Power dissipation reduction in wireless transceivers
Processes, methods and circuits for improving battery life by reducing the battery power-drain of battery-powered devices with wireless receivers is disclosed. Embodiments provide for variably changing the bias current, impedance, and gain through a plurality of values, either separately or in combination, during receiver circuit operation to optimize power dissipation. The dynamic changes to gain, bias and impedance characteristics of the receiver circuit may occur in any of an amplifier, a filter, and a mixer, and are responsive to the components of an input signal comprising a desired signal and interferer signal. Dynamic changes may also be made to a dynamic range and noise floor of the receiver circuit.
1. A method for power dissipation reduction in a receiver of a wireless transceiver of a battery powered portable wireless device, and a corresponding improvement 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 at a first node in the receiver signal path; and
varying an impedance and a bias current of 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;
wherein the bias current and the impedance of the circuit in the receiver signal path of the wireless transceiver are varied 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, the bias current of the circuit in the receiver signal path of the wireless transceiver is increased and the impedance of the circuit in the receiver signal path of the wireless transceiver is reduced, resulting in a first current drain;
(ii) when the signal strength of the interferer signal is high and the signal strength of the desired signal is high, the bias current of the circuit in the receiver signal path of the wireless transceiver is increased while the impedance of the circuit in the receiver signal path of the wireless transceiver is increased, resulting in a reduction in current drain when compared to the first current drain;
(iii) when the signal strength of the interferer signal is low and the signal strength of the desired signal is low, the bias current of the circuit in the receiver signal path of the wireless transceiver is reduced and the impedance of the circuit in the receiver signal path of the wireless transceiver is reduced resulting in reduced current drain when compared to the first current drain; and
(iv) when the signal strength of the interferer signal is low and the signal strength of the desired signal is high, the bias current of the circuit in the receiver signal path of the wireless transceiver is increased and the impedance of the circuit in the receiver signal path of the wireless transceiver is increased, resulting in a reduction in current drain compared to the first current drain.
2. The method of claim 1 , wherein the circuit in the receiver signal path of the wireless transceiver whose impedance is varied is the amplifier.
3. The method of claim 1 , wherein the circuit in the receiver signal path of the wireless transceiver whose impedance is varied is the mixer.
4. The method of claim 1 , wherein the circuit in the receiver signal path of the receiver transceiver whose impedance is varied is the filter.
5. The method of claim 1 , wherein varying the impedance of the circuit in the receiver signal path of the wireless transceiver is affected by switching in and out an impedance in series with a load of the circuit in the receiver signal path of the wireless transceiver.
6. The method of claim 1 , wherein varying the bias current of the circuit in the receiver signal path of the wireless transceiver is affected by varying an impedance in a bias current path of the circuit in the receiver signal path of the wireless transceiver.