A new broadband bipolar electrical controlled attenuator

Adaptive interference cancellation technology is widely used in kinds of noise rejection systems to resolve EMI problems, while a broadband bipolar electrical controlled attenuator is as one of the most important components in these systems. In this paper, we devise a new bipolar electrical controlled attenuator design scheme that bases on π type PIN diode variable attenuator. The attenuator is achieved by using π type PIN diode attenuation circuit as the variable part and PIN diode switch to select the output polarity of the transmission line transformer. The results of experiment show that within the operation frequency 2MHz-30MHz, the attenuator has a Standard Voltage Wave Ratio (SWR) less than 1.6, the dynamic range up to 60dB, the Insertion Loss(IL) less than 5dB and the anti-phase error less than 5 degree.