Bandpass ΔΣ ADCs for Wireless Receivers
Richard Schreier and Hajime Shibata, Analog Devices, Inc. Toronto, Canada
Since ADCs were first tacked onto the end of a wireless receiver’s signal chain the boundary between analog and digital processing has shifted steadily toward the antenna. As depicted in Figure 8.1, lowpass ADCs with bandwidths in the kHz range were initially used to digitize a single channel at baseband. Later, bandpass and subsampling ADCs did likewise at IF and, as the bandwidth and dynamic range of the ADCs improved, receivers increasingly relied upon digital signal processing to perform channel filtering. Nowadays, ADCs can digitize a 100 MHz swath of spectrum with sufficient dynamic range that multi-carrier ...