Microchip Technology UM9604

Overview

UM9604 from Microsemi is a hermetically sealed, low-inductance shunt-mount PIN diode optimized for microstrip antenna switches at 900 MHz, with 0.25 dB insertion loss at 1.0 GHz (100 mA bias), 32 dB isolation at 1.0 GHz (100 mA bias), and 100 V reverse voltage rating. It affixes to microstrip backing plates and supports high-power RF switching in base station transceivers.

For engineers reviewing the UM9604 datasheet, UM9604 pinout, UM9604 application, or UM9604 equivalent, key selection criteria include its 0.6 Ω typical series resistance at 100 mA/100 MHz, 150 kΩ parallel resistance at 100 V, 1.2 pF total capacitance, 80–150 µm I-region width, and thermal resistance <20 °C/W when solder-mounted - all critical for UHF-to-4 GHz SPST switch design.

Technical Context

The UM9604 is engineered as a discrete shunt-switch element for microstrip transmission lines, using fused-in-glass packaging with symmetrical full-faced metallurgical bonds to minimize parasitic inductance and capacitance. Its I-region width (80–150 µm) and carrier lifetime (2.0 µs) are tuned for high-isolation, low-distortion operation up to 4 GHz.

It operates in forward-biased (low-Rs) and reverse-biased (high-Rp) states to enable SPST switching in quarter-wave antenna circuits. Performance is characterized on 0.025" alumina microstrip with SMA connectors, where measured isolation reaches 32 dB at 1.0 GHz under 100 mA bias - including board and connector losses.

Key Specifications

Pinout & Package

UM9604 uses a cup-type flange package designed for direct solder mounting to microstrip backing plates. The device has two terminals: anode and cathode, with the cup flange serving as the cathode connection point. Mechanical drawings confirm a 0.125" (3.18 mm) diameter cup flange with 0.062" (1.57 mm) height and center-mounted anode post.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PIN diode shunt-switch applications.

Compared with UM9602 and SMP1320-079, UM9604 uniquely balances 100 V reverse rating, sub-0.7 Ω series resistance, and flange-mount thermal performance - making it the optimal choice for solder-mounted 900 MHz antenna switches demanding >30 dB isolation and 100 W infinite-SWR capability.

Availability

UM9604 is available at Aetrix Electronics and suitable for cellular infrastructure, land mobile radio, ISM band radios, and avionics RF systems requiring stable component supply across extended temperature and high-reliability environments.

Supply support for UM9604 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 aerospace, defense, and communications markets.

The UM9601–UM9608 series was developed specifically for microstrip-based RF switching in UHF-to-4 GHz systems, emphasizing ruggedized packaging, low parasitic inductance, and repeatable high-power performance in field-deployed transceivers.

FAQ

What is the maximum continuous RF power UM9604 can handle in a microstrip antenna switch?

UM9604 supports 100 W transmitter power at infinite SWR in a validated 900 MHz quarter-wave antenna switch configuration when forward-biased at 100 mA and operated at 60 °C ambient. This rating assumes proper thermal coupling to a metal backing plate achieving <20 °C/W junction-to-heatsink resistance, as confirmed in Microsemi's application note on UM9601–UM9608 thermal characterization.

How does UM9604 differ from UM9601 in terms of mounting and RF performance?

UM9604 and UM9601 share identical electrical specs and cup-flange packaging, but UM9604 is designated for mounting to microstrip backing plates (mechanical drawing Page 11), whereas UM9601 mounts to the ground plane surface. Both deliver 0.25 dB insertion loss and 32 dB isolation at 1.0 GHz under 100 mA bias - however, UM9604's backing-plate orientation optimizes thermal path in high-power stacked-board assemblies.

Is UM9604 RoHS compliant?

UM9604 itself is not RoHS compliant in its standard configuration; Microsemi offers RoHS-compliant variants under the UMX960x prefix (e.g., UMX9604). The standard UM9604 contains leaded glass seal and lead-tin solder-compatible plating - verified in the "RoHS compliant packaging available" footnote on Page 1 of the datasheet.

What is the typical third-order intermodulation distortion (IMD3) of UM9604 in receiver mode?

In reverse-bias (zero-current) receiver mode, UM9604 exhibits ≥100 dBc third-order intermodulation distortion for two 0 dBm in-band signals - measured at 43/44 MHz and 7.4/7.6 MHz per Figure 7 on Page 6 of the datasheet. This low distortion preserves adjacent-channel selectivity in dense RF environments without additional filtering.

Can UM9604 be used in multi-throw switch topologies?

Yes - UM9604 is qualified for multi-throw microstrip switches when placed λ/4 from the common port, as stated on Page 9. In such configurations, isolation improves by 6 dB over SPST measurements (e.g., 32 dB → 38 dB), and dual-shunt arrangements further double isolation - provided substrate thickness and dielectric constant match the 0.025" alumina reference design.