Sinusoidal waveform generator

Claim 2

Apparatus for generating a sinusoidal wave form of a predetermined frequency which have a relatively low harmonic content, comprising a digital frequency synthesizer, said synthesizer having a multiplicity of output circuits where a square wave of a fundamental frequency related to said sinusoidal wave form and where additional square waves corresponding to odd harmonics of said fundamental appear with the amplitude of each square wave being inversely proportional to the frequency thereof; a multiplicity of driving circuits; means for coupling said square waves to the inputs of said driver circuits; a like multiplicity of transformers; means for coupling the primary of each transformer to the output of a different driving circuit; means for interconnecting all of the secondaries of said transformer in a series circuit; and an integrator connected across said series circuit thereby to develop said sinusoidal wave form.

Claim 3

Apparatus for generating a sinusoidal wave form of low harmonic content comprising, in combination, a source of clock pulses; a digital frequency synthesizer having a first plurality of output circuits at which square wave signals of fundamental frequencies f1, f2, . . . fn are produced, a second plurality of output circuits at which square wave signals of the third harmonics 3f1, 3f2, . . . 3fn are produced, and a third plurality of output circuits at which square wave signals of the fifth harmonics 5f1, 5f2, . . . 5fn are produced in response to clock pulses fed to the input of said frequency synthesizer with the amplitude of the third and fifth harmonic signals being one-third and one-fifth that of the fundamental, respectively; means for feeding said clock pulses to the input of said frequency synthesizer, thereby to produce said square waves of said fundamental, third and fifth harmonics; a pulse driver for each plurality of output circuits having an input and output circuit; means for coupling a square wave of a selected fundamental frequency and the square waves of the corresponding third and fifth harmonics to the input circuit of a different pulse driver; a transformer for each pulse driver; means for coupling the primary Of each transformer to the output circuit of a different pulse driver; means for interconnecting all of the secondaries of said transformers in an additive series circuit; and an integrator connected across said series circuit thereby to develop said sinusoidal wave form.

Claim 4

Apparatus for generating a sinusoidal wave form of low harmonic content comprising, in combination, a source of clock pulses; a digital frequency synthesizer having a first plurality of output circuits at which square wave signals of fundamental frequencies f1, f2, . . . fn are produced, a second plurality of output circuits at which square wave signals of the third harmonics 3f1, 3f2, . . . 3fn are produced, and a third plurality of output circuits at which square wave signals of the fifth harmonics 5f1, 5f2, . . . 5fn are produced in response to clock pulses fed to the input of said frequency synthesizer with the amplitude of the third and fifth harmonic signals being one-third and one-fifth that of the fundamental, respectively; means for feeding said clock pulses to the input of said frequency synthesizer, thereby to produce said square waves of said fundamental, third and fifth harmonics; a pulse driver for each plurality of output circuits having an input and output circuit; means for coupling a square wave of a selected fundamental frequency and the square waves of the corresponding third and fifth harmonics to the input circuit of a different pulse driver; a transformer for each pulse driver; means for coupling the primary Of each transformer to the output circuit of a different pulse driver; means for interconnecting all of the secondaries of said transformers in an additive series circuit; and an integrator connected across said series circuit thereby to develop said sinusoidal wave form.