Phase noise and additive noise estimation in a QAM demodulator

A quadrature amplitude modulation (QAM) type demodulator comprising:

• an analog-to-digital converter receiving an input signal and producing a first signal,
• a baseband conversion circuit being electrically coupled to the analog-to-digital converter and receiving the first signal and producing a baseband signal,
• a carrier recovery circuit being electrically coupled to the baseband conversion circuit and receiving the baseband signal and producing a QAM signal, the carrier recovery circuit including a phase noise estimation circuit and an additive noise estimation circuit, the phase noise estimation circuit producing a phase noise estimated signal based on a first least mean square error, the additive noise estimation circuit producing an additive noise estimated signal based on a second least mean square error, wherein the phase noise estimated signal is independent of the additive noise estimated signal, and
• a symbol decision circuit being electrically coupled to the carrier recovery circuit and receiving the QAM signal,
• whereby an output signal of the symbol detection circuit is a demodulated data output signal.

A quadrature amplitude modulation (QAM) type demodulator comprising:

• an analog-to-digital converter receiving an input signal and producing a first signal,
• a baseband conversion circuit being electrically coupled to the analog-to-digital converter and receiving the first signal and producing a baseband signal,
• a carrier recovery circuit being electrically coupled to the baseband conversion circuit and receiving the baseband signal and producing a QAM signal, the carrier recovery circuit including a phase noise estimation circuit and an additive noise estimation circuit, the phase noise estimation circuit producing a phase noise estimated signal based on a first least mean square error, the additive noise estimation circuit producing an additive noise estimated signal based on a second least mean square error, wherein the phase noise estimated signal is independent of the additive noise estimated signal, and wherein the first and second least mean square error signals are defined as a difference between a point in I/Q coordinates of the received QAM signal and a point in I/Q coordinates of a decided QAM signal, the decided QAM signal being determined by the symbol decision circuit, and
• a symbol decision circuit being electrically coupled to the carrier recovery circuit and receiving the QAM signal after filtering,
• whereby an output signal of the symbol detection circuit is a demodulated data output signal.