MRF137 MACOM | Alldatasheet

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Technical content

/C0082 N–Channel Enhancement–Mode . . . designed for wideband large–signal output and driver stages up to 400 MHz range.

  • Guaranteed 28 Volt, 150 MHz Performance Output Power = 30 Watts Minimum Gain = 13 dB Efficiency — 60% (Typical)
  • Small–Signal and Large–Signal Characterization
  • Typical Performance at 400 MHz, 28 Vdc, 30 W Output = 7.7 dB Gain
  • 100% Tested For Load Mismatch At All Phase Angles With 30:1 VSWR
  • Low Noise Figure — 1.5 dB (Typ) at 1.0 A, 150 MHz
  • Excellent Thermal Stability, Ideally Suited For Class A Operation
  • Facilitates Manual Gain Control, ALC and Modulation Techniques MAXIMUM RATINGS Rating Symbol Value Unit Drain–Source Voltage VDSS 65 Vdc Drain–Gate Voltage (RGS = 1.0 MΩ ) VDGR 65 Vdc Gate–Source Voltage VGS ±40 Vdc Drain Current — Continuous ID 5.0 Adc Total Device Dissipation @ TC = 25°C Derate above 25°C PD 100 0.571 Watts W/°C Storage Temperature Range Tstg –65 to +150 °C Operating Junction Temperature TJ 200 °C THERMAL CHARACTERISTICS Characteristic Symbol Max Unit Thermal Resistance, Junction to Case R θJC 1.75 °C/W Handling and Packaging — MOS devices are susceptible to damage from electrostatic charge. Reasonable precautions in handling and packaging MOS devices should be observed. /C0077/C0082

30 W, to 400 MHz

N–CHANNEL MOS BROADBAND RF POWER FET CASE 211–07, STYLE 2 Order this document by MRF 137/DSEMICONDUCTOR TECHNICA L D ATA REV 6

Figure 1. 150 MHz Test Circuit

Table 1. Common Source Scattering Parameters

The MRF137 is a RF power N–Channel enhancement mode field–effect transistor (FET) designed especially for VHF power amplifier applications. M/A-COM RF MOS FE Ts feature a vertical structure with a planar design, thus avoiding the processing difficulties associated with V–groove vertical power FETs. M/A-COM Application Note AN211A, FETs in Theory and Practice, is suggested reading for those not familiar with the construction and characteristics of FETs. The major advantages of RF power FETs include high gain, low noise, simple bias systems, relative immunity from ther- mal runaway, and the ability to withstand severely mis- matched loads without suffering damage. Power output can be varied over a wide range with a low power dc control signal, thus facilitating manual gain control, ALC and modulation. DC BIAS The MRF137 is an enhancement mode FET and, therefore, does not conduct when drain voltage is applied. Drain current flows when a positive voltage is applied to the gate. See Figure 10 for a typical plot of drain current versus gate voltage. RF power FETs require forward bias for optimum performance. The value of quiescent drain current (I DQ ) is not critical for many applications. The MRF137 was characterized at IDQ = 25 mA, which is the suggested minimum value of IDQ . For special applications such as linear amplification, IDQ may have to be selected to optimize the critical parameters. The gate is a dc open circuit and draws no current. Therefore, the gate bias circuit may generally be just a simple resistive divider network. Some special applications may require a more elaborate bias system. GAIN CONTROL Power output of the MRF137 may be controlled from its rated value down to zero (negative gain) by varying the dc gate voltage. This feature facilitates the design of manual gain control, AGC/ALC and modulation systems. (See Figure 9.) AMPLIFIER DESIGN Impedance matching networks similar to those used with bi- polar VHF transistors are suitable for MRF137. See M/A-COM plied to RF Power Transistors. The higher input impedance of RF MOS FETs helps ease the task of broadband network de- sign. Both small signal scattering parameters and large signal impedances are provided. While the s–parameters will not produce an exact design solution for high power operation, they do yield a good first approximation. This is an additional advantage of RF MOS power FETs. RF power FETs are triode devices and, therefore, not unilateral. This, coupled with the very high gain of the MRF137, yields a device capable of self oscillation. Stability may be achieved by techniques such as drain loading, input shunt resistive loading, or output to input feedback. Two port parameter stability analysis with the MRF137 s–parameters provides a useful tool for selection of loading or feedback circuitry to assure stable operation. See M/A-COM Application Note AN215A for a discussion of two port network theory and stability. REV 6

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