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 880 MHz to 1100 MHz, a bandpass of approximately 20 MHz, a 17 dB noise figure and a 1 dB gain compression point between 5 dBm and 8 dBm. 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.