Multi-mode power management apparatus
A multi-mode power management apparatus is provided. In embodiments disclosed herein, the multi-mode power management apparatus can be configured to operate in different power management modes across a wide range of modulation bandwidth (e.g., 80 KHz to over 200 MHz). The multi-mode power management apparatus includes a power management integrated circuit (PMIC) and an envelope tracking integrated (ET) circuit (ETIC), which are implemented in separate dies. The PMIC is configured to generate a low-frequency current and a low-frequency voltage. The ETIC is configured to generate a pair of ET voltages. Depending on the power management mode, the multi-mode power management apparatus can selectively output one or more of the ET voltages and the low-frequency voltage to different stages (e.g., driver stage and output stage) of a power amplifier circuit, thus helping to maintain optimal efficiency and linearity of the power amplifier circuit across the wide range of modulation bandwidth.
1. A multi-mode power management apparatus comprising:
a power management integrated circuit (PMIC) configured to generate a low-frequency current and a low-frequency voltage;
an envelope tracking (ET) integrated circuit (ETIC) comprising:
a first node coupled to the PMIC;
a second node coupled to the first node via a multifunction circuit;
a first voltage circuit configured to generate a first ET voltage based on a first ET target voltage;
a second voltage circuit configured to generate a second ET voltage based on a second ET target voltage; and
a control circuit configured to:
cause the first node and the second node to output one or more of the first ET voltage, the second ET voltage, and the low-frequency voltage; and
cause the first node and the second node to output at least the low-frequency current; and
a multi-stage power amplifier circuit coupled to the first node and the second node and configured to amplify a radio frequency (RF) signal, wherein the first ET target voltage is delayed from the second ET target voltage to accommodate for a temporal delay inside the multi-stage power amplifier circuit.
2. The multi-mode power management apparatus of claim 1 wherein, in a first power management mode, the control circuit is further configured to:
cause the first node to output the first ET voltage and the low-frequency current; and
cause the second node to output the second ET voltage less than or equal to the first ET voltage and an adjusted low-frequency current proportional to the low-frequency current.
3. The multi-mode power management apparatus of claim 1 wherein, in a third power management mode, the control circuit is further configured to cause the first node and the second node to each output the first ET voltage and the low-frequency current.
4. The multi-mode power management apparatus of claim 1 wherein, in a second power management mode, the control circuit is further configured to cause the first node and the second node to each output the second ET voltage and the low-frequency current.
5. The multi-mode power management apparatus of claim 1 wherein, in a fourth power management mode, the control circuit is further configured to cause the first node and the second node to each output the low-frequency voltage and the low-frequency current.
6. The multi-mode power management apparatus of claim 1 , wherein the multi-stage power amplifier circuit comprises a driver stage coupled to the second node and an output stage coupled to the first node, the first ET target voltage is delayed from the second ET target voltage to thereby accommodate for the temporal delay between the driver stage and the output stage.
7. The multi-mode power management apparatus of claim 6 wherein the PMIC comprises:
a multi-level charge pump (MCP) configured to generate the low-frequency voltage based on a battery voltage;
a power inductor configured to induce the low-frequency current based on the low-frequency voltage; and
a controller configured to adjust the low-frequency voltage and the low-frequency current based on a feedback signal.
8. The multi-mode power management apparatus of claim 7 wherein:
the first voltage circuit comprises:
a first voltage amplifier configured to generate a first initial ET voltage at a first coupling node based on the first ET target voltage;
a first offset capacitor having a first capacitance and coupled between the first coupling node and the first node, the first offset capacitor configured to raise the first initial ET voltage by a first offset voltage to generate the first ET voltage; and
a first switch coupled between the first coupling node and a ground;
the second voltage circuit comprises:
a second voltage amplifier configured to generate a second initial ET voltage at a second coupling node based on the second ET target voltage;
a second offset capacitor having a second capacitance smaller than the first capacitance and coupled between the second coupling node and the second node, the second offset capacitor configured to raise the second initial ET voltage by a second offset voltage to generate the second ET voltage; and
a second switch coupled between the second coupling node and the ground; and
the control circuit is coupled to the first voltage amplifier, the second voltage amplifier, the multifunction circuit, the first switch, the second switch, and the controller.
9. The multi-mode power management apparatus of claim 8 wherein the ETIC further comprises:
a supply voltage circuit configured to generate a multi-level supply voltage for one or more of the first voltage amplifier and the second voltage amplifier;
a first voltage equalizer circuit configured to generate the first ET target voltage based on a common ET target voltage; and
a second voltage equalizer circuit configured to generate the second ET target voltage based on the common ET target voltage.
10. The multi-mode power management apparatus of claim 8 wherein, in a first power management mode, the control circuit is further configured to:
activate the first voltage amplifier and the second voltage amplifier to cause the first node and the second node to output the first ET voltage and the second ET voltage, respectively;
control the multifunction circuit to generate an adjusted low-frequency current proportional to the low-frequency current; and
open the first switch and the second switch to cause the first node and the second node to output the low-frequency current and the adjusted low-frequency current, respectively.
11. The multi-mode power management apparatus of claim 10 wherein the control circuit is further configured to:
generate the feedback signal based on a voltage differential across the first offset capacitor; and
control the multifunction circuit based on a voltage differential across the second offset capacitor.
12. The multi-mode power management apparatus of claim 10 wherein the first ET target voltage is delayed from the second ET target voltage based on a determined temporal delay between the driver stage and the output stage of the multi-stage power amplifier circuit.
13. The multi-mode power management apparatus of claim 8 wherein, in a second power management mode, the control circuit is further configured to:
activate the first voltage amplifier and deactivate the second voltage amplifier to cause the first node and the second node to each output the first ET voltage;
control the multifunction circuit to couple the second node to the first node to receive the low-frequency current; and
open the first switch and the second switch to cause the first node and the second node to each output the low-frequency current.
14. The multi-mode power management apparatus of claim 13 wherein the control circuit is further configured to generate the feedback signal based on a voltage differential across the first offset capacitor.
15. The multi-mode power management apparatus of claim 8 wherein, in a second power management mode, the control circuit is further configured to:
deactivate the first voltage amplifier and activate the second voltage amplifier to cause the first node and the second node to each output the second ET voltage;
control the multifunction circuit to couple the second node to the first node to receive the low-frequency current; and
open the first switch and the second switch to cause the first node and the second node to each output the low-frequency current.
16. The multi-mode power management apparatus of claim 15 wherein the control circuit is further configured to generate the feedback signal based on a voltage differential across the first offset capacitor.
17. The multi-mode power management apparatus of claim 8 wherein, in a second power management mode, the control circuit is further configured to:
deactivate the first voltage amplifier and the second voltage amplifier;
control the multifunction circuit to couple the second node to the first node to receive the low-frequency current; and
close the first switch and open the second switch to cause the low-frequency voltage to be modulated across the first offset capacitor.
18. The multi-mode power management apparatus of claim 17 wherein the control circuit is further configured to generate the feedback signal based on a voltage differential across the first offset capacitor.
19. The multi-mode power management apparatus of claim 8 wherein, in a second power management mode, the control circuit is further configured to:
deactivate the first voltage amplifier and the second voltage amplifier;
control the multifunction circuit to couple the second node to the first node to receive the low-frequency current; and
open the first switch and close the second switch to cause the low-frequency voltage to be modulated across the second offset capacitor.
20. The multi-mode power management apparatus of claim 19 wherein the control circuit is further configured to generate the feedback signal based on a voltage differential across the first offset capacitor.