ECO7213 Datasheet | Philips Semiconductors

APPLICATION NOTE Design of H.F. Wideband Power Transformers; Part II ECO7213 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 Design of H.F. Wideband Power Transformers; Part II CONTENTS 1 2 3 4 5 6 7 SUMMARY INTRODUCTION L.F. LIMITATIONS OF CONVENTIONAL TRANSFORMERS H.F. LIMITATION OF CONVENTIONAL TRANSFORMERS H.F. PENSATION OF CONVENTIONAL TRANSFORMERS A PRACTICAL EXAMPLE REFERENCES 1998 Mar 23 Philips Semiconductors Design of H.F. Wideband Power Transformers; Part II 1 SUMMARY In part I of this report (ECO6907) the transmission line transformer has been discussed extensively. In this second part attention has been paid to the conventional transformer as a wideband matching element in e.g. S.S.B. transmitters. The main problem in these transformers is stray-inductance. Some H.F. pensation methods are discussed and a design example is given. 2 INTRODUCTION Report ECO6907 (Ref. 1) has been devoted entirely to the design of transmission line transformers. This type of transformer has undoubtedly the advantage of the largest possible bandwidth. However it has also some drawbacks: 1. The impedance transformation ratio is restricted to (n : m)2 in which n and m are small integers 2. They are difficult to construct when a number of windings must be bined. Therefore it is certainly worthwhile to consider the possibility of applying a conventional transformer if the abovementioned problems arise. 3 L.F. LIMITATIONS OF CONVENTIONAL TRANSFORMERS These limitations are the same as for transmission line transformers, viz. parallel inductance and maximum flux density. They have been described in the abovementioned reports including pensation methods for the parallel inductance. 4 H.F. LIMITATION OF CONVENTIONAL TRANSFORMERS The most important property that limits the H.F. performance of a conventional transformer is the well-known stray-inductance. The equivalent circuit of the...