Abstract: An inverter accepts the true form of a high-frequency signal at its input and provides the complement thereof at its output. The true form is applied to a first input of a first NAND-gate and the complementary form is applied to a first input of a second NAND-gate. A second signal, having a repetition rate which is set, for example, by the channel spacing required in an FDM carrier system, is applied to the second inputs of said first and second NAND-gates. The second signal is thereby alternately switched between the first and second output terminals of said NAND-gates at a rate equal to the frequency of the high-frequency signal. The first and second output terminals of said NAND-gates are connected to the first and second end terminals, respectively, of the primary winding of an output transformer. The end terminals of the secondary winding of said transformer are connected to the load or utilization device. The output signal comprises a spectrum having a sin x/x envelope centered at the high-frequency w.

Abstract: The present invention provides means for deriving a single frequency signal from logic signals A(t) and B(t) by first applying the logic signals to a combining arrangement, which includes logic circuits and can be built using only standard integrated circuit components, e.g., flip-flops, gates, and amplifiers. The output of the combining means is the sum and difference frequencies, in digital form, of the logic signals A(t) and B(t). The single frequency is selected from the frequencies present at the output of the combining means.