MOSFET Based Absorber for Reflected Signal in 5G Massive MIMO Base Station - A Circuit Perspective

A lossy transmission has negative effect on the overall performance and efficiency of base station subsystems. One key feature of 5G technologies is improved efficiency compared to 4G technology. The 5G massive-MIMO base station structure may suffer from these losses, which affect the inclusive performance and efficiency of the base substation. Furthermore, in the 5G technology, loss is anticipated due to the reflection of signals from the receiver (Rx) branch connected to the circulators in the 5G MIMO base station. This reflection loss is due to the mismatched load impedance of the Rx branch with the source impedance of transmitter (Tx) branch. The main objective of this research is to use MOSFET to absorb the reflected signal resulting from impedance mismatching between the Tx and Rx. After that, two comparisons have been made between source current and drain current of the MOSFET mathematically, whenever there is a reflection from the Rx branch of the base station. In addition, the proposed circuit model has been presented by connecting the Tx branch, antenna, Rx branch, and the MOSFET to each of the ports of a four-port circulator. A reflected RF power of 13 dBm at 1.4 V peak is rectified to its equivalent DC value 1.004 V. However, these values of current and voltage are pulsating and filtered at the output end of the rectifier with the use of an LC Filter.

Nonlinear Membrane Circuit Loaded on a Lossy Transmission Line without the Heaviside’s Condition

The paper deals with transmission lines terminated by a nonlinear circuit describing a simplified model of membrane. This means that all elements of the membrane circuit are nonlinear ones as follows: in series connected LR-loads parallel to C-load. Using the Kirchhoff’s laws we formulate boundary conditions. For lossy transmission lines systems with the Heaviside’s condition, the mixed problem is considered in previous papers. The main goal of the present paper is to investigate the same problem for lossy transmission lines without the Heaviside’s condition. We reduce the existence of solution of the more complicated mixed problem for such a system to the existence of fixed point of an operator acting on a suitable function space. Then by ensuring the existence of this fixed point we obtain conditions for existence of a generalized solution of the mixed problem. The obtained conditions are easily verifiable. We demonstrate the advantages of our method by a numerical example.