X-band and K-band low-phase-noise VCOs using SiGe BiCMOS technology

Abstract

From the past two decades, SiGe transistors have been identified as excellent candidates to match requirements both for high purity signal generation and high frequency applications. Moreover, SiGe BiCMOS technology takes benefit of CMOS devices that allow high integration levels for Monolithic Microwave Integrated Circuits (MMIC) Phase Locked Loop (PLL) systems. This work focuses on the only analog circuit of a PLL: the Voltage Controlled Oscillator (VCO) is one of the key stone of a transceiver, because its stability mainly influences the data rate of the channel. X-band and K-band VCOs are investigated. Design rules are thus compared for two different topologies in the X-band. K-band VCO is also designed to assess the technology behavior for higher frequencies. State of the art results are obtained and compared with the best published performances to date. New expressions of Figures Of Merit (FOM) are proposed to provide an accurate comparison between designs featuring scattered performances. IntroductionBiCMOS SiGe technologies offer great opportunities due to the high integration level with both analog and digital circuits operating at high frequencies, and also base-band modules matched to modern telecommunication systems' requirements. Moreover, the high performance (low noise, high operating frequency,…) associated with the relative low-cost gives advantage to such technologies in comparison with III-V foundries. The low frequency flicker noise (1/f) of SiGe Heteronjunction Bipolar Transistors (HBT) allows the design of MMIC voltage controlled oscillators (VCO) featuring excellent phase-noise: we present different VCO designs manufactured using the STMicroelectronics BiCMOS 0.35 µm and 0.25 µm processes for X-band and K-band applications.The paper is divided in three main sections. In the first part is presented a comparison between the reflection architecture (negative resistance) and the parallel feedback architecture operating in X-band. The second section presents the push-push differential oscillator in K-band. The last section proposes a comparison of this work with state of the art MMIC circuits: a new figure of merit (FOM) is introduced.

A K-band differential Colpitts cross-coupled VCO in 0.13μm CMOS

“…The second FOM of the proposed VCO is about À171.38 dBc/Hz, it is calculated using the figure of merit defined as [10][11][12] …”

“…It requires a low phase noise, low cost, and high output power. A lot of VCO circuit architectures such as cross-coupled oscillators [2], Colpitts oscillator [3,4] and Hartley oscillator [5] can be used to design a high performance K-band VCO. Despite so many options available, design and optimization of an integrated K-band LC VCO still pose many challenges to circuit designers as simultaneous optimization of multiple variables is required.…”

Evolution Trends and Paradigms of Low Noise Frequency Synthesis and Signal Conversion Using Silicon Technologies

“…Nevertheless, in Equation ( 2), the SSB rejected noise is already normalized by the output power in L ( f m ). These considerations have been used to augment Equation (2) into FoM P RF by formally considering such a signal swing (then dynamic power P out ) in Equation (3) [16], as it decides whether or not a buffer amplifier is needed when connecting the VCO to the mixer.…”

“…In addition, since this is evaluating tunable oscillators, Equation (4) adds the tuning range in the previous equations, expressed in percentage through TR% in FoM P RF &T , with a small adjustment from the expression first proposed in [16] and also used in other works, some of them being referenced in the dedicated figure later in this article.…”

Design, realization, and test of a 2.1‐GHz low‐phase‐noise oscillator based on BAW resonator

“…From previous work [10], it has been found that emitter‐base V be (which controls I c ) fluctuations mainly influence the phase noise for bipolar devices. Furthermore, according to the phase‐noise model of Hajimiri and Lee [11], the transistor should be operated in class C under oscillation conditions to reduce significantly the phase noise due to the cyclostationary noise.…”