1. Field of the Invention
The present invention relates to an analog-to-digital conversion method and apparatus, and more particularly to an analog-to-digital conversion method and apparatus that are capable of reducing the quantization distortion of a received signal in a receiver supporting multi-standard radios in which digital signal processing is performed in different ways from each other.
2. Description of the Related Art
In general, an Analog-to-Digital Converter (hereinafter referred to as “ADC”) refers to a device for converting an analog input signal into a digital signal. Various communication equipment or measuring equipment requiring digital signal processing require an ADC in order to perform signal conversion. One such typical communication equipment using the ADC is a receiver of a wireless communication system, such as a cellular phone, a mobile Internet terminal (hereinafter referred to as “mobile terminal) and the like. The ADC is placed between an RF end and a digital signal processing end of a mobile terminal so as to convert an input analog signal into a digital signal.
A Software Defined Radio (hereinafter referred to as “SDR”), which has recently come into notice as a next-generation platform for wireless communication, aims at supporting various standards such as a Wireless Local Area Network (WLAN), a Wireless Personal Area network (WPAN), etc. by installing or downloading software complying to a corresponding standard, instead of replacing hardware. In a transceiver such as an SDR system, digital processing of a received signal must be carried out pursuant to a corresponding radio standard.
Hereinafter, the SDR is discussed in more detail. The SDR refers to a technology for controlling the radio characteristics such as a frequency band, a modulation/demodulation scheme, output power, etc. of a transceiver, through new software installed or downloaded on the spot where a radio device is used without replacing hardware. In the existing wireless communication system, hardware must be replaced in order to change such radio characteristics, which involves a long time-to-market. Although the International Organization for Standardization of wireless communication has proposed various standards and recommended that every country adopt these standards, it is impossible to provide communication between 3G devices employing different standards.
Nevertheless, if radio characteristics such as frequency band, modulation/demodulation scheme, etc. can be controlled through the installation or download of software, it may be possible to provide communication between a mobile terminal and a base station by equipping them with such software even if they employ different radio standards. Further, it may be possible for a person carrying a SDR terminal to communicate anytime with those who carry devices employing different radio standards in other areas.
However, when such a SDR terminal receives a radio signal and converts it into a digital signal, it may be problematic in that a narrowband interference or Additive White Gaussian Noise (AWGN) may occur. On this account, an ADC provided in the SDR terminal must satisfy wideband signal processing, a high sampling rate, good resolution, low quantization distortion and the like in order to enable flexible digital signal processing. Therefore, there is a desire to develop an ADC capable of ensuring good performance to a SDR terminal.