NXP Semiconductors MRF9085LR5

Overview

MRF9085LR5 from NXP Semiconductors (formerly Freescale) is an N-channel enhancement-mode lateral RF power MOSFET designed for broadband common-source amplifier applications in 26 V base station equipment operating from 865 to 895 MHz. It delivers 90 W PEP output power, 17.9 dB two-tone power gain, and 40% drain efficiency at 865 MHz with 700 mA quiescent drain current.

For engineers reviewing the MRF9085LR5 datasheet, MRF9085LR5 pinout, MRF9085LR5 application, or MRF9085LR5 equivalent, this device is selected for high-linearity, high-efficiency RF power amplification in IS-95 CDMA infrastructure where VSWR tolerance, thermal stability, and internally matched input/output are critical design requirements.

Technical Context

This device operates as a Class AB RF power amplifier with internally matched 50 Ω input and output impedance optimized for 865–895 MHz. Its lateral MOSFET architecture enables high gain (17.9 dB), low IMD (−31 dBc third-order), and robust 10:1 VSWR survivability at 90 W CW output under 26 V DC bias.

Thermal performance is defined by a 0.7 °C/W junction-to-case thermal resistance and 200 °C maximum junction temperature. Gate threshold voltage is 2.0–4.0 V, with typical gate quiescent voltage of 3.7 V at 700 mA IDQ - enabling stable biasing in fixed-gate-voltage or active bias networks.

Key Specifications

Pinout & Package

Package: NI-780 (Case 465-06, Style 1), hermetically sealed ceramic/metal flange package with integral heatsink tab. Dimensions: 34.16 mm × 9.91 mm × 4.32 mm (L×W×H), flange-mount compatible.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF power transistor applications.

Compared with MRF9085LR5, MRF9085LSR3 offers identical RF performance in a smaller NI-780S package, while PD57018-E extends frequency coverage and output capability at the expense of proven VSWR resilience and CDMA-optimized linearity - making MRF9085LR5 the preferred choice for 865–895 MHz IS-95 infrastructure where reliability under mismatch is mandatory.

Availability

MRF9085LR5 is available at Aetrix Electronics and suitable for CDMA base station power amplifiers, public safety repeaters, ISM band infrastructure, and land mobile radio exciters requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for MRF9085LR5 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

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and communication infrastructure markets.

The MRF9085LR5 belongs to NXP's legacy RF Power Transistor family, originally developed by Freescale for high-reliability, high-efficiency cellular infrastructure amplifiers operating in the 800–900 MHz bands.

FAQ

What is the maximum continuous drain current rating for the MRF9085LR5?

The MRF9085LR5 does not specify a maximum continuous drain current (ID) rating. Instead, its safe operating area is defined by total device dissipation (250 W at TC = 25°C, derated 1.43 W/°C above), junction temperature limit (200 °C), and case temperature limit (150 °C). Typical operating IDQ is 700 mA, but peak pulsed current depends on duty cycle and thermal management. Always refer to the SOA curve in the MRF9085 datasheet Rev. 11 for validated limits.

Does the MRF9085LR5 require external input matching networks?

No, the MRF9085LR5 is internally matched for 50 Ω operation across 865–895 MHz, eliminating the need for external input matching networks in standard configurations. The datasheet confirms internal input matching in Table 4 footnote and Figure 1 schematic, where only output matching components (Z11–Z16) are shown. However, fine-tuning may be needed for specific load conditions or harmonic suppression.

What is the gate threshold voltage range for the MRF9085LR5?

The MRF9085LR5 has a gate threshold voltage (VGS(th)) range of 2.0 V to 4.0 V, measured at VDS = 10 Vdc and ID = 300 μAdc. This parameter defines the minimum gate voltage required to begin channel conduction. For stable Class AB operation, the typical gate quiescent voltage (VGS(Q)) is 3.7 V at VDS = 26 Vdc and IDQ = 700 mA - a value used in bias network design to set operating point.

Can the MRF9085LR5 be used in 900 MHz GSM applications?

The MRF9085LR5 is characterized and optimized for 865–895 MHz operation, with published performance data (gain, efficiency, IMD) only within that band. While it may function near 900 MHz, Freescale's datasheet does not validate parameters at 900 MHz - notably, the 960 MHz P1dB value is derived from a different test fixture and explicitly noted as "not applicable" to Figures 1 and 2. Use in GSM requires full characterization at 900 MHz.

What is the thermal resistance from junction to case for the MRF9085LR5?

The MRF9085LR5 has a thermal resistance of 0.7 °C/W from junction to case (RθJC), as specified in Table 2 of the datasheet. This value assumes proper mounting to a flat, smooth heatsink with recommended thermal interface material and torque. Effective thermal design must also account for heatsink-to-ambient resistance to maintain TJ ≤ 200 °C under full 90 W PEP load.