From the viewpoint of power consumption, some systems with fast A/D converter (ADC) + long program are changing to slow ADC with analog preprocessor, plus shorter program. This paper proposes an analog correlator for such systems, where one series to correlate is stored in memory. The technique makes use of reconfigurability of a programmable switched-capacitor circuitry. A Fourier transformer prototyped on a commercial LSI is presented with experimental results, revealing that the method is advantageous in speed (3 times faster with the same power), as well as in power (27% less).