An approach for the design of high-Q active inductor (AI) with high dynamic range is presented. The proposed AI includes a passive variable phase- and amplitude-compensating network and a highly linear inverting amplifier, forming a gyrator-C architecture. The equivalent inductance and resistance values are tunable in a wide frequency range; outside the operating frequency band, the inductor equivalent resistance increases, improving signal rejection for band-pass filter applications. As a feasibility demonstration, a first-order active band-pass filter using the high-Q active inductance has been fabricated and tested. The filter has a center frequency of 600 MHz and a measured noise figure of 11 dB with a 5-dBm 1-dB compression point and an 82-dB dynamic range.

A Tuneable Active Inductor With High Dynamic Range for Band-Pass Filter Applications

A tunable CMOS active inductor is presented. The circuit uses a cross-coupled pair of transistors providing positive feedback for enhanced quality factor. The circuit is biased with a controllable current source varying the feedback and tuning the inductor. The proposed inductor is designed and simulated in a 90 nm digital CMOS process. It shows a wide-frequency range inductive impedance and a very high resonance frequency. By cascading two inductors, a wideband filter/amplifier is designed to characterise the inductor performance.

Wide tunable CMOS active inductor

In this paper, a 2nd order tunable RF CMOS LC bandpass filter with the on-chip inductor is presented. Q-enhancement and tuning are also considered. The Q-tuning is implemented through an adjustable negative conductance generator circuit. The simulated results show that the center frequency of the filter using a 0.18µm CMOS process can be operated from 1.90GHz to 2.42GHz frequency band under 3.3V supply by a set of capacitor array and the varactors that achieve the coarse and exact tuning respectively

A multi-band RF CMOS LC bandpass filter with continuous frequency tuning design

In one implementation, an amplifier (305) comprises a load circuit (310) comprising a plurality of inductor cells, and a drive circuit (314) configured to receive an input signal, and to drive the load circuit (310) based on the input signal to generate an amplified signal. The amplifier (305) also comprises a controller (350) configured to tune a peaking gain of the amplifier (305) by adjusting a number of the inductor cells that are enabled.

Amplifier with boosted peaking

A CMOS active inductor that exhibits wide-frequency range inductive impedance with a high quality factor (Q) is presented. The inductor is designed using negative impedance obtained in a cross-coupled transistor pair that is a part of the feedback loop consisting of common gate and common drain stages. Then, a tunable ultra-wideband (UWB) bandpass filter (BPF) is designed by cascading two such inductors back-to-back through a varactor. The proposed active inductor and the BPF are designed and simulated in 90nm CMOS digital process. The inductor exhibits inductive impedance in the range from few MHz to over than 20GHz and achieves Q-factor of 600. The designed BPF shows a −3dB bandwidth of 2.25GHz with a tuning range of 5GHz.

A wide frequency range CMOS active inductor for UWB bandpass filters

An active inductor based bandpass radio-frequency (RF) filter circuit topology is presented that achieves a wide tuning range. Based on the proposed structure, a prototype 2/sup th/-order filter is designed, simulated, and laid out in a 0.18/spl mu/m CMOS process. The center frequency of the filter can be tuned from 880MHz to 3.72GHz. The quality factor of the filter can also be tuned. The filter, including the input and output buffers, consumes between 12 to 26mW from a 1.8V supply and occupies a chip area of 115/spl mu/m /spl times/ 70/spl mu/m.

K. Allidina

Papers

A widely tunable active RF filter topology