Novel Active Inductor Synthesis Method And Its Application In RF Circuits

Advanced deep sub-micron CMOS technology can provide better frequency characteristics and smaller chip area for radio frequency(RF)integrated circuits,and the trend of integrated circuits to system-on-chip(SOC)is becoming more and more obvious.At present,since the passive spiral inductor cannot be synchronously reduced with the advancement of deep submicron technology,it still has the disadvantages of occupying a large chip area,low quality factor,and non-tunable inductance,which limit its application in miniaturization and high-level integrated circuits.Compared with the passive planar spiral inductor,the active inductor synthesized by the MOS transistor not only has a small area,but also easier to adjust the inductance and Q value,which is beneficial to the full integration of the CMOS RF circuit.In this paper,through the research on the basic knowledge of active inductors and related RF circuits,two new types of active inductors are proposed,and two new active inductances are applied in voltage-controlled oscillator(VCO)and power divider respectively.The main work of this paper can be summarized as follows:(1)A miniature voltage-controlled oscillator based on a tunable active inductor is proposed,which is designed by a standard 0.18?m CMOS process with a total layout of only 0.47mm?0.35 mm.The VCO has been implemented by using tunable active inductors,injection current sources and a self-cascode negative resistor.Among them,the novel active inductor uses active feedback resistance and auxiliary capacitance to improve the inductance,and uses control voltage to change the active feedback resistance to achieve the tunability of the active inductor.The injection current source is used to open up a new DC path,which affects the DC bias current flowing through the active inductor negative transconductance amplifier.And the equivalent inductance and frequency range are adjusted,so that VCO has better frequency adjustment ability in order to obtain a larger frequency rang.Large negative resistance and high output impedance can be achieved with a self-cascode structure.The simulation results show that the oscillation frequency tuning range is from 0.50 to 2.34 GHz as the tuning voltage is varied from 0.6 to 1.6V,with a tuning range of 129%.A phase noise of-101.2dBc/Hz at 1MHz offset frequency is obtained for an oscillation frequency of 0.50 GHz and the total power consumption of the entire circuit is 19.6mW under a 1.8V supply voltage.(2)A miniature Wilkinson power divider based on high Q active inductor is proposed,which is designed by a standard 0.18?m CMOS process with a total layout of only 0.3mm? 0.4mm.Compared with the traditional Wilkinson power divider,the lumped parameter power divider based on active inductor can realize the miniaturization of the circuit and improve the circuit integration.The novel active inductor can achieve a high quality factor Q and a wide tuning range through the feedback loop.The simulation results of the power divider show that the insertion loss is 0.14 dB,the return loss of the input port is 36 dB and the output port is 41.6dB while the isolation between the two output ports is 39.2dB at 2GHz center frequency.At 1.8V supply voltage,the power consumption of the power divider is only 4.8mW.Moreover,by adjusting the external bias voltage of the active inductor,the center frequency of the power divider can be tuned in the frequency range of 1.5 GHz to 2.5 GHz.