Tracking oscillators

DETAILED DESCRIPTION The present invention provides two oscillators, both powered by the same power supply.
The output signal frequencies of said oscillators can be varied simultaneously over a wide range.
The frequency difference between said output signals can be adjusted independently from 0 to a relatively large value, and said frequency difference will be maintained as the output signal frequencies of said oscillators are varied.
Furthermore, said frequency difference is stable over long periods of time.
Each of the oscillators provided by the present invention is a current controlled oscillator whose frequency of oscillation is directly proportional to an electrical current called the timing current.
Said frequency of oscillation is inversely proportional to the value of a capacitor called the timing capacitor.
The present invention is comprised of two such oscillators, a precision current mirror which causes at least a portion of the timing currents of said oscillators to track accurately, a variable resistance means which provides adjustment of the currents in the current mirror, and a variable resistance means which provides adjustment of an additional timing current to only one of the oscillators thereby providing means of adjusting the frequency difference.
While the aforementioned application required audio frequency sine waves, the present invention can provide other waveforms, such as triangle, square, sawtooth and pulse waveforms, and output frequencies can be provided well below audibility and well above audibility.
It is thus an object of the present invention to provide two well matched oscillators whose output signal frequencies can be varied simultaneously while a desired frequency difference is maintained between said output signal frequencies.
It is a further object of the present invention to provide such oscillators with a means for adjusting said frequency difference.
It is a further object of the present invention to provide such oscillators which provide signals whose frequency difference is stable over relatively long periods of time