RF impedance measurement circuit
AssigneeIM EC vzw
InventorsYang Zhang, Pierre Wambacq
Life of this patent
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Abstract
An RF impedance measurement circuit includes a sensing capacitor connectable with an RF signal path; a first amplitude detector and a first frequency divider, each coupled, with the measurement circuit in operation, to the RF signal path at a first terminal of the sensing capacitor; a second amplitude detector and a second frequency divider, each coupled, with the measurement circuit in operation, to a second terminal of the sensing capacitor; and a phase detection circuit connected to an output of the first frequency divider and to an output of the second frequency divider.
Claims20
An RF impedance measurement circuit comprising:
- a sensing capacitor having a first terminal and a second terminal;
- a first amplitude detector coupled to the first terminal and configured to detect a first amplitude of a first input signal having a first oscillation frequency;
- a first frequency divider coupled to the first terminal, wherein the first frequency divider is configured to receive the first input signal and generate a first output signal having a second oscillation frequency, wherein the first oscillation frequency is an integer multiple of the second oscillation frequency;
- a second amplitude detector coupled to the second terminal and configured to detect a second amplitude of a second input signal having a third oscillation frequency;
- a second frequency divider coupled to the second terminal, wherein the second frequency divider is configured to receive the second input signal and generate a second output signal having a fourth oscillation frequency, wherein the third oscillation frequency is an integer multiple of the fourth oscillation frequency;
- and
- a phase detection circuit configured to detect a phase difference between the first terminal and the second terminal based on the first output signal and the second output signal;
- and
- a processing unit configured to calculate a load impedance of an RF signal path that includes the sensing capacitor based on the first amplitude, the second amplitude, and the phase difference.
A method of RF impedance measurement, the method comprising:
- detecting a first amplitude of a first input signal having a first oscillation frequency at a first amplitude detector coupled to a first terminal of a sensing capacitor;
- receiving the first input signal via a first frequency divider;
- generating, via the first frequency divider, a first output signal having a second oscillation frequency, wherein the first oscillation frequency is an integer multiple of the second oscillation frequency;
- detecting a second amplitude of a second input signal having a third oscillation frequency at a second amplitude detector coupled to a second terminal of the sensing capacitor;
- receiving the second input signal via a second frequency divider;
- generating, via the second frequency divider, a second output signal having a fourth oscillation frequency, wherein the third oscillation frequency is an integer multiple of the fourth oscillation frequency;
- detecting a phase difference between the first terminal and the second terminal based on the first output signal and the second output signal, wherein an input of the first frequency divider is coupled to the first terminal and an input of the second frequency divider is coupled to the second terminal;
- and
- calculating a load impedance of an RF signal path that includes the sensing capacitor based on the first amplitude, the second amplitude, and the phase difference.
Dependencies are inferred from the claim text.