DRIVING A MIXER WITH A DIFFERENTIAL LO SIGNAL HAVING AT LEAST THREE SIGNAL LEVELS

摘要

The mixer of a transmit chain of a wireless transmitter (such as the transmitter of a cellular telephone handset) is driven with low third harmonic in-phase (I) and quadrature (Q) signals. The low third harmonic I and Q signals have three or more signal levels, and transition between the these three or more signal levels at times such that each of the I and Q signals approximates a sine wave and has minimal third harmonic spectral components. In one example, reducing the third harmonic components of the I and Q signals simplifies design of amplifier stages of the transmitter and helps reduce receive band noise.