Coupled-line balun with common-mode nulling
AssigneeAnalog Devices, Inc.
InventorAndrew Pye
Life of this patent
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Abstract
Coupled-line baluns with common-mode compensation are provided herein. In certain configurations, a series resistor-inductor (RL) network is connected to ports of a coupled-line balun to null the common-mode transmission coefficient at a desired frequency. This extends performance at lower frequencies by improving the low frequency amplitude and phase balance of the device. The inductor and resistor can be connected in series between one of the differential terminals and a single-ended grounded terminal. This advantageously can null the common-mode transmission at a specific frequency near a minimum length-dominated frequency so as to enhance the common-mode rejection at lower frequencies.
Claims20
An electronic system with common-mode compensation, the electronic system comprising:
- a substrate;
- and
- a coupled-line balun over the substrate, wherein the coupled-line balun comprises:
- a first stripline including a first end configured to carry an unbalanced signal and a second end configured to carry a first component of a balanced signal;
- a second stripline adjacent to the first stripline and including a first end configured to receive a reference voltage and a second end configured to carry a second component of the balanced signal;
- and
- a series resistor-inductor (RL) network comprising a resistor and an inductor electrically connected in series between the second end of the first stripline and the reference voltage, wherein the series RL network is operable to control a common-mode response characteristic of the coupled-line balun.
A method of signal transformation with common-mode compensation, the method comprising:
- providing signal transformation using a coupled-line balun, including handling an unbalanced signal using a first terminal of the coupled-line balun, handling a first component of a balanced signal using a second terminal of the coupled-line balun, and handling a second component of the balanced signal using a third terminal of the coupled-line balun;
- receiving a reference voltage for the unbalanced signal at a fourth terminal of the coupled-line balun;
- and
- controlling a common-mode response of the coupled-line balun using a series resistor-inductor (RL) network connected between the second terminal and the fourth terminal.
A coupled-line balun with common-mode compensation, the coupled-line balun comprising:
- a first terminal configured to carry an unbalanced signal;
- a second terminal configured to carry a first component of a balanced signal;
- a third terminal configured to carry a second component of the balanced signal;
- a fourth terminal configured to receive a reference voltage for the unbalanced signal;
- and
- a series resistor-inductor (RL) network electrically connected between the second terminal and the fourth terminal.
Dependencies are inferred from the claim text.