Power dissipation reduction in wireless transceivers
Processes, methods and circuits for improving battery life by reducing the battery power-drain of battery-powered devices using wireless transceivers is disclosed. Embodiments of the present invention provide for dynamically changing the bias current, impedance, and gain, either separately or in combination, during circuit operation to optimize or to reduce power dissipation. The dynamic variations may be implemented by varying the value of a resistance and/or a capacitance by opening switches across one or more portions of the resistance. Also, the dynamic variations may include setting any of the gain, bias current, or impedance parameters of the receiver circuit in between a high and low level, followed by adjusting the parameter up or down in response to a desired signal and an interferer signal.
1. A method for power dissipation reduction in a receiver of a wireless transceiver of a battery powered portable wireless device, and a corresponding increase in battery life of the battery powered portable wireless device, the method comprising:
receiving a wireless signal having a desired signal and an interferer signal, by the wireless transceiver of the battery powered portable wireless device, the wireless transceiver having a receiver signal path comprising a plurality of circuits, wherein the plurality of circuits includes an amplifier, a filter, and a mixer, and wherein the wireless transceiver comprises a circuit for determining a signal strength of the interferer signal and a circuit for determining a signal strength of the desired signal;
wherein a worst-case power dissipation condition results when the signal strength of the desired signal is low and the signal strength of the interferer signal is high; and
wherein the power dissipation reduction in the receiver is achieved by causing a bias current to vary in one or more of the plurality of circuits in the receiver signal path of the wireless transceiver as the signal strength of the interferer signal and the signal strength of the desired signal vary according to the following:
(i) when the signal strength of the interferer signal is high and the signal strength of the desired signal is low, and the desired signal is larger than in the worst-case power dissipation condition, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be reduced compared to the worst-case power dissipation condition, thereby saving power; and
(ii) when the signal strength of the interferer signal is weak and the signal strength of the desired signal is weak, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be decreased compared to the worst-case power dissipation condition, thereby saving power.
2. The method of claim 1 , wherein the change in the bias current of the one or more of the plurality of circuits in the receiver signal path is related to a change in an impedance in the one or more of the plurality of circuits in the receiver signal path and wherein the impedance comprises at least a resistor and a capacitor.
3. A method for power dissipation reduction in a receiver of a wireless transceiver of a battery powered portable wireless device, and a corresponding increase in battery life of the battery powered portable wireless device, the method comprising:
receiving a wireless signal having a desired signal and an interferer signal, by the wireless transceiver of the battery powered portable wireless device, the wireless transceiver having a receiver signal path comprising a plurality of circuits, wherein the plurality of circuits includes an amplifier, a filter, and a mixer, and wherein the wireless transceiver comprises a circuit for determining a signal strength of the interferer signal and a circuit for determining a signal strength of the desired signal;
wherein a worst-case power dissipation condition from the battery results when the signal strength of the desired signal is low and the signal strength of the interferer signal is high; and
wherein the power dissipation reduction in the receiver is achieved by causing a bias current to vary in one or more of the plurality of circuits in the receiver signal path of the wireless transceiver as the signal strength of the interferer signal and the signal strength of the desired signal vary, according to the following:
when the signal strength of the interferer signal is high and the signal strength of the desired signal is low, and the desired signal has a signal strength that is larger than in the worst-case power dissipation conditions, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be decreased compared to the worst-case power dissipation condition, causing a reduction in power dissipation.
4. The method of claim 3 , wherein the change in the bias current of the one or more of the plurality of circuits in the receiver signal path is related to a change in an impedance in the one or more of the plurality of circuits in the receiver signal path;
and wherein the impedance comprises at least a resistor and a capacitor.
5. A method for power dissipation reduction in a receiver of a wireless transceiver of a battery powered portable wireless device, and a corresponding reduction in a drain on battery life of the battery powered portable wireless device, the method comprising:
receiving a wireless signal having a desired signal and an interferer signal, by the wireless transceiver of the battery powered portable wireless device, the wireless transceiver having a receiver signal path comprising a plurality of circuits, wherein the plurality of circuits includes an amplifier, a filter, and a mixer, and wherein the wireless transceiver comprises a circuit for determining a signal strength of the interferer signal and a circuit for determining a signal strength of the desired signal;
wherein a worst-case power dissipation condition results when the signal strength of the desired signal is low and the signal strength of the interferer signal is high; and
wherein the power dissipation reduction in the receiver is achieved by causing a bias current to vary in one or more of the plurality of circuits in the receiver signal path of the wireless transceiver as the signal strength of the interferer signal and the signal strength of the desired signal vary, according to the following:
(i) when the signal strength of the interferer signal is high and the signal strength of the desired signal is weak, and the desired signal is larger than in the worst-case power dissipation condition, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be reduced compared to the worst-case power dissipation condition, thereby saving power;
(ii) when the signal strength of the interferer signal is high and the signal strength of the desired signal is high, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be decreased compared to the worst-case power dissipation condition, thereby saving power;
(iii) when the signal strength of the interferer signal is weak and the signal strength of the desired signal is weak, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be decreased compared to the worst-case power dissipation condition, thereby saving power; and
(iv) when the signal strength of the interferer signal is weak and the signal strength of the desired signal is high, causing the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be decreased compared to the worst-case power dissipation condition, thereby saving power.
6. The method of claim 5 , wherein the change in the bias current of the one or more of the plurality of circuits in the receiver signal path is related to a change in an impedance in the one or more of the plurality of circuits in the receiver signal path;
and wherein the impedance comprises at least a resistor and a capacitor.
7. A method for power dissipation reduction in a receiver of a wireless transceiver of a battery powered portable wireless device, and a corresponding reduction in a drain on battery life of the battery powered portable wireless device, the method comprising:
receiving a wireless signal having a desired signal and an interferer signal, by the wireless transceiver of the battery powered portable wireless device, the wireless transceiver having a receiver signal path comprising a plurality of circuits, wherein the plurality of circuits includes an amplifier, a filter, and a mixer, and wherein the wireless transceiver comprises a circuit for determining a signal strength of the interferer signal and a signal strength of the desired signal in the receiver signal path;
wherein a worst-case power dissipation condition in the receiver results when the signal strength of the desired signal is low and the signal strength of the interferer signal is high; and
wherein the power dissipation reduction is achieved by causing an impedance and a bias current of one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to vary as the signal strength of the interferer signal and the signal strength of the desired signal to vary according to the following:
(i) when the signal strength of the interferer signal is high and the signal strength of the desired signal is low and the desired signal is larger than in the worst-case power dissipation conditions, causing the bias current of the circuit in the receiver signal path of the wireless transceiver to be reduced compared to the worst-case power dissipation condition, causing a reduction in power dissipation;
(ii) when the signal strength of the interferer signal is high and the signal strength of the desired signal is high, causing the impedance of the circuit in the receiver signal path of the wireless transceiver to be increased compared to the worst-case power dissipation condition, causing a reduction in power dissipation;
(iii) when the signal strength of the interferer signal is low and the signal strength of the desired signal is low, causing the bias current of the circuit in the receiver signal path of the wireless transceiver to be reduced compared to the worst-case power dissipation condition, causing a reduction in power dissipation;
(iv) when the signal strength of the interferer signal is low and the signal strength of the desired signal is high, causing the impedance of the circuit in the receiver signal path of the wireless transceiver to be increased compared to the worst-case power dissipation condition, causing a reduction in power dissipation; and
wherein increasing the impedance of the circuit reduces a drive current of the circuit and reduces the associated bias current of the circuit.
8. A method for power dissipation reduction in a receiver of a wireless transceiver of a battery powered portable wireless device, and a corresponding reduction in power dissipation and an increase in battery life of the battery powered portable wireless device, the method comprising:
receiving a wireless signal having a desired signal and an interferer signal, by the wireless transceiver of the battery powered portable wireless device, the wireless transceiver having a receiver signal path comprising a plurality of circuits, wherein the plurality of circuits includes an amplifier, a filter, and a mixer, and wherein the wireless transceiver comprises a circuit for determining a signal strength of the interferer signal and a circuit for determining a signal strength of the desired signal;
wherein a worst-case power dissipation condition from the battery results when the signal strength of the desired signal is low and the signal strength of the interferer signal is high; and
wherein the power dissipation reduction in the receiver is achieved by causing a bias current and an impedance to vary in one or more of the plurality of circuits in the receiver signal path of the wireless transceiver as the signal strength of the interferer signal and the signal strength of the desired signal vary, according to the following:
when the signal strength of the interferer signal is high and the signal strength of the desired signal is low, and the desired signal has a signal strength that is larger than in the worst-case power dissipation condition, causing:
(i) the bias current of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be decreased; and
(ii) an impedance of the one or more of the plurality of circuits in the receiver signal path of the wireless transceiver to be increased, thereby causing a drive current of the one or more of the plurality of circuits to be decreased.