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Details, datasheet, quote on part number:NCO8205
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Datasheet text preview:
APPLICATION NOTE
A wide-band class-AB hybrid coupled amplifier (470 - 860 MHz) with two balanced transistors BLV57
NCO8205
Philips Semiconductors
A wide-band class-AB hybrid coupled amplifier Application Note (470 - 860 MHz) with two balanced transistors BLV57 NCO8205
CONTENTS 1 2 3 3.1 3.2 3.3 3.4 3.5 4 4.1 4.2 5 SUMMARY INTRODUCTION DESIGN OF THE AMPLIFIER General remarks Bias circuit Some properties of the BLV57 Input and output circuit Hybrid coupled amplifier MEASURED PERFORMANCE Gain and return losses Output power CONCLUSION
1998 Mar 23
2
Philips Semiconductors
A wide-band class-AB hybrid coupled amplifier (470 - 860 MHz) with two balanced transistors BLV57
1 SUMMARY
Application Note NCO8205
For application in TV transmitters in band 4/5 a wideband linear power amplifier has been designed with two balanced transistors BLV57 in a class AB DC-setting (VCE = 25 V and ICZ = 2 × 100 mA). A class A amplifier designed around the BLV57 has been described in reports NCO8101 and NCO8201. The results of the class AB input and output circuit calculations are about similar to the results of the class A application. Therefore the p.c.-board design of the class A-amplifier can be used. The applied circuit board is a double copper clad PFTE fibre-glass print with an r = 2.74 and a thickness of 1/32 inch. The heatsink has a forced air cooling. The main results are given in Table 1. Table 1 DC-setting Gain at Pout = 5 W Pout at 1 dB gain compression Efficiency at 1 dB gain compression 2 INTRODUCTION ICZ = 4 × 100 mA, VCE = 25 V 6 dB 42.5 W 45%
The BLV57 is a balanced transistor in an 8 lead envelope (SOT161) for class A operation in TV-transposers for band 4/5. A class A amplifier, designed around two transistors BLV57, has been described in report NCO8101 and the construction of this amplifier in report NCO8201. Because there is also a typical class AB specification a wide-band power amplifier has been designed around two transistors BLV57 in class AB. The quiescent current ICZ = 100 mA per chip and the VCE = 25 V. 3 3.1 DESIGN OF THE AMPLIFIER General remarks
The schematic line-up of the complete amplifier is given in Fig.1.
1998 Mar 23
3
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