In this paper, we exemplify the power reduction that can be achieved by using analogue rather than digital signal processing. This reduction is illustrated with an FSK demodulation. The power reduction is achieved using conventional off-the-shelf discrete electronics components rather than through an ASIC implementation. The power consumption is reduced by a factor of more than ten; more specifically, the analogue FSK demodulator consumes about 65 μW compared to 750 μW for the digital implementation. These results show that analogue signal processing is an interesting candidate for power optimisation, even in cases where an ASIC is not practical.