The AD8309 can provide a large voltage gain combined with
progressivecompression, through which an IF signal of high dynamic range is
converted into a square-wave (that is, hard limited)output, from which
frequency and phase information modulated on this input can be recovered by
subsequent signal processing. For this purpose, the noise level referred to the
input must very low, since it determines the detection threshold for the
Refer to the datasheet on page 2 for more details on the limiter amplifier.