Generalized Single Stage Class C Amplifier: Analysis from the Viewpoint of Chaotic Behavior

This paper briefly describes a recent discovery that occurred during the study of the simplest mathematical model of a class C amplifier with a bipolar transistor. It is proved both numerically and experimentally that chaos can be observed in this simple network structure under three conditions: (1) the transistor is considered non-unilateral, (2) bias point provides cubic polynomial feedforward and feedback transconductance, and (3) the LC tank has very high resonant frequency. Moreover, chaos is generated by an autonomous class C amplifier; i.e., an isolated system without a driving force is analyzed. By the connection of a harmonic input signal, much more complex behavior can be observed. Additionally, due to the high degree of generalization of the amplifier cell, similar fundamental circuits can be ordinarily found as subparts of typical building blocks of a radio frequency signal path.

Design of Broadband 1.9 GHz Ga as MMIC Switching Power Amplifier for PCS Communication Services

The paper presents a broadband Monolithic microwave Switching Class–E Power amplifier using 0.5μm GaAs E-pHEMT technology for PCS communications systems operating at 1900MHz.Wider bandwidth is achieved by employing reactance compensation technique in load network of the switching power amplifier. The main Power amplifier is a single stage Class-E circuit with a driver stage driving it to achieve high gain and efficiency. The modified load network using reactance compensation network results in higher power added efficiency. The paper provides simulation results of designed two-stage Class-E Power amplifier circuit results with an power output of 20dBm, power added efficiency of 80% and gain of 26dB at the centre frequency of 1.9GHz compared with various Class-E designs of 1.9 GHz using different technologies. A high linear gain is reported in the design at the frequency range of 0.8GHz to 2.2GHz.The designed circuit achieves a wider bandwidth of 1.35GHz over a frequency range of 0.8-2.2GHz.The physical layout is drawn using GaAs foundry components and EM simulation is performed

Design of a low-power compact CMOS variable gain amplifier for modern RF receivers

The demand for portability has speeded up the design of low-power electronic communication devices. Variable gain amplifier (VGA) is one of the most vulnerable elements of every modern receiver for the proper baseband processing of the signal. CMOS VGAs are generally suffered from low bandwidth and small gain range. In this research, a two-stage class AB VGA, each stage comprising of a direct transconductance amplifier and a linear transimpedance amplifier, is designed in Silterra 0.13-μm CMOS utilizing Mentor Graphics environment. The post-layout simulation results reveal that the VGA design achieves the widest bandwidth of 200 MHz and high gain range from -33 to 32 dB. The VGA dissipates only 2mW from a single 1.2 V DC supply. The core chip area of the VGA is also only 0.026 mm2 which is also the lowest compared to recent researches. Such a VGA will be a very useful module for all modern communication devices.