Capable of wide power range control as encountered in UHF cellular telephone applications.· 440 MHz· 470 MHz· Specified 12.5 Volt, UHF Characteristics Output Power = 20 Watts Minimum Gain 21 dB Harmonics 40 dB (Max)· 50 Input/Output Impedance· Guaranteed Stability and Ruggedness· Epoxy Glass PCB Construction Gives Consistent Performance and Reliability· Circuit board photomaster available upon request by contacting RF Tactical Marketing in Phoenix, AZ.
Rating DC Supply Voltages RF Input Power RF Output Power 12.5 V) Operating Case Temperature Range Storage Temperature Range MHW720A1, MHW720A2 Symbol Vs1, Vs2 Pin Pout TC Tstg Value to +100 Unit Vdc W °C
ELECTRICAL CHARACTERISTICS (Vs1 and Vs2 set at 12.5 Vdc, 50 W system unless otherwise noted)
Characteristic Frequency Range Input Power (Pout 20 W) Power Gain (Pout 20 W) Efficiency (Pout 20 W) Harmonics (Pout 20 W, Reference) Input Impedance (Pout 50 W Reference) Gain Degradation (1) (Pout 20 W, Reference Gain MHW720A1 MHW720A2 Symbol Pin Gp Min Max No degradation in Pout All spurious outputs more than 60 dB below desired signal 200 mA Unit MHz % dB VSWR dB
Load Mismatch (VSWR = 15.5 Vdc, Pout 30 W) Stability (Pin to 250 mW, to 15.5 Vdc) MHW720A2 1. Load VSWR 50 W Reference 2. Source VSWR 50 W Refernece Quiescent Current No RF Drive Applied) MHW720A1, MHW720A2
NOTE: 1. See Figure 5, Input Power versus Case Temperature
Nominal Operation All electrical specifications are based on the nominal conditions of Vs1 (Pin 5) and Vs2 (Pin 3) equal to 12.5 Vdc and with output power equaling 20 watts. With these conditions, maximum current density on any device 105 A/cm2 and maximum die temperature with 100° base plate temperature is 165°. While the modules are designed to have excess gain margin with ruggedness, operation of these units outside the limits of published specifications is not recommended unless prior communications regarding intended use has been made with the factory representative. Gain Control This module is designed for wide range Pout level control. The recommended method of power output control, as shown in Figure is to fix Vs1 and at 12.5 Vdc and vary the input RF drive level at Pin 7. In all applications, the module output power should be limited to 20 watts. passed with 0.018 µF chip capacitor effective for frequencies from 5 through 470 MHz. For bypassing frequencies below 5 MHz, networks equivalent to that shown in the test fixture schematic are recommended. Inadequate decoupling will result in spurious outputs at certain operating frequencies and certain phase angles of input and output VSWR less than 4:1. Load Mismatch During final test, each module is load mismatch tested in a fixture having the identical decoupling network described in Figure 1. Electrical conditions are Vs1 and Vs2 equal 15.5 V, load VSWR infinite, and output power equal to 30 watts. Mounting Considerations To insure optimum heat transfer from the flange to heatsink, use standard 632 mounting screws and an adequate quantity of silicon thermal compound (e.g., Dow Corning 340). With both mounting screws finger tight, alternately torque down the screws to 46 inch pounds. The heatsink mounting surface directly beneath the module flange should be flat to within 0.005 inch to prevent fracturing of ceramic substrate material. For more information on module mounting, see EB107.
Decoupling Due to the high gain of the three stages and the module size limitation, the external decoupling network requires careful consideration. Both Pins 3 and 5 are internally by-
C7 50 Ohm Load MHW720A Text Fixture Schematic 0.1 µF Ceramic 47 µF Tantalum, 25 V
NOTE: No Internal D.C. blocking on input pin.
Figure 2. Input Power, Efficiency, and VSWR versus Frequency
Figure 3. Output Power versus Input Power
Figure 5. Input Power versus Case Temperature
Figure 6. Output Power versus Case Temperature 10.8 V Supply