Building an RF Power Meter

Here is yet another AD8307 based RF power meter which adds an opamp to produce a DC output voltage of 1mV/dBm (e.g., 0mV = 0dBm, -10mV = -10dBm, etc). The RF power in dBm can be read directly with a multimeter, and I’ve found it particularly useful for measuring RF filter response when combined with a sweep generator and an oscilloscope:

Visualizing a 6MHz Low Pass Filter Response over 1-11MHz (10dBm/div)

Visualizing a 6MHz Low Pass Filter Response over 1-11MHz (10dBm/div)

The AD8307’s high dynamic range and good accuracy over a wide bandwidth make it especially useful if, like me, you don’t own a spectrum analyzer which would otherwise be ideal for filter measurements.

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