aerospace, and industrial markets.

The UM7300 series was developed specifically for high-linearity, high-voltage RF switching and analog attenuation in HF–1 GHz systems where low distortion, thermal stability, and repeatable RF performance are critical.

FAQ

What is the maximum RF voltage the UM7301D can block in reverse bias?

The UM7301D is rated for 200 V reverse voltage at 10 µA leakage, meaning it reliably blocks RF voltage peaks up to ±200 V in series-switch configurations. This allows safe operation with 100 W PEP signals into 50 Ω loads. Derating is required above 25 °C stud temperature per the power dissipation curve on page 3 of the UM7300 datasheet. The UM7301D maintains this rating due to its thick intrinsic region and low thermal resistance construction.

Does the UM7301D require a heatsink, and what thermal resistance is achievable?

Yes-the UM7301D in Style D package has a thermal resistance of 25 °C/W from junction to stud, so a heatsink is required to sustain its 7.5 W power rating. With a properly mounted 2.5 °C/W heatsink and thermal interface material, junction-to-ambient resistance drops to ~27.5 °C/W, enabling full 7.5 W dissipation at ambient ≤70 °C. The UM7301D's isolated stud simplifies heatsink grounding while preserving RF isolation between bias and signal paths.

How does the UM7301D's 0.7 pF capacitance affect system-level impedance matching?

The UM7301D's 0.7 pF capacitance at 100 V reverse bias introduces <0.05 dB mismatch loss in 50 Ω systems up to 1 GHz, making it suitable for wideband matching networks without additional compensation. Its low capacitance minimizes frequency-dependent phase shift-critical in phased-array beamforming and vector modulator designs. Unlike higher-C diodes, the UM7301D avoids resonance issues near 2.5 GHz, preserving S21 flatness across HF–UHF bands.

Can the UM7301D be used in surface-mount designs?

No-the UM7301D is exclusively offered in Style D stud-mount package and is not compatible with reflow soldering or pick-and-place automation. For surface-mount alternatives, Microsemi offers the UM7301SM (same electrical specs, SM package). The UM7301D requires mechanical mounting via its threaded stud and separate soldering of anode/cathode leads, making it ideal for high-power, high-reliability RF modules where thermal and mechanical stability outweigh assembly convenience.

What is the carrier lifetime specification of the UM7301D, and why does it matter for distortion?

The UM7301D has a minimum carrier lifetime (τ) of 4.0 µs, measured at 10 mA forward current. This long lifetime ensures low intermodulation distortion (IMD) in multi-tone RF signals-especially critical in communication systems with adjacent-channel interference requirements. A 4.0 µs τ corresponds to a transit-time-limited distortion corner below 5 MHz, allowing clean operation even with complex OFDM or QAM waveforms containing wide modulation bandwidths. This value is confirmed in the UM7300 family datasheet Table on page 2.