A Single-VCO Fractional-$N$ Frequency Synthesizer for Digital TV Tuners

A single-voltage-controlled-oscillator (VCO) fractional-N frequency synthesizer is designed for Advanced Television Systems Committee, Digital Video Broadcasting-Terrestrial, and Integrated Services Digital Broadcasting-Terrestrial digital television tuners. This frequency synthesizer can cover all the frequency bands for all three standards with only one VCO, and thus, the chip area as well as the power consumption can be greatly reduced. Different channel spacing requirements can be fulfilled by fractional synthesis. A dynamic frequency calibration loop is also used to automatically choose the coarse setting of the VCO. The synthesizer was fabricated in a standard 0.13-μm complementary metal-oxide-semiconductor process and draws 14 mA from a 1.2-V supply. The measured phase noise is lower than -80 dBc/Hz from 1 to 100 kHz offset and -100 dBc/Hz at 1 MHz offset. The active area of the frequency synthesizer is smaller than 0.54 mm².

I. Introduction

The digital television (DTV) standard has ushered in a new era in television (TV) entertainment. Since the DTV not only utilizes the frequency band more efficiently, but also provides the audience better experience of watching TV, many countries all over the world have planned to move their TV broadcasting systems from analog to digital in the near future and have announced their choice for a DTV standard [1]. Currently, the following three major DTV standards are adopted: Advanced Television Systems Committee (ATSC), Digital Video Broadcasting-Terrestrial (DVB-T), and Integrated Services Digital Broadcasting-Terrestrial (ISDB-T). The main characteristics of them are listed in Table I. Table I DTV Standards

	ATSC	DVB-T	ISDB-T
Area	North America	Europe, Australia, Taiwan	Japan
Frequency Bands (MHz)	55.25 to 855.25	174 to 230	90 to 108
		470 to 862	170 to 222
			470 to 770
Channel (MHz)	6	6, 7, 8	6, 3/7
Modulation	8-VSB, 16-VSB	COFDM, QPSK, 16QAM, 64QAM	BST-OFDM, QPSK, 16QAM, 64QAM