Utilizing computed battery resistance as a battery-life indicator in a mobile terminal
View Patent ↗An over-voltage detection and correction system for a transmitter of a mobile terminal that accounts for battery droop during a transmit burst is provided. In general, prior to ramp-up for a first transmit burst, a voltage of the battery of the mobile terminal at a no-load condition is measured. After ramp-up for the transmit burst, the voltage of the battery is measured at full-load, and a current provided to a power amplifier of the transmitter at full-load is detected. Based on the measured voltage of the battery at no-load, the measured voltage of the battery at full-load, and the detected current provided to the power amplifier at full-load, a resistance of the battery is determined. The battery resistance is thereafter updated as desired and used as an indicator of remaining battery-life or power of the battery of the mobile terminal.
1. A method comprising:
measuring a battery voltage of a battery of a mobile terminal at a no-load condition prior to ramp-up for a first transmit burst to provide a no-load battery voltage;
measuring the battery voltage of the battery at a full-load condition during the first transmit burst to provide a full-load battery voltage;
measuring a current provided from the battery to power amplifier circuitry in a transmit chain of the mobile terminal at a full-load condition during the first transmit burst to provide a full-load current;
determining a battery resistance based on the no-load battery voltage, the full-load battery voltage, and the full-load current; and
providing the battery resistance as an indicator of remaining battery-life for the battery of the mobile terminal.
2. The method of claim 1 further comprising comparing the battery resistance to at least one resistance threshold to provide an indication of remaining battery-life for the battery of the mobile terminal.
3. The method of claim 1 further comprising comparing the battery resistance to at least one of a series of resistance thresholds to provide an indication of remaining battery-life for the battery of the mobile terminal, wherein the series of resistance thresholds corresponds to a series of remaining battery-life levels.
4. The method of claim 1 wherein determining the battery resistance comprises determining the battery resistance based on the equation:
R
B
=
V
BAT_NO
_LOAD
-
V
BAT_FULL
_LOAD
I
FULL_LOAD
,
wherein R B is the battery resistance, V BAT — NO — LOAD is the no-load battery voltage, V BAT — FULL — LOAD is the full-load battery voltage, and I FULL — LOAD is the full-load current.
5. A method comprising:
measuring a battery voltage of a battery of a mobile terminal at a no-load condition to provide a no-load battery voltage, wherein measuring the battery voltage at a no-load condition comprises measuring the battery voltage prior to ramp-up for the first transmit burst;
measuring the battery voltage of the battery at a full-load condition after ramp-up for a first transmit burst and during the first transmit burst to provide a full-load battery voltage;
measuring a current provided from the battery to power amplifier circuitry in a transmit chain of the mobile terminal at the full-load condition during the first transmit burst to provide a full-load current;
determining a battery resistance based on the no-load battery voltage, the full-load battery voltage, and the full-load current; and providing the battery resistance as an indicator of remaining battery-life for the battery of the mobile terminal.
6. The method of claim 5 wherein the mobile terminal operates according to a modulation scheme having an amplitude modulation component, and measuring the battery voltage at a full-load condition comprises measuring the battery voltage during a constant envelope period occurring immediately prior to ramp-down for the first transmit burst.
7. The method of claim 5 wherein the mobile terminal operates according to an 8-Level Phase Shift Keying (8PSK) modulation scheme of the Enhanced Data Rates for GSM Evolution (EDGE) standard, and measuring the battery voltage at a full-load condition comprises measuring the battery voltage during a constant envelope period beginning at 2.5 symbol periods after a center of a last data symbol of the first transmit burst and ending at a start of ramp-down for the first transmit burst.
8. The method of claim 1 further comprising:
measuring the battery voltage of the battery of the mobile terminal at a no-load condition prior to ramp-up for a subsequent transmit burst to provide a no-load battery voltage for the subsequent transmit burst;
measuring the battery voltage of the battery at a full-load condition during the subsequent transmit burst to provide a full-load battery voltage for the subsequent transmit burst;
measuring a current provided from the battery to the power amplifier circuitry in the transmit chain of the mobile terminal at a full-load condition during the subsequent transmit burst to provide a full-load current for the subsequent transmit burst;
updating the battery resistance based on the no-load battery voltage, the full-load battery voltage, and the full-load current for the subsequent transmit burst; and
providing the updated battery resistance as the indicator of remaining battery-life for the battery of the mobile terminal.
9. The method of claim 8 wherein updating the battery resistance comprises updating the battery resistance if a difference between the no-load battery voltage and the full-load battery voltage for the subsequent transmit burst exceeds a predetermined threshold.
10. The method of claim 1 wherein the battery resistance is a resistance of the battery plus a resistance of any elements connected between the battery and the power amplifier circuitry.