Voltage-Controlled Oscillators and Process Variation Monitors
Date Issued
2010
Date
2010
Author(s)
Hsieh, Yi-Ying
Abstract
In this thesis, three voltage-control-oscillators (VCOs) are designed. The first two VCOs equip process variation monitors to improve circuit performance. The other one is a push-push VCO that can operate faster than transistor unit current-gain frequency (ft).
The first work uses 0.18μm CMOS process. Since bond wire inductors have high quality factors without occupying much chip area, we use them to implement the VCO. A triode biased tail current transistor is used in this VCO. Since the triode biased transistor suffers from large process variations, a process variation monitor circuit is designed and implemented to solve the issue. This VCO has the tuning range of 600MHz. Without any calibration, VCO core power consumption is 4.2mW, and it has phase noise -108.56(dBc/Hz) at 1MHz offset. After calibrated by the process variation monitor, VCO core power consumption is 2.64mW and measured phase noise -106.31 dBc/Hz at 1MHz offset. Power consumption after calibration is reduced to 63% only, and this design has the highest output frequency among recently reported bond wire VCOs.
Then a new process variation monitor is designed using 90nm CMOS process. Since using triode biasing scheme usually needs more power, this 90nm CMOS VCO is biased in the saturation region instead. The gate bias of the tail current transistor is tuned by the process variation monitor. This design uses inner inductors and oscillates at 11GHz. From the simulation results, the tuning range of the oscillator is 720MHz, phase noise is -104.5 dBc/Hz at 1MHz offset, and the power consumption is 1mW.
Finally, the design of a cross-coupled push-push VCO in 90nm CMOS is presented. The supply voltage is 0.9V. The measurement result of the push-push port is 111GHz. Output power is -23.1dBm, and phase noise is -95.8(dBc/Hz) at 1MHz offset.
Subjects
Bondwire
voltage-controlled oscillator
phase noise
process variation monitor
Type
thesis
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