A major drawback of orthogonal frequency-division multiplexing (OFDM) signals is their high peak-to-average power ratio (PAPR), which causes serious degradation in performance when a nonlinear power amplifier (PA) is used. Companding transform is a well-known method to reduce PAPR without restrictions on system parameters such as number of subcarriers, frame format and constellation type. Recen...

This work discusses an Evolvable Hardware (EHW) platform for the synthesis of analog electronic circuits. The EHW analog platform, named PAMA (Programmable Analog Multiplexer Array), is a reconfigurable platform that consists of integrated circuits whose internal connections can be programmed by Evolutionary Computation techniques, such as Genetic Algorithms, to synthesize circuits. The PAMA is...

The operational amplifier concept emerged from extensive development of electronic analog computers in the 1940s. Operational amplifiers get their name from their ability to perform mathematical operations such as summation, integration and differentiation. With the addition of logarithmic amplifiers and feedback, one may perform multiplication and division as well. These abilities allow op-amp...

Measurements of atmospheric corona currents have been made for over 100 years to indicate the atmospheric electric field. Corona currents vary substantially, in polarity and in magnitude. The instrument described here uses a sharp point sensor connected to a temperature compensated bi-polar logarithmic current amplifier. Calibrations over a range of currents from ±10 fA to ±3 μA and across ±20 ...

ABSTRACT In this paper, we present a temperature compensation method for logarithmic CMOS image sensors. As Bandgap technique, the compensation circuit generates VPTAT1 and VPTAT2 voltages to compensate temperature variation of the sensor output signal voltage (Out-AC-Signal) which we call VCTAT1 and output reference voltage (VRef−ph) which we call VCTAT2. The proposed method is divided into th...

This paper presents a fast received signal strength indicator (RSSI) circuit for wireless communication application. The proposed circuit is developed using power detectors and an analog-to-digital converter to achieve a fast settling time. The power detector is consisted of a novel logarithmic variable gain amplifier (VGA), a peak detector, and a comparator in a closed loop. The VGA achieved a...

a novel low noise trans-impedance amplifier is proposed using low cost 0.18 µm cmos technology. a resistive-capacitive feedback is used to extend the bandwidth of the amplifier. as the structure is inductor less, it is suitable for low cost integrated optical interconnects. in this paper improved particle swarm optimization have applied to determine optimal trans-resistance and noise of propose...

a digital look-up table adaptive predistortion technique using a six-port receiver for power amplifier linearization is presented. the system is designed in ka-band for a dvb-s2 satellite link. we use a six-port receiver at the linearizationloop in place of classic heterodyne receivers. the six-port receiver is implemented by the use of passive microwavecircuits and detector diodes. this approa...