Dynamic frequency divider circuit
The invention relates to a Frequency Divider Circuit for dividing an input RF signal to a frequency divided RF signal. The circuit comprises a RF pair, a switching-quad pair coupled in series with a transimpedance amplifier and a double pair of emitter followers. The circuit comprises coupling elements for providing first DC paths to first amplifier paths of the RF pair and for providing second DC paths to second amplifier paths of the series arrangement of the switching-quad pair and the transimpedance amplifier. The first DC paths are independent of the second DC paths. RF connections are provided to couple the first and the second amplifier paths for transferring a signal from the first amplifier paths to the second amplifier paths.
1. A dynamic frequency divider circuit for operating in a mm-wave band and for dividing an input RF signal to a frequency divided RF signal, the dynamic frequency divider circuit comprising:
an RF pair comprising a differential pair of first amplifier elements and first differential control terminals for receiving the input RF signal, the differential pair comprising first amplifier paths being response to the input RF signal;
a switching-quad pair comprising a double differential pair of second amplifier elements in a cross-coupled arrangement and second differential control terminals for receiving a feedback signal, wherein the double differential pair comprises double second amplifier paths responsive to the feedback signal, and the switching-quad pair comprises differential output terminals connected with the double second amplifier paths;
a transimpedance amplifier coupled in series with the switching-quad pair and configured to amplify the signal of the differential output terminals;
a double pair of emitter followers configured to buffer the amplified signal received from the transimpedance amplifier, wherein the double pair of emitter followers comprises follower input terminals configured to receive the amplified signal from the transimpedance amplifier and further comprising output terminals for providing the feedback signal and the frequency divided RF signal;
DC voltage supply rails;
first coupling elements configured to provide the first amplifier paths with a first DC connection between the DC voltage supply rails;
second coupling elements configured to provide the double second amplifier paths with a second DC connection between the DC voltage supply rails, wherein the second DC connection being parallel to the first DC connection; and
RF connections between the first amplifier paths and double second amplifier paths configured to transfer a RF signal from the first amplifier paths to the double second amplifier paths.
2. The dynamic frequency divider circuit according to claim 1 , wherein the first coupling elements comprise RF chokes being coupled between the RF pair and a first one of the DC voltage supply rails.
3. The dynamic frequency divider circuit according to claim 2 , wherein the first coupling elements comprise transmission lines being coupled between the RF pair and the first one of the DC voltage supply rails.
4. The dynamic frequency divider circuit according to claim 3 , wherein
the RF chokes comprise a first terminal and a second terminal,
the transmission lines comprise a first terminal and a second terminal,
the RF chokes are connected with the first terminal to the first one of the DC voltage supply rails, and
the transmission lines are connected with the first terminal to the second terminal of the RF chokes and with the second terminal to the RF pair.
5. The dynamic frequency divider circuit according to claim 2 , wherein the RF chokes are transmission lines of a length substantially equal to a quarter wavelength of a fundamental frequency of the input RF signal.
6. The dynamic frequency divider circuit according to claim 1 , wherein the second coupling elements comprise RF chokes being coupled between the switching-quad pair and a second one of the DC voltage supply rails.
7. The dynamic frequency divider circuit according to claim 6 , wherein the second coupling elements comprise transmission lines being coupled between the switching-quad pair and the second one of the DC voltage supply rails.
8. The dynamic frequency divider circuit according to claim 7 , wherein
the RF chokes comprise a first terminal and a second terminal,
the transmission lines comprise a first terminal and a second terminal,
the RF chokes are connected with the first terminal to the second one of the DC voltage supply rails, and
the transmission lines are connected with the first terminal to the second terminal of the RF chokes and with the second terminal to the switching quad pair.
9. The dynamic frequency divider circuit according to claim 8 , wherein the RF chokes are transmission lines of a length substantially equal to a quarter wavelength of a fundamental frequency of the input RF signal.
10. The dynamic frequency divider circuit according to claim 1 , wherein the RF connections comprise DC isolation elements for isolating a DC voltage of the first amplifier paths from a DC voltage of the double second amplifier paths.
11. The dynamic frequency divider circuit according to claim 10 , wherein the DC isolating elements comprise a capacitor.
12. The dynamic frequency divider circuit according to claim 11 , wherein the capacitor is a mim capacitor.
13. The dynamic frequency divider circuit according to claim 1 , wherein the RF connections comprise transmission lines being coupled between the first amplifier paths and the double second amplifier paths.
14. The dynamic frequency divider circuit according to claim 13 , wherein each RF connection comprises two transmission lines coupled in series.
15. The dynamic frequency divider circuit according to claim 14 , wherein the DC isolation element of a single RF connection is arranged in between and coupled to the two transmission lines.
16. The dynamic frequency divider circuit according to claim 15 , wherein the transmission lines are configured to match an output impedance of an amplifier formed by the RF pair to an input impedance of a closed looped mixer comprising the switching-quad pair, transimpedance amplifier and the double pair of emitter followers.
17. A semiconductor device comprising a dynamic frequency divider circuit for operating in a mm-wave band and for dividing an input RF signal to a frequency divided RF signal, the dynamic frequency divider circuit comprising:
an RF pair comprising a differential pair of first amplifier elements and comprising first differential control terminals for receiving the input RF signal, the differential pair comprising first amplifier paths being response to the input RF signal;
a switching-quad pair comprising a double differential pair of second amplifier elements in a cross-coupled arrangement and comprising second differential control terminals for receiving a feedback signal, the double differential pair comprising double second amplifier paths being responsive to the feedback signal, the switching-quad pair comprising differential output terminals connected with the double second amplifier paths;
a transimpedance amplifier being coupled in series with the switching-quad pair and being configured to amplify the signal of the differential output terminals;
a double pair of emitter followers for buffering the amplified signal received from the transimpedance amplifier, the double pair of emitter followers comprising follower input terminals for receiving the amplified signal from the transimpedance amplifier and comprising output terminals for providing the feedback signal and the frequency divided RF signal;
DC voltage supply rails;
first coupling element for providing the first amplifier paths with a first DC connection between the DC voltage supply rails;
second coupling elements for providing the double second amplifier paths with a second DC connection between the DC voltage supply rails, the second DC connection being parallel to the first DC connection; and
RF connections between the first amplifier paths and double second amplifier paths for transferring a RF signal from the first amplifier paths to the double second amplifier paths.
18. A radar system comprising a dynamic frequency divider circuit for operating in a mm-wave band and for dividing an input RF signal to a frequency divided RF signal, the dynamic frequency divider circuit comprising:
an RF pair comprising a differential pair of first amplifier elements and comprising first differential control terminals for receiving the input RF signal, the differential pair comprising first amplifier paths being response to the input RF signal;
a switching-quad pair comprising a double differential pair of second amplifier elements in a cross-coupled arrangement and comprising second differential control terminals for receiving a feedback signal, the double differential pair comprising double second amplifier paths being responsive to the feedback signal, the switching-quad pair comprising differential output terminals connected with the double second amplifier paths;
a transimpedance amplifier being coupled in series with the switching-quad pair and being configured to amplify the signal of the differential output terminals;
a double pair of emitter followers for buffering the amplified signal received from the transimpedance amplifier, the double pair of emitter followers comprising follower input terminals for receiving the amplified signal from the transimpedance amplifier and comprising output terminals for providing the feedback signal and the frequency divided RF signal;
DC voltage supply rails;
first coupling element for providing the first amplifier paths with a first DC connection between the DC voltage supply rails;
second coupling elements for providing the double second amplifier paths with a second DC connection between the DC voltage supply rails, the second DC connection being parallel to the first DC connection; and
RF connections between the first amplifier paths and double second amplifier paths for transferring a RF signal from the first amplifier paths to the double second amplifier paths.