High frequency digital synthesizer with aperiodic correction optimizing the spectral purity

A high frequency digital synthesizer with periodic corrections optimizing the spectral purity with high time precision, comprising:

• a generator of reference clock signals of frequency F.sub.C,
• a computing device which, from a frequency increment of the signal to be synthesized, delvers on the one hand uncorrected pulses of frequency F.sub.Sj shifted in time with respect to the signal to be synthesized of frequency F.sub.S by an amount .DELTA.t at most equal to 1/F.sub.C and, on the other hand, a time error signal corresponding to the shift .DELTA.t, and
• a correction circuit coupled to said computing device for delaying the signal F.sub.Sj by a maximum time when the timing error signal is zero and by an amount equal to the maximum time reduced by the shift .DELTA.t indicated by the timing error signal,
• said computing device comprising at least an accumulator register, incremented at a constant steps at the reference frequency F.sub.c of the clock signal generator having an overflow output for delivering uncorrected pulses of frequency F.sub.Sj whenever the maximum capacity of the accumulator register is reached and having an output D for delivering the contents of said accumulator register to said correction circuit and initializing said correction circuit, after each overflow of the maximum capacity of the accumulator register, by the content of said accumulator registor which represent at this time said time error signal.