ECO7901 Datasheet | Philips Semiconductors

APPLICATION NOTE A wide-band linear power amplifier (470 - 860 MHz) with two transistors BLW34 ECO7901 w w w t a .D S a e h U 4 t e .c m o w w w .D a S a t e e h U 4 t m o .c Philips Semiconductors A wide-band linear power amplifier (470 - 860 MHz) with two transistors BLW34 CONTENTS 1 2 3 3.1 3.1.1 3.1.2 4 4.1 4.2 4.3 5 6 ABSTRACT INTRODUCTION THEORETICAL CONSIDERATIONS The equivalent circuit of the BLW34 The output network The input network THE HYBRID COUPLED AMPLIFIER Practical considerations Practical optimization Intermodulation, VSWR and gain measurements CONCLUSIONS REFERENCES Application Note ECO7901 1998 Mar 23 Philips Semiconductors A wide-band linear power amplifier (470 - 860 MHz) with two transistors BLW34 1 ABSTRACT Application Note ECO7901 For application in driver or final stages of TV-transposers in band IV/V (470-860 MHz) a linear wideband power amplifier has been designed with 2 transistors BLW34 coupled by means of 3 d B - 90° hybrids. Each transistor is adjusted in class-A at VCE = 25 V and Ic = 0.6 A. The peak sync output power for a 3-tone I.M. distortion of - 60d B varies between 3.6 and 5.4 W. The power gain is 9.1 ± 0.3 d B. Input and output VSWR are below 1.3. 2 INTRODUCTION This report describes the realisation of a wide-band UHF power amplifier for TV transposer service in band IV and V (470 - 860 MHz). The amplifier is designed with the BLW34 transistor being developed for ultra linear applications operating in class A. Each device is able to deliver at least 1.8 W peak sync output. The BLW34 forms a series with the smaller devices BLW33 (1.0 W) and BLW32 (0.5 W). The power gain at 860 MHz is at least 9 d B. The BLW34 is encapsulated in a 1/4 inch capstan envelope with ceramic cap. 3 3.1 THEORETICAL CONSIDERATIONS The equivalent circuit of the BLW34 For class A operation the BLW34 is specified at VCE = 25 V; Ic = 600 m A. The corresponding typical gain, input and load impedance according to the Data sheets are...