An RF detector with a dynamic range of 40 dB can now be obtained from Linear Technology (http://www.lineartech.com/pdf/5505i.pdf).
The type LTC5505, housed in a SOT23 SMD package can handle input frequencies between300 MHz and 3 GHz for input signal levels between –32 dBm and +18 dBm (0 dBm = 1 mW into 50 Ω). There are two versions
having different input level ranges, as shown in the table.
The LTC5505-1 is intended to be used for the upper range of signal levels. A series input resistor (Rin) in combination with the internal input resistance attenuates the input signal. For both versions, the input impedance is approximately 50 Ω. The LTC5505 contains a Schottky diode used as a detector, which is temperature compensated by additional circuitry. The IC requires an operating current of only 0.5 mA at a supply voltage between +2.7 V and +6 V. An active-Low shutdown input can be used to disable the detector.
In the disabled state, the IC draws less than 2 μA. The output voltage of the detector ranges from +280 mV to more than +2 V, depending on the input signal level, with a load current capacity of around 1 mA. Again compression block reduces the output level at high RF levels in order to keep the output signal within the stated range, whose upper limit is set by the minimum supply voltage of +2.7 V. Using this detector IC, simple diode detectors can be replaced by a component of the same size having significantly better characteristics.