About the SineCore Modulator
The SineCore Modulator is based on a design by Barrie Gilbert from 1977. It uses a series of cascaded differential amplifiers to smoothly change the polarity of the output signal as the input voltage is increased. This became the basis for the AD639 "Universal Trigonemtric Function Converter" IC from Analog Devices, Inc. The SineCore Modulator can produce +/-720 degrees of a relatively low distortion sinewave. Over the first +/-90 degrees, the THD is around -80dB, making it very useful for triangle or sawtooth to sinewave conversion. If the amplitude of the input signal is modulated, the number of reversals increases, essentially acting as a quadruple wavefolder. When a sawtooth wave is applied, it can be summed with a DC offset to produce sinewave Phase Modulation (PM) with through-zero capability.
How to Use the SineCore Modulator