Balanced mixer with calibration of load impedances
A calibration device (CC) is coupled to a balanced circuit device (MC) comprising first and second outputs respectively provided with first (Z 1 ) and second (Z 2 ) load impedance means. This calibration device (CC) comprises adjusting means (ADM) arranged to adjust said first (Z 1 ) and second (Z 2 ) load impedance means into a load imbalance for linearization purposes, and a coupling means (CM) inserted between the load impedance adjusting means (ADM) and the first and second outputs and arranged to selectively couple the load impedance adjusting means (ADM) to only a chosen one of the first and second outputs, so that the load impedance adjusting means (ADM) is connected in parallel either to the first load impedance means (Z 1 ) or to the second load impedance means (Z 2 ).
1. Calibration device for a balanced circuit device comprising first and second outputs respectively provided with first and second load impedance means, said calibration device comprising adjusting means arranged to adjust said first and second load impedance means into a load imbalance for the purpose of linearization, characterized in that it comprises a coupling means inserted between said load impedance adjusting means and said first and second outputs and arranged to selectively couple said load impedance adjusting means to only a chosen one of said first and second outputs, so that said load impedance adjusting means is connected in parallel either to said first load impedance means or to said second load impedance means.
2. Calibration device according to claim 1 , characterized in that said coupling means comprises at least a first switching means inserted between said load impedance adjusting means and said first output and a second switching means inserted between said load impedance adjusting means and said second output, said first and second switching means being arranged to couple said load impedance adjusting means to only one of said first and second outputs at the same time.
3. Calibration device according to claim 2 , characterized in that said coupling means also comprises a third switching means comprising a first terminal coupled to said first output upstream of said first switching means and a fourth switching means comprising a first terminal coupled to said second output upstream of said second switching means said third switching means being arranged to be in an “off” state when said first switching means is in an “on” state, and said fourth switching means being arranged to be in an “off” state when said second switching means is in an “on” state, whereby each of said first and second outputs is always coupled to one switching means in its “on” state and one switching means in its “off” state.
4. Calibration device according to claim 3 , wherein said third and fourth switching means are dummy switching means each comprising a second terminal, said second terminals being coupled to each other.
5. Calibration device according to claim 3 , wherein said states of said first second third and fourth switching means are controlled by the same command signal.
6. Calibration device according to claim 1 , wherein said load impedance adjusting means comprises at least one adjusting element comprising a control switch means connected in series to an auxiliary load impedance means.
7. Calibration device according to claim 6 , wherein said load impedance adjusting means comprises at least two adjusting elements connected in parallel, each of said adjusting elements being selectable through command signals to adjust said first or second load impedance means to a chosen load imbalance.
8. Calibration device according to claim 6 , wherein each auxiliary load impedance means comprises one terminal coupled to said first and second switching means.
9. Calibration device according to claim 6 , wherein each of said auxiliary load impedance means differs from one adjusting element to another.
10. Balanced circuit device comprising first and second outputs respectively provided with first and second load impedance means, characterized in that it comprises a calibration device according to any one of the preceding claims, coupled to said first and second outputs.
11. Balanced circuit device according to claim 10 , characterized in that it is chosen in a group comprising a mixer circuit, a modulator circuit and a demodulator circuit.
12. Balanced circuit device according to claim 11 , characterized in that it constitutes a mixer circuit arranged in the form of a Gilbert-cell multiplier.
13. Receiver and/or transmitter device characterized in that it comprises at least one balanced circuit device according to claim 10 .
14. Receiver and/or transmitter device according to claim 13 , characterized in that it comprises a direct conversion receiver circuit.
15. Receiver and/or transmitter device according to claim 13 , characterized in that it comprises a low-intermediate frequency conversion receiver circuit.
16. Integrated circuit, characterized in that it defines at least one balanced circuit device according to claim 10 .
17. Integrated circuit, characterized in that it defines a receiver and/or transmitter circuit comprising at least one balanced circuit device according to claim 10 .