The Output Compare Modulator (OCM) allows generation of waveforms modulated with a carrier frequency. The modulator uses the outputs from the Output Compare Unit B of the 16-bit Timer/Counter3 and the Output Compare Unit of the 16-bit Timer/Counter4. For more details about these Timer/Counters see 16-bit Timer/Counter. When the modulator is enabled, the two output compare channels are modulated together as shown in the block diagram (as the following figure).

Figure 1. Output Compare Modulator, Block Diagram