Design of a 2.5‐GHZ QVCO robust against high frequency substrate noise

Abstract

This work presents the design procedure followed to obtain a low-power voltage-controlled oscillator (VCO) robust against\ud high-frequency substrate noise, using as a demonstrator a 2.5 GHz VCO with quadrature outputs (QVCO) based on a 5-GHz LC tank resonant VCO (LC-VCO) and frequency divider. A simple, intuitive, and easy to handle analytical model is proposed to identify the design parameters that contribute to the performance degradation of LC-VCOs due to the\ud effect of high frequency substrate noise. The guidelines obtained have been applied in the design of the low-power QVCO. Finally, the work discusses several trade-offs that can be used to maximize the immunity of a LC-VCO against substrate noise.Peer ReviewedPostprint (published version

Micromachined substrate slots for RF on-chip isolation

“…Modern wireless systems require all building components to be integrated on a single chip for low cost and high reliability, particularly in CMOS technology. For mobile communications, most RF circuit blocks are currently integrated with analog and digital components in CMOS [1][2][3]. However, the power amplifier (PA) still remains the most challenging block to design in CMOS due to its low breakdown voltage and high substrate loss.…”

“…This problem appears even more seriously when the signal is in RF range, as the signal at the high frequency tends to couple to the substrate more easily through the capacitance and interferes with other circuits. The interferences can cause problems that degrade the RFIC performance, such as selfmixing of receiver and signal pulling of the VCO . Strategies to reduce the substrate signal problem have been reported, including using substrate contacts as a guard ring (Fig.…”