RMS power sensor with 84 dB dynamic range

摘要

A power meter includes components to measure RMS power over an 84 dB range or greater using the I-V square-law relation of a diode for measurements. The power meter includes multiple diodes along with a power distribution manifold which includes power dividers to distribute an input signal to the diodes. In one embodiment, a first power divider (202) distributes power to a first one of the diodes (203), and to the second power divider (204) which distributes power to the second (210) and third (212) diodes. The first power divider (202) is connected without attenuation to the first diode (203). The second power divider (204) is connected to the second diode (210) through a 11 dB attenuator (206), and to the third diode (212) through a 28 dB attenuator (208). With such attenuation, the first diode can operate in its square law range for measurements of signals with power from −64 dBm to −14 dBm, while the second diode can operate in its square law range for signals with power from −14 dBm to +3 dBm, and the third diode can operate within its square law range for signals with power from +3 dBm to +20 dBm. By measuring the current from the appropriate diode depending on the power level of the input signal, RMS power can be determined accurately over an 84 dB operating range. In an alternative embodiment, unequal power dividers (402) and (404) are used to distribute power and eliminate the need for attenuators (206) and (208) and to provide greater operating range sensitivity.