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UBC Theses and Dissertations

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UBC Theses and Dissertations

On the design of type-i integer-n phase-locked loops Sharkia, Ahmad

Abstract

The phase-locked loop (PLL) is an essential building block of modern communication and computing systems. In a wireless communication system, a PLL is almost always used as the local oscillator (LO) that synthesizes the required frequency for data transmission and reception. In wireline and optical communication systems, PLL-based clock and data recovery (CDR) circuits are often employed for the extraction of the clock signal from the incoming data signal, and aligning the recovered clock edge with the incoming data for optimal bit-error rate (BER) performance. Furthermore, in microprocessor and field-programmable gate array (FPGA) systems, PLLs are typically used for clock generation. Although phase-locking is a very mature research topic, its continuous application in modern integrated circuits (ICs) and systems, requires continuous improvement in its performance, power consumption, and manufacturing costs. Analog Type-II PLLs are among the most widely used category of PLLs in CMOS (complementary-metal-oxide-semiconductor) ICs, mainly due to their robustness, superior performance and their well-established theory. However, analog Type-II PLLs require a large area in loop-filter (LF) and employ noisy and difficult-to-design charge-pumps (CPs). All-digital PLLs are also widely used, but they suffer from the strict jitter requirements on time-to-digital converters (TDCs). We propose a Type-I PLL that uses a small LF area, does not require bias-generation circuits or CP, and consumes low power. A pulse-width-modulated (PWM) voltage output from the phase-frequency detector (PFD) is fed to a simple RC single-pole LF. Two major limitations of conventional Type-I topologies – limited lock-range and large reference spur – are overcome by increasing the PFD gain with a combination of a voltage booster and a digital level shifter, and a sample-and-hold (S/H) envelope detector, respectively. Furthermore, a saturated-PFD (SPFD) is proposed to reduce cycle slipping and to further improve the lock-range and lock-time. A proof-of-concept prototype 2.2-to-2.8 GHz PLL occupies a core area of 0.12 mm² in 0.13-μm CMOS and achieves 490 fsrms random jitter, -103.4 dBc/Hz in-band phase-noise, -65 dBc reference spur, 2.5 μs worst-case lock-time while consuming 6.8 mW from a 1.2 V supply.

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Attribution-NonCommercial-NoDerivs 2.5 Canada