An 8–12.5-GHz LC PLL with Dual VCO and Noise-Reduced LDO Regulator for Multilane Multiprotocol SerDes in 28-nm CMOS Technology

Abstract

This study presents an inductance capacitance (LC) phase-locked loop (PLL) with a dual voltage-controlled oscillator (VCO) and a noise-reduced low-dropout (LDO) regulator, which was used in four-lane multiprotocol serial link applications. The dual VCO architecture can increase the total frequency-tuning range to ensure that the LC PLL achieves multiprotocol serial link coverage from 8 to 12.5 Gbps. Two switch capacitor array-based LC VCOs have a large frequency-tuning range and small VCO gain. The noise-reduced LDO regulator provides a very low-noise power supply to the VCO. The active area occupied by the proposed LC PLL in UMC 28-nm 1P10M complementary metal–oxide–semiconductor (CMOS) technology is 0.25 mm2. The phase noise of the VCO at 1 MHz is −108.1 dBc/Hz. The power consumption of the LC PLL with a 1.8-V supply is 16.5 mW.

An 8-Gbps, Low-Jitter, Four-Channel Transmitter with a Fractional-Spaced Feed-Forward Equalizer

“…The CP uses two rail-to-rail operational amplifiers to reduce the drain-voltage fluctuations in the metal-oxide-semiconductor field-effect transistor (MOSFET) in the current supply, with the goal of mitigating the mismatch between the charge and discharge currents introduced by channel-length modulation [16]. Moreover, a ring VCO architecture is adopted to reduce the chip area and cost, while providing a broadband tuning range [17]. The PD and OD divide the frequency of the reference and output clocks, respectively, to expand the output frequency band of the PLL [18].…”

Design of a fully integrated VHF CP‐PLL frequency synthesizer with an all‐digital defect‐oriented built‐in self‐test

“…The VCO generates an output signal based on the input reference clock. VCOs used in PLL frequency synthesizers are commonly realized with LC ‐tanks [1, 2] or ring topologies [3, 4]. Generally, LC‐VCOs consist of an inductor L and voltage‐tunable capacitor C forming a parallel tank which oscillates at $$\frac{1}{{2\pi \sqrt {LC} }}$$.…”

A Single-Event Transient Radiation Hardened Low-Dropout Regulator for LC Voltage-Controlled Oscillator

“…Therefore, the conventional design of VCO is focused on noise suppression of the power supply. A low-dropout regulator (LDO) is a common method to provide high-quality power supply to the VCO [6,7].…”