GHz LC Voltage-controlled Oscillator Research Articles

Design of low power CMOS LC VCO for direct conversion transceiver

A low power 1.2 GHz LC differential voltage-controll ed oscillator (VCO) is designed for a direct conversion transceiver in 130 nm CMOS processes. It consists of a complementary current reuse structure and LC tank circuit. To produce a good tuning range and reduce losses in the tank circuit, modied inversion mode PMOS varactors and an on-chip inductor are designed with a better quality factor. The icker noise is reduced by the PMOS tail current source connected in parallel with the capacitance. The 1.2 GHz LC VCO achieves a phase noise value of {132 dBc/Hz at 1 MHz offset and the tuning range of the oscillator is from 1.128 to 1.27 GHz for the control voltage, tuning from 0 to 1.5 V. It dissipates 245 W power at 0.8 V supply voltage and thegure of merit is calculated as {199.7 dBc/Hz.

A 5-GHz LC VCO with digital AAC and AFBS for 2.4 GHz ZigBee transceiver applications

A 5GHz LC VCO (voltage-controlled oscillator) with automatic amplitude control (AAC) and automatic frequency-band selection (AFBS) for 2.4GHz ZigBee transceivers is presented. Instead of continuous feedback loop, an alternative amplitude calibration scheme is proposed in this paper to alleviate the deficiencies inherent in the conventional approach. It helps to keep the VCO at optimum amplitude to avoid saturation of the cross-coupled transistors and therefore stabilizes the phase noise performance over process, voltage and temperature variations. For the ZigBee application with 16 frequency channels, a coarse tuning loop is added in this work to implement the frequency-band selection using the AFBS mechanism. The VCO core and the digital AAC, AFBS modules have been fully integrated in a 2.4GHz ZigBee transceiver which was fabricated in a 0.18μm RF-CMOS technology. The current consumption is 4.7mA at 4.85GHz with 1.8V power supply and a chip area of about 0.285mm2 is occupied. The VCO is capable of operating from 4.67GHz to 5.18GHz and the measured phase-noise level is –120dBc/Hz at 1MHz offset from a 4.85GHz carrier. The tuning sensitivity KVCO of the VCO is about 78MHz/V with 0.9V control voltage.

Design of 4.48–5.89 GHz LC-VCO in 65 nm RF CMOS Technology

This paper describes a 4.48 GHz–5.89 GHz LC voltage-controlled oscillator (LC-VCO) as a key component in RF transceivers. The circuit is fully designed in TSMC’s 65 nm radio-frequency complimentary metal-oxide-semiconductor technology process. The LC-VCO uses the structure of only one couple of NMOS differential negative resistances, tank circuit which consists of an optimal on-chip spiral inductor with switched capacitor and varactor arrays. The proposed design accomplishes wide tuning range frequency by using 6-bit switch capacitor array in addition to linearly varying MOS varactors. A switched current source block is used to improve the performance of the LC-VCO. The oscillator has a wide tuning range, between 4.48 GHz and 5.89 GHz. The LC-VCO dissipates 15.96 mW from a voltage supply of 1.8 V, whereas its phase noise is -124.1 dBc/Hz at 1 MHz offset of a at 5.89 GHz carrier. DOI: http://dx.doi.org/10.5755/j01.eee.20.2.6383

Ultra-Low Power, Low Phase Noise 10 GHz LC VCO in the Subthreshold Regime

A new design for an ultra-low power, low phase noise differential 10 GHz LC voltage-controlled oscillator (VCO) which is biased in the subthreshold regime, is presented in the 0.18 μm CMOS process, for the first time. The designed circuit topology is an NMOS only cross-coupled LC-tank VCO which has an extra symmetric centre tapped inductor between the source ends of the cross-coupled transistors. Using this inductor leads to an improvement of the phase noise of VCO about 3.5 dB. At the supply voltage of 0.46 V, the output phase noise is －107.8 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 10.53 GHz, so that the dc power consumption is only 0.346 mW. Tuning range is between 10.53 GHz to 11.35 GHz which is 7.5% and the figure of merit is －193.8 dB, which this result shows that this is the first VCO design in the subthreshold regime at this frequency. This VCO can be used for multi-standard wireless LAN communication protocols 802.11a/b/g easily by a frequency division of 2 or 4 respectively.

An ultra-low power ISM-band integer-N frequency synthesizer dedicated to implantable medical microsystems

In this article, the architectural choices and design of a fully integrated integer-N frequency synthesizer operating in the 902---928 MHz Industrial, Scientific and Medical (ISM) band is presented. This frequency synthesizer, optimized for ultra-low power operation, is being integrated in the transceiver of an implantable wireless sensing microsystem (IWSM), which is dedicated to in vivo monitoring of biological parameters such as temperature, pressure, pH, oxygen, and nitric oxide concentrations. This phase-locked loop-based synthesizer includes a 1.830 GHz LC voltage-controlled oscillator (VCO) using a 10 nH on chip inductor. Varactors are implemented using P+ in N-well diodes for their linearity and high quality factor. The transistors of the VCO are operated in moderate inversion, and their bias point was chosen using the g m/I d design methodology. The output of the VCO, operating at twice the ISM frequency band, is divided by 2 to generate differential, quadrature versions of the carrier. Power minimization of the programmable divider was achieved by designing the latches and flip-flops using appropriate circuit techniques such as True Single Phase Clocking (TSPC) and first-type Dynamic Single Transistor Clocking (DSTC1) depending on their operating frequency. The power consumption of the proposed synthesizer is 580 μW under 1 V; almost an order of magnitude lower compared to that of recent synthesizer designs having a similar architecture.