Digital logic circuits for producing digital sum and difference frequencies
AssigneeGTE Automatic Electric Laboratories Incorporated
InventorLawrence E. Getgen
Life of this patent
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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.
Claims22
Apparatus for obtaining a signal having a frequency component equal to the algebraic sum of the fundamental frequencies of a pair of logic signals, A(t) and B(t), comprising:
- means for deriving the complement of the true form of at least one of said pair of logic signals, whereby true and complementary forms of the signal are available;
- combining means, including means for logically combining in selected pairs true and complementary forms of said pair of logic signals, the combining means providing at its output the sum and difference of the fundamental frequencies of said logic signals in digital form;
- and
- selecting means having an output, and having an input connected to the output of the combining means, said selecting means providing at its output either the sum or the difference frequency.
A method for obtaining a frequency equal to the sum or difference frequency of a pair of logic signals, A(t) and B(t), consisting of the steps of:
- deriving the complement of the true form of at least one of the pair of logic signals;
- combining selected pairs of the true and complementary forms of said pairs of logic signals to obtain the sum and difference frequencies in digital form;
- and
- selecting the sum or difference frequency.
Apparatus for obtaining a signal having a frequency equal to the algebraic sum of a pair of logic signals comprising:
- means for obtaining the true and complementary forms of one of said signals,
- a first logic circuit having an input connected to receive the true form of said one signal and having another input connected to receive the other of said pair of signals, and providing an output having a logical 1 in all cases except when said true form and said other signal are both a logical 1;
- a second logic circuit having an input connected to receive said complementary form signal and having another input connected to receive said other signal and providing an output having a logical 1 in all cases except when said complementary and said other signal are both a logical 1;
- and,
- means summing said outputs.
Apparatus for obtaining the product of a pair of first and second signals alternating between bipolar logic levels comprising:
- means for obtaining the true and complementary forms of said first and second signals;
- a first logic circuit connected to said true forms of said first and second signals and providing a first output having a logical 1 in all cases except when said true form signals are a logical 1;
- a second logic circuit connected to said complementary forms of said first and second signals and providing a second output having a logical 1 in all cases except when said complementary signals are a logical 1;
- and,
- a third logic circuit connected to said first and second outputs and providing an output having a logical 1 in all cases except when said first and second outputs are a logical 1.
Dependencies are inferred from the claim text.