An envelope detection circuit includes a signal rectifier, first and
second capacitors, and first, second and third transistors. The signal
rectifier includes an input port coupled to receive a modulated input
signal, and an output port. The first capacitor has a first port coupled
to the output port of the signal rectifier and a second port for coupling
to a signal ground. The first transistor has a first port coupled to the
output port of the signal rectifier, a second port for coupling to a
signal ground, and a control port. The second transistor has a first port
for coupling to a power supply, a second port, and a control port coupled
to the output of the signal rectifier. The third transistor has a first
port coupled to second port of the second transistor, a second port for
coupling to a signal ground, and a control port. The second capacitor has
a first port coupled to first port of the third transistor, and a second
port for coupling to a signal ground.