Balanced-to-unbalanced converting circuit

Abstract

A balanced-to-unbalanced converting circuit in which balanced-to-unbalanced converters are formed by a stripline in such a manner as to include a copper foil pattern which is formed on an inner or surface printed circuit layer of a multi-layer substrate and are connected to a double balanced mixer serving as a surface-mounted component provided on a first printed circuit. In the case of this converting circuit, a part of conventional surface-mounted components are eliminated from the multi-layer substrate. Thereby, the high density packaging of other surface-mounted components can be achieved. This contributes to the miniaturization, thickness reduction, weight reduction and price reduction of an entire portable telephone. Further, the balanced-to-unbalanced converters are formed by placing the copper foil pattern on a printed circuit layer which is sandwiched between grounded conductor layers of the multi-layer substrate. Thereby, the electrical connection between the balanced-to-unbalanced converters and the interference therebetween can be reduced. Consequently, the performance of the circuit can be improved.

Dependencies are inferred from the claim text.