A study on low power PVT-robust delay locked loop: A subthreshold DLL-based clock generator with 90° I/Q signals for pulse-injection crystal oscillator application

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Volume Title

School of Electrical Engineering | Master's thesis

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Date

2025-11-19

Department

Major/Subject

Microelectronic Circuit Design

Mcode

Degree programme

Master's Programme in Electronics and Nanotechnology
Elektroniikan ja nanoteknologian maisteriohjelma
Magisterprogrammet i elektronik och nanoteknologi

Language

en

Pages

52

Series

Abstract

This paper presents the design of an ultra-low-power, Process, Voltage, and Temperature (PVT)-robust Delay-Locked Loop (DLL) based clock generator. The system is implemented in a 130 nm Complementary Metal–Oxide–Semiconductor (CMOS) process to generate 32.768 kHz In-phase/Quadrature (I/Q) clock signals for a Pulse-Injection Crystal Oscillator (PIXO) application. To achieve minimal power consumption, the entire circuit operates in the subthreshold region. The design addresses the significant challenge of device mismatch inherent in subthreshold operation through careful circuit topology choices and layout techniques. The proposed architecture includes a clock slicer using area-efficient series-parallel current mirrors, a supply-independent adaptive bias generator, and a novel Charge Pump (CP)-integrated quadrature Phase Detector (PD) that eliminates charge-coupling-induced current spikes. Simulation results demonstrate a total power consumption of 553.39 nW at 1.25 V at room temperature. The DLL achieves a startup time of 300 μs and maintains delay-time variations within –5.5% to +1% across a supply range of 1.1 V to 1.4 V and a temperature range of –40 °C to 90 °C, as well as ±18% (3σ) in Monte Carlo (MC) mismatch simulations, meeting the requirements for the target application.

Description

Supervisor

Kim, Kwantae

Thesis advisor

Sillanpää, Tero

Keywords

crystal oscillator, ultra low power, delay locked loop, I/Q signal generator, pulse-injection crystal oscillator, PVT-robust

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202512159185

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[dipl] Sähkötekniikan korkeakoulu / ELEC