RC Network Input Matching for DSDS Auxiliary LNA Power Saving
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Solution Overview
Problem
In dual SIM dual standby (DSDS) operation, existing RF transceivers consume unnecessary power as the main low noise amplifier (LNA) remains active even when there is no main receive signal, due to the need for input matching with an auxiliary high impedance amplifier, which reduces battery life.
Innovation Solution
A resistive-capacitive (RC) network is used to selectively modify the input impedance of the amplifier, allowing the auxiliary LNA to operate independently of the main LNA, enabling input impedance matching without activating the main LNA when not needed, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main LNA is kept active to maintain input matching for the auxiliary high impedance amplifier, then input impedance matching is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the input impedance of the auxiliary amplifier adjustable rather than fixed. A resistive-capacitive (RC) network is introduced that can dynamically modify the input impedance based on operating conditions. The network includes a resistor and capacitor connected in parallel, with the capacitor value selectable based on whether the main LNA is active or inactive, allowing the auxiliary amplifier to achieve proper input matching independently without requiring the main LNA to remain powered on.
Solution Approach 2:
The patent changes the electrical parameters of the auxiliary amplifier's input circuit by introducing an RC network. The capacitor value is changed depending on the operational state (main LNA active or inactive), which modifies the input impedance characteristics. This parameter change enables the auxiliary amplifier to maintain proper input matching while operating independently, resolving the contradiction between maintaining matching and reducing power consumption.
2Use of energy by moving object
If the auxiliary LNA operates independently without the main LNA, then power consumption is reduced, but input impedance matching deteriorates
Solution Approach 1:
The RC network serves as an intermediary between the auxiliary amplifier and the signal source. The resistor and capacitor in parallel act as an impedance transformation network that mediates the high output impedance of the auxiliary amplifier to achieve proper 50-ohm input matching. This intermediary network enables the auxiliary amplifier to operate independently with proper matching, eliminating the need to keep the main LNA active.
3Reliability
If the main LNA is activated for DSDS paging signal reception, then signal detection capability is improved, but battery life is reduced
Solution Approach 1:
The patent extracts the input impedance matching function from the main LNA and assigns it to a dedicated RC network associated with the auxiliary amplifier. This extraction allows the auxiliary amplifier to perform paging signal detection independently without relying on the main LNA being active. The main LNA can be completely powered down during DSDS paging reception, eliminating its power consumption while maintaining signal detection capability through the auxiliary amplifier with the RC network.
Data Source
AI summary
An apparatus includes a first amplifier stage configured to amplify a first carrier signal. The apparatus includes a second amplifier stage configured to amplify a second carrier signal. A resistive-capacitive (RC) network is coupled to the first amplifier stage and to the second amplifier stage. The RC network includes a resistive element coupled to a capacitive element.