Patent ID: 8207777
Filing Date: 2012-06-26
Classification: H03G

Abstract:
1. An RF measurement circuit comprising: a ratiometric gain/attenuator circuit having a first gain stage and a ratiometric attenuator; a first detector cell having an input coupled to an output of the ratiometric gain/attenuator circuit; a second detector cell having an input coupled to an input of the ratiometric gain/attenuator circuit; a nulling circuit having a first input coupled an output of the first detector cell and a second input coupled to an output of the second detector cell; and an RF gain stage having an output coupled to the input of the ratiometric gain/attenuator circuit; where the nulling circuit is arranged to force the value of an output signal from the first detector cell to equal the value of an output signal from the second detector cell; and where the nulling circuit has an output arranged in a feedback configuration to control the combined gain of the first gain stage and the RF gain stage, thereby stabilizing the gain of the RF gain stage by forcing the gain to a value determined by a ratio of component values in the ratiometric attenuator.