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Details, datasheet, quote on part number:NCO8704
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APPLICATION NOTE
Linear performance of BLF244 in S.S.B. class-A operation
NCO8704
Philips Semiconductors
Linear performance of BLF244 in S.S.B. class-A operation
CONTENTS 1 2 3 4 5 INTRODUCTION TESTCIRCUIT TESTCONDITIONS TESTRESULTS CONCLUSION
Application Note NCO8704
1998 Mar 23
2
Philips Semiconductors
Linear performance of BLF244 in S.S.B. class-A operation
1 INTRODUCTION
Application Note NCO8704
This report contains results of measurements carried out on the BLF244 in S.S.B. Class-A operation. Linear measurements have been performed on six transistors from batch R150C (ass. nr. 3030). Each transistor was taken from a different slice. 2 TESTCIRCUIT
Measurements have been done in a wideband amplifier designed for the frequency range 1.6 - 28 MHz. The circuit diagram and component list are given in Fig.6 and Table 1. Negative feedback (R2) has been employed to attain a flat gain of the amplifier. A shunt resistor (R1) between gate and source takes care of stable operation and also decreases the input resistance to 12.5 . Matching to 50 is accomplished with a 4 : 1 broadband transformer. At the output side a broadband load of 50 is provided to the transistor. A more detailed description of this kind of amplifiers is given in application report NCO8705. 3 TESTCONDITIONS
The quiescent drain current for class-A operation is set to 0.6 A at a supply voltage of 28 V. This is below the maximum allowable DC-current for a heatsink temperature of 70 °C which is 0.9 A for this device. Linearity measurements have been performed with two tones of equal amplitude with a frequency seperation of 1 kHz. The intermodulation distortion products d3 and d5 are referred to the amplitude of one of the two tones. The transistors have been tested at a nominal output power of 4 W PEP, with a heatsink temperature of 25 °C. 4 TESTRESULTS
The table below contains results of measurements at f = 28 MHz of 6 devices. Conditions: Vds = 28 V; Idq = 0.6 A; Pout = 4 W PEP; Ths = 25 °C. Batch RI50C (ass.nr.3030) DEV.NO.-SLICENO. 2-2 18 - 3 27 - 10 32 - 12 44 - 19 52 - 21 PIN (mW) 9.0 9.0 8.8 8.9 8.8 8.8 GP (dB) 23.5 23.5 23.6 23.5 23.6 23.6 D3 (dB) -40.5 -41.0 -40.5 -40.5 -40.5 -40.5 D5 (dB) -60 -60 -60 -60 -60 -60 INPUT RET.LOSS (dB) -20.5 -22.0 -24.5 -22.5 -24.0 -23.0
Measurements have also been performed versus output power at f = 28 MHz. Figures 1 and 2 show the powergain and IMD (d3) of a typical device (dev.no.52 from slice 21). Pout is varied between 0.5 W and 8 W P.E.P which resulted in a gain variation of approximately 0.5 dB. IMD (d3) exceeds the level of -40 dB for an output power greater than 4.3 W PEP The amplifier performance versus frequency has also been measured at Pout = 4 W PEP with the same device. Figures 3, 4 and 5 show the powergain, IMD (d3) and input return loss versus frequency. The measuring frequency extends from 1.6 to 32 MHz. The resulted powergain is 24 dB ±0.4dB and IMD (d3) varies between -48 and -40.5 dB while the input return loss is better than -20 dB.
1998 Mar 23
3
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