A de-spreading device for a spread spectrum communication system includes
a first and a second correlator assigned to a regular and a power-saving
operation mode, respectively. The first correlator performs sampling with
a regular operational clock while the second correlator performs sampling
with an operational clock higher in rate than the regular operational
clock for thereby saving power. The regular or the power-saving operation
mode is selected in accordance with radio channel quality estimated on
the basis of a peak value detected from a correlation value, which is
output from the first or the second correlator. De-spreading can
therefore be implemented by an optimum operational clock matching with
radio channel quality while consuming a minimum of current.