RF switch with split tunable matching network
An improved architecture for a radio frequency (RF) power amplifier, impedance matching network, and selector switch. One aspect of embodiments of the invention is splitting the functionality of a final stage impedance matching network (IMN) into two parts, comprising a base set of off-chip IMN components and an on-chip IMN tuning component. The on-chip IMN tuning component may be a digitally tunable capacitor (DTC). In one embodiment, an integrated circuit having a power amplifier, an on-chip IMN tuner, and a selector switch is configured to be coupled to an off-chip set of IMN components. In another embodiment, an integrated circuit having an on-chip IMN tuner and a selector switch is configured to be coupled through an off-chip set of IMN components to a separate integrated circuit having an RF power amplifier.
1. A radio frequency (RF) integrated circuit chip including:
(a) a selector switch including an input port and at least one output port;
(b) an impedance matching network (IMN) tuner coupled to the input port of the selector switch and configured to be coupled to an off-chip set of IMN components, the IMN tuner including at least one digitally tunable capacitor including a stack of field effect transistors configured to withstand applied high voltage signals; and
(c) a control circuit, coupled to at least the IMN tuner, configured to provide tuning values for the at least one digitally tunable capacitor;
wherein the IMN tuner and the off-chip set of IMN components together comprise an impedance matching network.
2. The invention of claim 1 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resonant frequency from parasitic inductance is more than about twice the operating frequency of the integrated circuit.
3. The invention of claim 1 , further including a DC blocking capacitor coupled between the IMN tuner and the selector switch, and wherein the IMN tuner, the selector switch, and the DC blocking capacitor are integrated in close enough proximity such that the resonant frequency from parasitic inductance is more than about twice the operating frequency of the integrated circuit.
4. The invention of claim 1 , wherein the control circuit is configured to provide tuning values for the at least one digitally tunable capacitor in response to applied control signals or words.
5. The invention of claim 1 , wherein the control circuit is configured to provide tuning values for the at least one digitally tunable capacitor as a function of one of one or more of a user state selection, external control signals provided through a digital interface, and one or more detected system states or parameters.
6. The invention of claim 1 , wherein the control circuit is configured to provide tuning values for the at least one digitally tunable capacitor by means of a feed-forward loop and/or a feed-back loop to dynamically adjust the tuning values as a function of one of one or more of a user state selection, external control signals provided through a digital interface, and one or more detected system states or parameters.
7. The invention of claim 1 , wherein the control circuit is coupled to the selector switch and configured to select a signal route from the input port to a selected one of the at least one output port.
8. The invention of claim 1 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resulting parasitic inductance is less than about 1.0 nH.
9. The invention of claim 1 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resulting parasitic inductance is less than about 0.5 nH.
10. The invention of claim 1 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resulting parasitic inductance is about 0.1 nH or less.
11. A radio frequency (RF) integrated circuit chip including:
(a) a selector switch including an input port and a plurality of output ports, the selector switch configured to route an RF signal applied to the input port as an RF output signal on at least one selected output port;
(b) an impedance matching network (IMN) tuner coupled to the input port of the selector switch and configured to be coupled to an off-chip set of IMN components, the IMN tuner including at least one digitally tunable capacitor including a stack of at least two field effect transistors coupled in series to withstand applied high voltage signals; and
(c) a control circuit, coupled to at least the IMN tuner, configured to provide tuning values for the at least one digitally tunable capacitor;
wherein the IMN tuner and the off-chip set of IMN components together comprise an impedance matching network.
12. The invention of claim 11 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resonant frequency from parasitic inductance is more than about twice the operating frequency of the integrated circuit.
13. The invention of claim 11 , further including a DC blocking capacitor coupled between the IMN tuner and the selector switch, and wherein the IMN tuner, the selector switch, and the DC blocking capacitor are integrated in close enough proximity such that the resonant frequency from parasitic inductance is more than about twice the operating frequency of the integrated circuit.
14. The invention of claim 11 , wherein the control circuit is configured to provide tuning values for the at least one digitally tunable capacitor as a function of one of one or more of a user state selection, external control signals provided through a digital interface, and one or more detected system states or parameters.
15. The invention of claim 11 , wherein the control circuit is configured to provide tuning values for the at least one digitally tunable capacitor by means of a feed-forward loop and/or a feed-back loop to dynamically adjust the tuning values as a function of one of one or more of a user state selection, external control signals provided through a digital interface, and one or more detected system states or parameters.
16. The invention of claim 11 , wherein the control circuit is coupled to the selector switch and configured to select a signal route from the input port to the at least one selected output port.
17. The invention of claim 11 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resulting parasitic inductance is less than about 1.0 nH.
18. The invention of claim 11 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resulting parasitic inductance is less than about 0.5 nH.
19. The invention of claim 11 , wherein the IMN tuner and the selector switch are integrated in close enough proximity such that the resulting parasitic inductance is about 0.1 nH or less.
20. A method for impedance matching a radio frequency (RF) signal to a coupled selector switch, including:
(a) fabricating an integrated circuit having an impedance matching network (IMN) tuner and a selector switch coupled to the IMN tuner;
(b) positioning the IMN tuner and the selector switch on the integrated circuit in close enough proximity such that the resonant frequency from parasitic inductance is more than about twice the operating frequency of the integrated circuit;
(c) coupling the IMN tuner to an off-chip set of IMN components configured to receive the RF signal; and
(d) configuring the IMN tuner and the off-chip set of IMN components as an impedance matching network for the received RF signal.