Ultra-Wideband Modulation Signal Measurement Using Local Sweep Digitizing Method

Recently, bandwidth for wireless communications are getting wider, i.e. 400 MHz for the 5th generation mobile communication (5G), and about 2 GHz for wireless LAN (IEEE 802.11ad). To evaluate the transceiver devices used in these communications, a high-speed waveform digitizer is required. In this paper, the "Local Sweep Digitizing Method" which accurately captures ultra-wideband signals covering 2 GHz with low cost is introduced. It is a method of decomposing a wideband signal transmitted at a high frequency into subband signals of several hundred megahertz bandwidths while downconverting it to an intermediate frequency, and capturing it for each subband signal by a low speed waveform digitizer. The captured waveform is synthesized by post digital processing. At this time, a correction process for matching the carrier phase and the conversion gain of each subband signal is performed. In this method, an ultra-wideband signal can be captured by a single low-speed high-resolution analog-to-digital converter (ADC) and the measurable bandwidth can be easily controlled by adjusting the Local Sweep section.