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 mobile terminal comprising:
a system adapted to:
i) measure a battery voltage of a battery of the mobile terminal at a no-load condition to provide a no-load battery voltage;
ii) measure the battery voltage of the battery at a full-load condition during a first transmit burst to provide a full-load battery voltage;
iii) measure 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;
iv) determine a battery resistance based on the no-load battery voltage, the full-load battery voltage, and the full-load current; and
v) provide the battery resistance as an indicator of remaining battery-life for the battery of the mobile terminal, wherein the system is further adapted to measure the battery voltage prior to ramp-up for the first transmit burst to measure the battery voltage at a no-load condition.
2. The mobile terminal of claim 1 wherein the battery resistance is compared to at least one resistance threshold to provide an indication of remaining battery-life for the battery of the mobile terminal.
3. The mobile terminal of claim 1 wherein the battery resistance is compared 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, the series of resistance thresholds corresponding to a series of remaining battery-life levels.
4. The mobile terminal of claim 1 wherein the system is further adapted to determine 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. The mobile terminal of claim 1 wherein the system is further adapted to measure the battery voltage after ramp-up for the first transmit burst to measure the battery voltage at a full-load condition.
6. The mobile terminal of claim 1 wherein the mobile terminal operates according to a modulation scheme having an amplitude modulation component, and the system is further adapted to measure the battery voltage during a constant envelope period occurring immediately prior to ramp-down for the first transmit burst in order to measure the battery voltage at a full-load condition.
7. The mobile terminal of claim 1 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 the system is further adapted to measure 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 in order to measure the battery voltage at a full-load condition.
8. The mobile terminal 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.