In this paper, an active inductor (AI) with high linearity and high dynamic range, including a minimum number of components, is presented. The AI is composed by a single transistor, and by a passive compensation network; the latter allows the control of the values of both the inductance and the series resistance.In order to show the feasibility of the proposed AI for filter applications, a prototype board on a TLX8 substrate with a first-order active band-pass filter has been fabricated and tested. The filter has a center frequency of 2470 MHz (useful for Bluetooth applications) and a measured noise figure (NF) of 9 dB with a À5 dBm P 1 dB compression point, and a 75 dB dynamic range.By considering the filter NF, bandwidth and the P 1 dB, compression point, the dynamic range of the filter from noise floor (À174 dBm/Hz) to P 1 dB compression point is approx. 75 dB. The power consumption is approx. 5 mW. Linear and nonlinear analysis and measurements have shown an unconditionally stable filter response. A table resuming the aforementioned performance is given (see Table I) showing also comparisons with the state of the art. For all these reasons, the natural application of the proposed filter is as a post-selector in radio communications systems, after the low noise amplifier, or as a channel selector in the receiver IF chain. Moreover, it can be used for RF or microwave band selection application, as wakeup radio systems [29], where high dynamic range and selectivity are required without stringent noise performance.
CONCLUSIONSWe have proposed a high-Q, high-linearity, and high dynamic range AI, requiring a minimum number of components. A high quality factor band-pass filter including the AI has been designed as a demonstrator. A prototype board on a TLX8 substrate has been fabricated and tested in order to show the AI feasibility for RF and microwave applications. The filter has a center frequency of 2470 MHz, in the Bluetooth frequency range, a measured NF of 9 dB, and a À5 dBm P 1 dB compression point. The resulting 75 dB dynamic range confirms the theoretical predictions and simulation results. The proposed AI, if properly designed, is unconditionally stable in the whole frequency range and can be used in practical applications. We remark that this aspect is usually underestimated in the literature, and, to our best knowledge, only few works give information about AI stability, power handling, and noise. SINGLE TRANSISTOR ACTIVE INDUCTOR 285