I did it with a microcontroller PIC some time ago. I used the pwm at 50Khz and I load a vector with the value of sin of interest, the next step was to filter the PWM fundamental freq.
All of these IC's use an external input voltage to vary the frequency. I am not sure if you used these personally yourself, but how do they perform if you use a DAC as a digital control input voltage?
There's several technologies to generate sinewaves,
For low precision and low frequency, use op based oscillator circuit.
for high precision at low to medium frequency(below 100 MHz), DDS is cool.
for high precision and high frequency, DDS+PLL is a good option.
mike
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