NXP Semiconductors MRF7S18125AHSR3

Overview

MRF7S18125AHSR3 from Freescale Semiconductor is an N-channel enhancement-mode lateral RF power MOSFET designed for GSM and GSM EDGE base station amplifiers operating at 1805–1880 MHz. It delivers 125 W CW output at 28 V, achieves 17 dB power gain and 55% drain efficiency in GSM mode, and supports Class AB/C operation under full cellular modulation schemes.

For engineers reviewing the MRF7S18125AHSR3 datasheet, MRF7S18125AHSR3 pinout, MRF7S18125AHSR3 application, or MRF7S18125AHSR3 equivalent, this device is selected for high-efficiency, high-power RF final-stage amplification in macrocell and remote radio head (RRH) transmitters where thermal robustness, spectral purity, and VSWR tolerance are critical.

Technical Context

This LDMOS transistor features internally matched input and output impedances optimized for 50 Ω systems across 1805–1880 MHz, with series-equivalent large-signal impedance characterization provided for design-in accuracy. Its gate threshold voltage (1.2–2.7 V) and quiescent gate voltage (2.7 V typ.) support stable Class AB biasing at 1100 mA IDQ.

The device operates at up to 225°C junction temperature and incorporates integrated ESD protection rated to Human Body Model Class 1B, Machine Model Class A, and CDM Class IV. Thermal resistance from junction to case is 0.34°C/W at 71 W CW, enabling reliable operation in forced-air or heatsink-cooled base station PA modules.

Key Specifications

Pinout & Package

Package: NI-780S (Case 465A-06, Style 1), flanged ceramic/metal hermetic package with solderable baseplate for direct thermal mounting. Dimensions: 20.45–20.70 mm × 9.65–9.91 mm × 4.32–5.33 mm (L×W×H).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MRF7S18125AHSR3, the MRFE6VP61K25HR5 offers extended bandwidth and higher P1dB but increases system-level design complexity due to missing on-die ESD and tighter gate bias tolerances, while the BLF8G22LS-125P trades hermetic ruggedness and VSWR tolerance for lower thermal resistance and lower cost in non-outdoor applications.

Availability

MRF7S18125AHSR3 is available at Aetrix Electronics and suitable for GSM macrocell transmitters, EDGE remote radio heads, and multi-carrier base station amplifiers requiring stable component supply, long-lifecycle support, and traceable sourcing for telecom infrastructure programs.

Supply support for MRF7S18125AHSR3 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

Freescale Semiconductor (now part of NXP Semiconductors) is a global leader in RF power solutions for wireless infrastructure, with deep expertise in LDMOS technology and base station amplifier design.

The MRF7S18125AHSR3 belongs to Freescale's MRF7S family of high-efficiency, high-reliability RF power MOSFETs engineered specifically for 2G/2.5G cellular base station final-stage amplification in the 1800–2000 MHz bands.

FAQ

What is the maximum continuous drain current rating for the MRF7S18125AHSR3?

The MRF7S18125AHSR3 does not specify a maximum continuous drain current (ID) rating independently; instead, its safe operating area is defined by maximum ratings including VDSS (−0.5/+65 V), VGS (−6.0/+10 V), and TJ (225°C). At typical operating conditions (VDD = 28 V, IDQ = 1100 mA), the device delivers 125 W CW output. Peak pulsed current capability is derived from P1dB (140 W) and thermal resistance (0.34°C/W), supporting transient loads within the SOA boundary defined in the datasheet.

Does the MRF7S18125AHSR3 require external matching networks for 1800 MHz band operation?

No - the MRF7S18125AHSR3 is internally matched for 50 Ω systems across 1805–1880 MHz, as confirmed by its characterized series-equivalent source and load impedances (e.g., Zsource = 1.18 − j2.66 Ω, Zload = 1.34 − j2.02 Ω at 1840 MHz). External matching is optional only for fine-tuning gain flatness or optimizing for specific VSWR or efficiency targets beyond the standard test circuit configuration.

What is the thermal resistance (RθJC) of the MRF7S18125AHSR3 at 71 W CW output?

The thermal resistance from junction to case (RθJC) for the MRF7S18125AHSR3 is 0.34°C/W when operating at 71 W CW with case temperature held at 80°C, as specified in Table 2 of the datasheet. This value is measured under controlled thermal test conditions using Freescale's methodology per AN1955 and reflects the device's ability to transfer heat from die to flange in real-world heatsink-mounted configurations.

Can the MRF7S18125AHSR3 be used in Class C amplifier configurations?

Yes - the MRF7S18125AHSR3 is explicitly characterized and qualified for both Class AB and Class C operation in GSM and GSM EDGE base station applications, as stated in the product summary. Its gate threshold voltage (1.2–2.7 V) and transconductance profile support efficient nonlinear switching behavior required for Class C, while maintaining stability and ruggedness under typical cellular modulations.

Is the MRF7S18125AHSR3 pin-compatible with the MRF7S18125AHR3?

Yes - both MRF7S18125AHSR3 and MRF7S18125AHR3 share identical pinout (Drain, Gate, Source) and electrical specifications, differing only in package: MRF7S18125AHSR3 uses NI-780S (Case 465A-06), while MRF7S18125AHR3 uses NI-780 (Case 465-06). The flange dimensions and terminal locations are mechanically aligned, enabling direct PCB footprint compatibility in most layouts.