A circuit arrangement for detecting a received signal includes a rectifier
with an input connected to a receiving antenna for rectifying an encoded
received signal, a signal capacitor connected to an output of the
rectifier, a discharge current sink connected to the signal capacitor,
and a signal evaluating circuit connected to the signal capacitor. The
discharge current sink includes a current mirror circuit of
cascode-connected transistors. Thereby, the discharge current is
substantially independent of the signal voltage over a larger range of
voltages. This signal detection circuit is useful in transponders or
remote sensors that receive and detect a signal transmitted by a base
station.