Numerically controlled oscillator

A numerically controlled oscillator (NCO) is a digital signal generator which creates a synchronous (i.e., clocked), discrete-time, discrete-valued representation of a waveform, usually sinusoidal.^[1] NCOs are often used in conjunction with a digital-to-analog converter (DAC) at the output to create a direct digital synthesizer (DDS).^[3]

Numerically controlled oscillators offer several advantages over other types of oscillators in terms of agility, accuracy, stability and reliability.^[2] NCOs are used in many communications systems including digital up/down converters used in 3G wireless and software radio systems, digital phase-locked loops, radar systems, drivers for optical or acoustic transmissions, and multilevel FSK/PSK modulators/demodulators.^[2]

^ ^a ^b Radatz, J. (1997). The IEEE Standard Dictionary of Electrical and Electronics Terms. New York, NY: IEEE Standards Office.
^ ^a ^b ^c "Numerically Controlled Oscillator". Lattice Semiconductor Corporation. 2009.
^ While some authors use the terms DDS and NCO interchangeably,^[2] by convention an NCO refers to the digital (i.e. the discrete-time, discrete amplitude) portion of a DDS^[1]

[IEEE-1] Radatz, J. (1997). The IEEE Standard Dictionary of Electrical and Electronics Terms. New York, NY: IEEE Standards Office.

[latticeSC-2] "Numerically Controlled Oscillator". Lattice Semiconductor Corporation. 2009.

[3] While some authors use the terms DDS and NCO interchangeably,^[2] by convention an NCO refers to the digital (i.e. the discrete-time, discrete amplitude) portion of a DDS^[1]

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