Patent ID: 9140733
Filing Date: 2015-09-22
Classification: G01R

Abstract:
1. A detector circuit for determining a reflection coefficient, the detector circuit comprising: a signal port; a load port; a signal path coupled between the signal port and the load port; a bidirectional directional coupler, wherein the bidirectional directional coupler is connected to the signal path and makes a first signal available at a first output, the first signal comprising a measure of power transmitted in a forward direction in the signal path, the bidirectional directional coupler making a second signal available at a second output, the second signal comprising a measure of power transmitted counter to the forward direction in the signal path; a first logarithmic amplifier, wherein the first logarithmic amplifier is coupled to the first output and is configured to logarithmically amplify the first signal; a second logarithmic amplifier, wherein the second logarithmic amplifier is coupled to the second output and is configured to logarithmically amplify the second signal; and a subtractor comprising a differential amplifier and having an offset connection provided through a resistance coupled to a first differential input of the differential amplifier, wherein the first differential input of the differential amplifier is coupled to an output of the first logarithmic amplifier, and a second differential input of the differential amplifier is coupled to an output of the second logarithmic amplifier, wherein the subtractor is configured to determine a difference from the first logarithmically amplified signal and the second logarithmically amplified signal as a measure of the reflection coefficient, and wherein an offset voltage is present between ground and the offset connection of the subtractor.