  The Graphics Processing Unit (GPU) has become an integral part of
astronomical instrumentation, enabling high-performance online data reduction
and accelerated online signal processing. In this paper, we describe a
wide-band reconfigurable spectrometer built using an off-the-shelf GPU card.
This spectrometer, when configured as a polyphase filter bank (PFB), supports a
dual-polarization bandwidth of up to 1.1 GHz (or a single-polarization
bandwidth of up to 2.2 GHz) on the latest generation of GPUs. On the other
hand, when configured as a direct FFT, the spectrometer supports a
dual-polarization bandwidth of up to 1.4 GHz (or a single-polarization
bandwidth of up to 2.8 GHz).
