MICROWAVE ACTIVE INDUCTOR ANALYSIS AND DESIGN

With the advancement in the microwave integrated circuit technology, the microwave active inductor is gradually being used as a substitute for spiral inductor in microwave integrated circuit design. The aim is to reduce the microwave integrated circuit size and to achieve a better quality factor, more broadband and higher value inductance. The conventional passive inductor has an intrinsic resistance and a stray capacitance, which will severely affect its quality factor and available frequency band in the circuit design. In this project, some novel microwave active inductors and the designed circuit configurations are presented. Their quality factors, frequency characteristics and equivalent impedances are analyzed. In addition, a novel loss compensation technique by an active RC feedback network is proposed to improve the quality factor. This loss compensation technique is really needed mainly because there exist some internal losses and other parasitic losses in the active devices. The total loss of an active inductor is equivalent to a frequency­ dependent resistance, which is in series with the active inductance. The amplification of the active devices can be equivalently represented by a frequency-dependent negative resistance. By adjusting the active RC network, the negative resistance will counteract with the loss so as to result in a broadband characteristic. As a result of this, it is possible to realize a high Q and broadband active inductor. In this project, a symmetrical microwave active inductor network is also designed, fabricated and tested. The applications of the network are verified by building a band pass filter and a low pass filter.

Author dc:creator

• LI WEI