Memristor-Based Loop Filter Design for Phase Locked Loop

Naheem Olakunle Adesina,Ashok Srivastava

doi:10.3390/jlpea9030024

Naheem Olakunle Adesina, Ashok Srivastava

Open Access

https://doi.org/10.3390/jlpea9030024

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Abstract

The main challenge in designing a loop filter for a phase locked loop (PLL) is the physical dimensions of the passive elements used in the circuit that occupy large silicon area. In this paper, the basic features of a charge-controlled memristor are studied and the design procedures for various components of a PLL are examined. Following this, we propose a memristor-based filter design which has its resistance being replaced by a memristor in order to reduce the die area and achieve a low power consumption. We obtained a tuning range of 741–994 MHz, a stable output frequency of 1 GHz from the transfer characteristics of voltage-controlled oscillator (VCO), and an improved settling time. In addition to reduced power consumption and area occupied on the chip, our design shows a high reliability over wider range of temperature variations.

Highlights

A phase locked loop (PLL) is a mixed-signal feedback system which consists of both analog and digital blocks including the loop filter
Though studies have shown that a voltage-controlled oscillator (VCO) is the most important component of a PLL, the loop filter is important because it removes remaining high frequency components in the output of the charge pump and stabilizes the control input to the VCO
Desirable to improve the performance of the phase locked loop in terms of its power consumption, tuning range, reliability, lock time, phase noise etc. [1,2,3]

Summary

Introduction

A phase locked loop (PLL) is a mixed-signal feedback system which consists of both analog and digital blocks including the loop filter. It is highly notable that PLL applications, in the fields of communications, control systems and power electronics have evolved greatly in recent times This complements the fact that the PLL is an old technology, it has proven to be relevant in current trend devices and for future technological advancements. Memristors’ ability to maintain a state without requiring external biasing can significantly reduce overall power consumption, while the deep-nanoscale physical dimensions of the device (minimum reported: 5 × 5 nm) are ideal for its implementation in the field of VLSI (very large-scale integration) [5] and can provide a much-needed extension to Gordon Moore’s law Emerging devices, such as memristors, when compared with established elements, tend to manifest advanced properties and often exhibit novel characteristics that can be exploited for enhancing the performance of conventional circuitry (e.g., a loop filter) as well as developing novel designs and applications. Many memristor-based analog applications have been presented since the announcement of the Helwett

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