ECO8005 Datasheet | Philips Semiconductors

APPLICATION NOTE A wide-band class-A linear power amplifier (174 - 230 MHz) with 2 transistors BLV33F ECO8005 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 class-A linear power amplifier (174 - 230 MHz) with 2 transistors BLV33F CONTENTS 1 2 3 4 5 6 7 8 ABSTRACT INTRODUCTION DESIGN OF THE AMPLIFIER ADJUSTMENTS OF THE AMPLIFIER ASSEMBLING OF THE AMPLIFIER AND MECHANICAL DATA MEASURED RESULTS CONCLUSION REFERENCES Application Note ECO8005 1998 Mar 23 Philips Semiconductors A wide-band class-A linear power amplifier (174 - 230 MHz) with 2 transistors BLV33F 1 ABSTRACT Application Note ECO8005 For application in driver or final stages of TV-transposers in Band III (174-230 MHz) a linear wideband power amplifier has been designed with 2 transistors BLV33F, coupled by means of 3 d B - 90° hybrids. Each transistor is adjusted in Class-A at VCE = 25 V and IC = 3.25 A. A demonstration model showed a peak sync. output power of 40 W at a 3-tone I.M. distortion between - 52 and - 53 d B. At this power level the cross-modulation varied from 15 to 18%. The power gain is between 13.3 and 13.6 d B. For natural convection cooling the heatsink temperature is 40 °C above ambient temperature. 2 INTRODUCTION For application in T.V. transposers and transmitters for Band III a wideband linear power amplifier has been designed with 2 transistors BLV33F, coupled by means of 3 d B - 90° hybrids. Each transistor is adjusted in Class-A at VCE = 25 V and IC = 3.25 A. Note: The BLV33F is a high gain, internally matched, 1/2 inch 6 leads flange version of the BLV33. 3 DESIGN OF THE AMPLIFIER For class-A operation the BLV33F is specified at VCE = 25 V, IC = 3.25 A. The corresponding typical gain, input and load impedance are given in Table 1: Table 1 FREQ. (MHz) 174 202 230 GAIN (d B) 12.94 12.88 13.91 INPUT IMPEDANCE (Ω) 0.85 + j0.59 1.02 + j0.47 0.93 + j0.02 LOAD IMPEDANCE (Ω) 2.68 + j1.24 2.23 + j0.90 1.84 +...