چكيده به لاتين
In this thesis, a new RF-input LMBA structure is proposed for linear operation at 800MHz frequency. typical telecommunication signals require linearity below -40dBc, and the goal is to achieve this level of linearity in a dynamic range of 10dB, because these signals often have a PAPR of about 10dB to 12dB. For this purpose, in the former RF-input LMBA structure, an attenuator block is also used in the control branch in addition to the phase shifter block. The goal is to generate a load trajectory by properly setting this phase shifter and this attenuator block. For 7.65dB attenuation and 85° phase shift, the desired linearity characteristic is obtained. Considering that second harmonic injection has a good effect on improving the linearity, in this thesis, this method is also used to improve the linearity of the desired structure. For this purpose, considering that the control amplifier of RF-input LMBA structure is used in saturation mode, and this leads to the presence of the second and third harmonics in the output of the control amplifier in addition to the first harmonic, the second harmonic generated by the control amplifier is used to improve the linearity of the structure. The generated second harmonic is separated by the filter and sufficiently amplified and then applied to the input of each of the main amplifiers of the RF-input LMBA structure with different attenuation and phase shift. In this thesis, two plans are proposed for this purpose. In the first scheme, for linearization, there is only the second harmonic injection, without the control signal injection, but in the second scheme, the simultaneous injection of the second harmonic along with the control signal injection is used for linearization. In the first plan, for the value of 9.76dB gain and the values of 0dB and 9.5dB attenuation and the values of 58° and 178° phase shift, the best linearity mode is obtained, and the linearity in this mode approaches the desired linearity characteristic but does not reach it. In the second design, for the value of 5dB attenuation and the value of 73° phase shift for the control branch and the value of 25dB gain and the values of 15dB and 16dB attenuation and the values of 254° and 237° phase shift for the second harmonic signal branches, the best linearity is obtained. In this case, in the dynamic range of 12.5dB of output power, IMD3 is below -40dBc, i.e., 2.5dB improvement in the dynamic range compared to the case where only control signal injection is used for linearization.
