Fast-switching power management integrated circuit
A fast-switching power management integrated circuit (PMIC) is provided. The PMIC is configured to provide an average power tracking (APT) voltage to a power amplifier circuit for amplifying a radio frequency (RF) signal modulated in multiple time intervals. Herein, the PMIC is configured to increase or decrease the APT voltage from a present voltage level in a present one of the time intervals to a future voltage level in an upcoming one of the time intervals with very short switching interval (e.g., <20 nanoseconds). When the APT voltage transitions from the present voltage level to the future voltage level, the PMIC opportunistically activates a voltage amplifier to help ensure proper operation of the power amplifier circuit (e.g., maintain the APT voltage at the present level and reduce ripple in the APT voltage). As a result, the PMIC can switch the APT voltage frequently and rapidly with reduced inrush current.
1 . A power management integrated circuit (PMIC) comprising:
a voltage output that outputs an average power tracking (APT) voltage to a power amplifier circuit for amplifying a radio frequency (RF) signal modulated in a plurality of modulation units each comprising a plurality of time intervals;
an offset circuit coupled to the voltage output and configured to change the APT voltage from a present voltage level in a present time interval among the plurality of time intervals to a future voltage level in an upcoming time interval among the plurality of time intervals during a transition interval that falls within one of the present time interval and the upcoming time interval; and
a voltage amplifier coupled to an input of the offset circuit, the voltage amplifier is activated at a start of the transition interval and deactivated at an end of the transition interval to generate a modulated voltage at the input of the offset circuit based on an amplifier target voltage determined to cause the modulated voltage to be higher than or equal to a headroom voltage at the end of the transition interval.
2 . The PMIC of claim 1 , further comprising a control circuit configured to:
determine the start and the end of the transition interval based on the present voltage level and the future voltage level of the APT voltage;
determine the amplifier target voltage to be equal to a sum of the future voltage level and a markup voltage;
activate the voltage amplifier at the start of the transition interval; and
deactivate the voltage amplifier at the end of the transition interval.
3 . The PMIC of claim 2 , wherein the control circuit is further configured to:
determine that the future voltage level of the APT voltage is higher than the present voltage level of the APT voltage;
determine the start of the transition interval to be at a boundary between the present time interval and the upcoming time interval;
determine the end of the transition interval to be later than the boundary between the present time interval and the upcoming time interval;
determine the markup voltage to be equal to the headroom voltage; and
cause the offset circuit to increase the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
4 . The PMIC of claim 2 , wherein the control circuit is further configured to:
determine that the future voltage level of the APT voltage is lower than the present voltage level of the APT voltage and the headroom voltage is lower than a differential between the present voltage level and the future voltage level;
determine the start of the transition interval to be earlier than a boundary between the present time interval and the upcoming time interval;
determine the end of the transition interval to be at the boundary between the present time interval and the upcoming time interval;
determine the markup voltage to be equal to zero; and
cause the offset circuit to decrease the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
5 . The PMIC of claim 2 , wherein the control circuit is further configured to:
determine that the future voltage level of the APT voltage is lower than the present voltage level of the APT voltage and the headroom voltage is higher than or equal to a differential between the present voltage level and the future voltage level;
determine the start of the transition interval to be earlier than a boundary between the present time interval and the upcoming time interval;
determine the end of the transition interval to be at the boundary between the present time interval and the upcoming time interval;
determine the markup voltage to be equal to the headroom voltage subtracted by the differential between the present voltage level and the future voltage level; and
cause the offset circuit to decrease the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
6 . The PMIC of claim 2 , wherein the control circuit is further configured to receive, during the present time interval, an indication that indicates the future voltage level of the APT voltage in the upcoming time interval.
7 . The PMIC of claim 2 , wherein the control circuit is further configured to receive, during a present one of the plurality of modulation units, a profile indication that indicates a selected power profile for an upcoming one of the plurality of modulation units, the selected power profile comprises a plurality of future voltage levels each corresponding to a respective one of the plurality of time intervals in the upcoming one of the plurality of modulation units.
8 . The PMIC of claim 7 , further comprising a memory circuit configured to store a profile lookup table (LUT) comprising a plurality of predetermined power profiles, wherein the control circuit is further configured to retrieve the selected power profile from the profile LUT based on the received indication.
9 . The PMIC of claim 1 , wherein:
the plurality of modulation units each corresponds to a time division duplex, TDD, time slot; and
the plurality of time intervals in each of the plurality of modulation units corresponds to an orthogonal frequency division multiplexing, OFDM, symbol.
10 . A wireless communication circuit comprising a power management integrated circuit (PMIC) comprising:
a voltage output that outputs an average power tracking (APT) voltage for amplifying a radio frequency, RF, signal modulated in a plurality of modulation units each comprising a plurality of time intervals;
an offset circuit coupled to the voltage output and configured to change the APT voltage from a present voltage level in a present time interval among the plurality of time intervals to a future voltage level in an upcoming time interval among the plurality of time intervals during a transition interval that falls within one of the present time interval and the upcoming time interval; and
a voltage amplifier coupled to an input of the offset circuit, the voltage amplifier is activated at a start of the transition interval and deactivated at an end of the transition interval to generate a modulated voltage at the input of the offset circuit based on an amplifier target voltage determined to cause the modulated voltage to be higher than or equal to a headroom voltage at the end of the transition interval.
11 . The wireless communication circuit of claim 10 , wherein the PMIC further comprises a control circuit configured to:
determine the start and the end of the transition interval based on the present voltage level and the future voltage level of the APT voltage;
determine the amplifier target voltage to be equal to a sum of the future voltage level and a markup voltage;
activate the voltage amplifier at the start of the transition interval; and
deactivate the voltage amplifier at the end of the transition interval.
12 . The wireless communication circuit of claim 11 , wherein the control circuit is further configured to:
determine that the future voltage level of the APT voltage is higher than the present voltage level of the APT voltage;
determine the start of the transition interval to be at a boundary between the present time interval and the upcoming time interval;
determine the end of the transition interval to be later than the boundary between the present time interval and the upcoming time interval;
determine the markup voltage to be equal to the headroom voltage; and
cause the offset circuit to increase the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
13 . The wireless communication circuit of claim 11 , wherein the control circuit is further configured to:
determine that the future voltage level of the APT voltage is lower than the present voltage level of the APT voltage and the headroom voltage is lower than a differential between the present voltage level and the future voltage level;
determine the start of the transition interval to be earlier than a boundary between the present time interval and the upcoming time interval;
determine the end of the transition interval to be at the boundary between the present time interval and the upcoming time interval;
determine the markup voltage to be equal to zero; and
cause the offset circuit to decrease the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
14 . The wireless communication circuit of claim 11 , wherein the control circuit is further configured to:
determine that the future voltage level of the APT voltage is lower than the present voltage level of the APT voltage and the headroom voltage is higher than or equal to a differential between the present voltage level and the future voltage level;
determine the start of the transition interval to be earlier than a boundary between the present time interval and the upcoming time interval;
determine the end of the transition interval to be at the boundary between the present time interval and the upcoming time interval;
determine the markup voltage to be equal to the headroom voltage subtracted by the differential between the present voltage level and the future voltage level; and
cause the offset circuit to decrease the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
15 . The wireless communication circuit of claim 11 , wherein the control circuit is further configured to receive, during the present time interval, an indication that indicates the future voltage level of the APT voltage in the upcoming time interval.
16 . The wireless communication circuit of claim 11 , wherein the control circuit is further configured to receive, during a present one of the plurality of modulation units, a profile indication that indicates a selected power profile for an upcoming one of the plurality of modulation units, the selected power profile comprises a plurality of future voltage levels each corresponding to a respective one of the plurality of time intervals in the upcoming one of the plurality of modulation units.
17 . The wireless communication circuit of claim 16 , wherein the PMIC further comprises a memory circuit configured to store a profile lookup table, LUT, comprising a plurality of predetermined power profiles, wherein the control circuit is further configured to retrieve the selected power profile from the profile LUT based on the received indication.
18 . The wireless communication circuit of claim 10 , wherein:
the plurality of modulation units each corresponds to a time division duplex (TDD) time slot; and
the plurality of time intervals in each of the plurality of modulation units corresponds to an orthogonal frequency division multiplexing (OFDM) symbol.
19 . The wireless communication circuit of claim 10 , further comprising a transceiver circuit configured to:
generate the RF signal and modulate the RF signal in the plurality of modulation units each comprising the plurality of time intervals; and
provide a modulated target voltage to the PMIC to indicate the future voltage level in the upcoming time interval among the plurality of time intervals.
20 . The wireless communication circuit of claim 10 , further comprising a power amplifier circuit configured to amplify the RF signal in each of the plurality of time intervals based on the APT voltage.
21 . A method for fast switching an average power tracking (APT) voltage in a power management integrated circuit (PMIC) comprising:
outputting the APT voltage for amplifying a radio frequency (RF) signal modulated in a plurality of modulation units each comprising a plurality of time intervals;
changing the APT voltage from a present voltage level in a present time interval among the plurality of time intervals to a future voltage level in an upcoming time interval among the plurality of time intervals during a transition interval that falls within one of the present time interval and the upcoming time interval; and
activating a voltage amplifier at a start of the transition interval and deactivating the voltage amplifier at an end of the transition interval to generate a modulated voltage based on an amplifier target voltage determined to cause the modulated voltage to be higher than or equal to a headroom voltage at the end of the transition interval.
22 . The method of claim 21 , further comprising:
determining the start and the end of the transition interval based on the present voltage level and the future voltage level of the APT voltage;
determining the amplifier target voltage to be equal to a sum of the future voltage level and a markup voltage;
activating the voltage amplifier at the start of the transition interval; and
deactivating the voltage amplifier at the end of the transition interval.
23 . The method of claim 22 , further comprising:
determining that the future voltage level of the APT voltage is higher than the present voltage level of the APT voltage;
determining the start of the transition interval to be at a boundary between the present time interval and the upcoming time interval;
determining the end of the transition interval to be later than the boundary between the present time interval and the upcoming time interval;
determining the markup voltage to be equal to the headroom voltage; and
increasing the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
24 . The method of claim 22 , further comprising:
determining that the future voltage level of the APT voltage is lower than the present voltage level of the APT voltage and the headroom voltage is lower than a differential between the present voltage level and the future voltage level;
determining the start of the transition interval to be earlier than a boundary between the present time interval and the upcoming time interval;
determining the end of the transition interval to be at the boundary between the present time interval and the upcoming time interval;
determining the markup voltage to be equal to zero; and
decreasing the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
25 . The method of claim 22 , further comprising:
determining that the future voltage level of the APT voltage is lower than the present voltage level of the APT voltage and the headroom voltage is higher than or equal to a differential between the present voltage level and the future voltage level;
determining the start of the transition interval to be earlier than a boundary between the present time interval and the upcoming time interval;
determining the end of the transition interval to be at the boundary between the present time interval and the upcoming time interval;
determining the markup voltage to be equal to the headroom voltage subtracted by the differential between the present voltage level and the future voltage level; and
decreasing the APT voltage from the present voltage level to the future voltage level by the end of the transition interval.
26 . The method of claim 22 , further comprising receiving, during the present time interval, an indication that indicates the future voltage level of the APT voltage in the upcoming time interval.
27 . The method of claim 22 , further comprising receiving, during a present one of the plurality of modulation units, a profile indication that indicates a selected power profile for an upcoming one of the plurality of modulation units, the selected power profile comprises a plurality of future voltage levels each corresponding to a respective one of the plurality of time intervals in the upcoming one of the plurality of modulation units.
28 . The method of claim 27 , further comprising:
storing a profile lookup table (LUT) comprising a plurality of predetermined power profiles; and
retrieving the selected power profile from the profile LUT based on the received indication.
29 . The method of claim 21 , wherein:
the plurality of modulation units each corresponds to a time division duplex (TDD) time slot; and
the plurality of time intervals in each of the plurality of modulation units corresponds to an orthogonal frequency division multiplexing (OFDM) symbol.