Seok-Ju Yun

A 1mW current-reuse CMOS differential LC-VCO with low phase noise

An LC-VCO with halt of the power dissipation of a that of the conventional topology is presented. The LC-VCO replaces one of the NMOSFET of the conventional differential LC-VCO with a PMOSFET. The operational principles and design guidelines of the proposed topology are reported. The proposed LC-VCO is implemented in a 0.18 /spl mu/m CMOS technology for 2GHz applications and measurements show phase noise is -103dBc/Hz at 100kHz offset while dissipating 1mW from a 1.25V supply.

A 2.2-mW Backgate Coupled

This letter presents a backgate coupled quadrature voltage-controlled oscillator (QVCO) which consists of a pair of current reused LC-VCOs. The proposed QVCO is designed for 2-GHz operation based on a 0.18-mum triple-well CMOS technology. Measurements show -102 and -124dBc/Hz at 100-kHz and 1-MHz offset, respectively. Compared to the conventional QVCO, the proposed QVCO dissipates significantly lower power (1.74mA from a 1.25-V supply) while showing good 1/f3 close-in phase noise

LC

This letter proposes a new method to suppress the 1/f noise contribution of active devices in an oscillator using source damping resistors. The operational mechanism of the proposed source damping resistor method is analyzed through circuit simulation with a complementary LC-oscillator. The reduced 1/f noise leads to the phase noise improvement by suppressing 1/f noise up-conversion to phase noise. The measurement result shows that there is about 6.0dBc and 4.0dBc of phase noise improvement at 10kHz and 100kHz offset frequency with differential complementary LC-oscillator topology, respectively

Quadrature VCO With Current Reused Structure

A dual-band wide-tuning range complementary LC-VCO is reported that utilizes additive and subtractive coupling of transformer inductances. Complementary circuitry in the VCO enables the frequency tuning range to be extended with boosted positive loop gains. Implemented in 65 nm CMOS, the measured results show frequency tuning range of 56% and 33% at 7.5 and 18.25 GHz center frequency, respectively, and phase noise of -98 ~ -112 dBc/Hz (FoMT of 187 ~ 202) at 1 MHz offset while dissipating 1.7 ~ 9.9 mW.

RF CMOS

This letter reports a cross-coupled transistor structure that allows simple routing, induces no gate-drain overlap interconnect capacitances, minimizes the parasitic resistances of interconnects, allows smaller drain-junction parasitic capacitances, and provides inherent common-centroid characteristic, all of which help to improve the high-frequency and wideband performances of CMOS voltage-controlled oscillators (VCOs). The proposed cross-coupled transistor structure is applied for a 26.2-GHz differential VCO design which dissipates 7.3 mA from 1.8-V supply using 0.18-mum CMOS. Measurements show 2.1-GHz, 29%, and 4-dB improvements in operating frequency, tuning range, and phase noise compared to those of the VCO using a conventional cross-coupled transistor layout, respectively. The VCO with the proposed transistor structure shows the phase noise of -113.7 dBc/Hz at 1 MHz, which corresponds to FOM and FOMT of -190.4 and -194 dBc/Hz, respectively.

LC

This letter proposes a new voltage controlled oscillator (VCO) topology that cancels common-mode noise by adoption of differential tuning varactor. To suppress common mode noise effectively, a symmetric three-coil transformer is proposed as a differential tuning resonator. The measured phase noise shows -128.7 dBc/Hz at 1 MHz offset frequency from the 1.2 GHz oscillation frequency. Over the whole frequency range, common-mode noise rejection is larger than 36 dB. Measured tuning range of the proposed VCO is about 204 MHz from the 1.18 GHz to 1.38 GHz while dissipating 1.2 mA at 1.8 V power supply.

-Oscillator With Source Damping Resistors

A mixer implementing a cross-coupled bleeding circuit for improved conversion gain and noise performance is reported. The proposed mixer is implemented in 0.18 μm CMOS technology. The measured results show a 17 dB conversion gain, - 4.7 dBm IIP3 for an RF signal frequency of 765 MHz, 7.9 dB noise figure, and 125 kHz flicker noise corner while consuming 3.12 mA from a 1.8 V supply.

A Wide-Tuning Dual-Band Transformer-Based Complementary VCO

A complementary cross-coupled differential Colpitts voltage controlled oscillator (VCO) is reported. The combination of gm-boosting and the complementary transistors allows record low power integrated VCO implementation. The proposed VCO and the corresponding parallel quadrature VCO (P-QVCO) are implemented using 0.25-μm CMOS technology for 1.8 GHz operation. Measurements for the VCO and P-QVCO show phase noise of -116.8 and -117.7 dBc/Hz at 1 MHz offset, while dissipating only 0.4 and 1.1 mA from a 0.9-V supply, respectively.

A Low-Parasitic and Common-Centroid Cross-Coupled CMOS Transistor Structure for High-Frequency VCO Design

A new CMOS voltage-bias differential LC voltage-controlled oscillator (LC-VCO) with active source degeneration is proposed. The proposed degeneration technique preserves the quality factor of the LC-tank which leads to improvement in phase noise of VCO oscillators. The proposed VCO shows the high figure of merit (FOM) with large tuning range, low power, and small chip size compared to those of conventional voltage-bias differential LCVCO. The proposed VCO implemented in 0.18-㎛ CMOS shows the phase noise of -118 ㏈c/㎐ at 1 ㎒ offset oscillating at 5.03 ㎓, tuning range of 12%, occupies 0.15 ㎟ of chip area while dissipating 1.44 ㎽ from 0.8 V supply.

A Differentially-Tuned Voltage ControlledOscillator Using Symmetric Transformer

This paper presents transformer-coupled VCO using symmetric transformer. By adopting cross-coupled transistors at both side of transformer, phase noise performance is improved by 6 dB compared with conventional VCO. The proposed VCO has been fabricated in CMOS 0.13..m technology. Measured results show -108 dBc/Hz phase noise at 1 MHz offset and frequency range 6.54~6.86 GHz while dissipating 2.1 mA from a 0.6 V supply.