ECO7904 Datasheet | Philips Semiconductors

APPLICATION NOTE A wide-band class-A linear power amplifier (174 - 230 MHz) with two transistors BLV33 ECO7904 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 two transistors BLV33 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 ECO7904 1998 Mar 23 Philips Semiconductors A wide-band class-A linear power amplifier (174 - 230 MHz) with two transistors BLV33 1 ABSTRACT Application Note ECO7904 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 BLV33, 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 - 56 and - 58 d B. At this power level the cross-modulation varied from 6 to 7.5%. The power gain is between 8.35 and 8.6 d B. 2 INTRODUCTION For application in T.V. transposers and transmitters for band III a wideband linear power amplifier has been designed with 2 transistors BLV33, 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. 3 DESIGN OF THE AMPLIFIER For class-A operation the BLV33 is specified at VCE = 25 V, IC = 3.25 A. The corresponding typical gain, input and load impedance are given below: Table 1 FREQ. (MHz) 174 202 230 GAIN (d B) 11.3 10.1 9.08 INPUT IMPEDANCE (Ω) 0.68 + j1.20 0.68 + j1.43 0.68 + j1.64 LOAD IMPEDANCE (Ω) 2.70 + j1.19 2.30 + j0.87 1.99 + j0.52 A puter-aided circuit design, carried out by Mr. Hilbers (Central Application Laboratory) indicated a gain of 9.1 d B ±0.1 d B and V.S.W.R. figures of 4.3 (170 MHz), 2.78 (202 MHz) and 1.18 at 230...