An analog linearizer using second harmonic signal mixing operation

In this paper, a predistortion linearizing method using second harmonic signals down-conversion mixing operation is proposed. The harmonic generator, which used small signal transistor with abnormal bias condition, generates the second harmonic signals. To generate IMD3 signals, we used the extracted signal as mixing signal source. These signals are combined fundamental signals with out of phase. As a result, this predistorter suppressed the intermodulation distortion signals of power amplifier effectively. The suggested predistorter has been manufactured to operate in cellular base-station transmitting band (869-894MHz). The test results show that IMD3 has improved about 25dB for CW two-tone signals. For an IS-95 CDMA signal amplification, it has improved the adjacent channel power ratio(ACPR) more than 7.5dB and 6.4dB at ±750KHz and ±1.98MHz offset frequency.