A New Approach to the Design of High Dynamic Range Tunable Active Inductors

In this paper a new method for the design of tunable grounded active inductors with high dynamic range is described. The tuning technique is based on the use of a passive tunable compensating network in combination with a highly linear non-tunable capacitance gyrator. The circuit has high linearity with moderate noise figure, resulting in a high dynamic range. A prototype of an active inductor is presented, together with its application in a simple tunable bandpass filter, demonstrating the performances of the active inductor. The filter has a centre frequency tunable from 880MHz to 1100MHz, a bandpass of approximately 20 MHz, a 17dB noise figure and a 1dB gain compression point between 5dBm and 8dBm. The resulting dynamic range in the given bandpass is 90 dB, allowing its use for example as an IF filter for high dynamic range applications.