Booske, "Third-order intermodulation
reduction by harmonic injection in a TWT amplifier," IEEE Transactions on Electron Devices, vol.
The main PA amplifies the original input signal and the predistortion signal; the output signals include the amplified original signal, its third-order intermodulation
signal and the amplified predistortion signal, which is opposite in phase to the intermodulation signal.
The generation of a third-order intermodulation
component (IM3) when two sinusoidal signals (Acos[[omega].sub.1]t, Acos[[omega].sub.2]t) are applied at the input of the functional block f(x) yields
From the values of the capacitances and conductances, the Volterra series was then used to predict the level of the third-order intermodulation
and its variation with input power level and operating frequencies.
The measured third-order intermodulation
distortion (IMD3) is -43.67 dBc.
However, the [C.sub.gs] dependency on [V.sub.gs] was found to significantly affect power saturation and the third-order intermodulation
For example, Figure 4 shows measured and simulated third-order intermodulation
(IM3) products versus current at various values of collector voltages.
In particular, lower third-order intermodulation
products and higher RF power handling capabilities, together with a low insertion loss, are required for all components of the base station transmit chain and specifically for isolators and circulators.
Since the four diodes can operate at different operating points, the harmonic generator easily generates the third-order intermodulation
(IM3) or the fifth-order intermodulation (IM5) components individually.
Usually this method is applied to the third-order intermodulation
(IM3) components of the signals.
The WCDMA standard sets a two-tone test for third-order intermodulation
at 10 and 20 MHz offsets from the carrier.
The effect of the intermodulation product may appear in a few different forms such as third-order intermodulation
, adjacent channel power (ACP) of an adjacent channel modulated interferer and second-order intermodulation.