Oversampling architecture for analog harmonic modulation

We propose a technique for sinusoidal modulation of analog signals, which requires neither multiplication nor analog sine wave generation. The modulating signal is an oversampled representation of a sine in the form of a periodic binary sequence, optimized to minimize intermodulation distortion. A 2-to-1 multiplexer performs the modulation multiplication. With third-order low-pass filtering of the input signal, the technique achieves 60 dB of linear dynamic range for a sequence of length 256, conveniently generated with an 11-address decoder and an 8-b counter.