Wideband BiCMOS VCO for GSM/UMTS direct conversion receivers

Abstract

With the increasing number of mobile communication standards, a large research effort is put into the task of complete integration of RF voltage-controlled oscillators (VCOs) for multi-band and multi-mode direct conversion transceivers. However, RF VCOs are, at present, not fully integrated in transceivers, since they suffer from poor phase noise and fabrication tolerances.

A 1.8-GHz LC VCO with 1.3-GHz tuning range and digital amplitude calibration

“…The equivalent parallel tank impedance at resonance is a strong function of the oscillation frequency and inductance , and is given by (1) where the overall tank quality factor is assumed to be dominated by inductor losses characterized here by the physical series resistance of the coil, which eventually becomes a function of frequency due to skin/proximity effects and substrate eddy current induced losses. The above equation is valid as long as the capacitive elements of the tank have a significantly higher than the inductor, which may not hold true at very high frequencies.…”

“…The VCO performance in terms of phase noise and tuning range determines basic performance characteristics of a transceiver. The current trend toward multiband multistandard transceivers and broadband systems has generated interest in VCOs that simultaneously achieve very wide tuning range and low phase noise performance [1]- [9]. Whereas relaxation oscillators easily achieve very wide tuning range (i.e., 100% or more), their poor phase noise performance disqualifies them in many of today's wireless and wireline applications.…”

“…Because LC VCOs have been successfully used in narrowband wireless transceivers, there is a growing interest in extending their tuning range. Recently, several wideband CMOS LC VCOs have been demonstrated using a variety of techniques [1]- [4]. The high intrinsic of inversion-or accumulation-type MOS varactors supports a very wide tuning range and their is sufficiently high that good phase noise performance can be maintained [3].…”

A wideband low-phase-noise CMOS VCO

“…Table 2 shows how this number compares to some other notable published VCOs implemented in bulk CMOS. With the exception of [3], the FOM for our VCO compares favorably to the others listed in Table 2. The design presented in [3] …”

“…Because LC VCOs have been successful in narrowband wireless transceivers, there is a growing interest to extend their tuning range. Recently, several wideband CMOS LC VCOs have been demonstrated using a variety of techniques [1][2][3][4]. The high intrinsic C max /C min of inversion-or accumulation-type MOS varactors supports a very wide tuning range and their Q is sufficiently high that good phase noise performance can be maintained.…”