Circuits and methods related to switchless carrier aggregation in radio-frequency receivers

1. A carrier aggregation (CA) circuit comprising

an input node, a common node, and an output node;

a first filter configured to allow operation in a first frequency band;

a second filter configured to allow operation in a second frequency band;

a first amplification path implemented between the input node and the output node, and including the first filter, a first current converter stage implemented as a bipolar junction transistor configured to receive a signal through its base and generate an output through its collector, the common node, and a common adder stage implemented as a shared bipolar junction transistor, the first amplification path free of switches; and

a second amplification path implemented between the input node and the output node, and including the second filter, a second current converter stage implemented as a bipolar junction transistor configured to receive a signal through its base and generate an output through its collector, the common node, and the common adder stage, the second amplification path free of switches, the shared bipolar junction transistor configured to receive the signals output from the bipolar junction transistors of the first and second current converter stages through its emitter and generate an output through its collector, the first and second current converter stages and the common adder stage being parts of a low-noise amplifier.

2. The carrier aggregation circuit of claim 1 wherein the first amplification path and the second amplification path being free of switches allows the carrier aggregation circuit to operate with a reduced noise figure.

3. The carrier aggregation circuit of claim 1 further comprising a bias circuit coupled to the bipolar junction transistors of the first and second current converter stages, and including a switchable bias supply path between a respective bias node and the respective base, the switchable bias supply path configured to be capable of being turned on or off to activate or deactivate the respective bipolar junction transistor.

4. The carrier aggregation circuit of claim 3 wherein the bias circuit further includes a switchable shunt path configured to provide a shunt path when the respective bipolar junction transistor is deactivated.

5. The carrier aggregation circuit of claim 1 wherein the bipolar junction transistor of each of the first and second current converter stages includes an emitter coupled to ground through an inductance.

6. The carrier aggregation circuit of claim 1 wherein the shared bipolar junction transistor is configured to receive a cascode bias voltage through its base.

7. The carrier aggregation circuit of claim 1 wherein each of the first amplification path and the second amplification path is capable of being in an active state or an inactive state to allow the carrier aggregation circuit to operate in a carrier aggregation mode or a non-carrier aggregation mode without separate switches along the first amplification path and the second amplification path.

8. The carrier aggregation circuit of claim 7 wherein the active state or the inactive state for each of the first amplification path and the second amplification path is achieved by activating or deactivating the respective current converter stage.

9. A radio-frequency module comprising:

a packaging substrate configured to receive a plurality of components; and

a carrier aggregation circuit implemented on the packaging substrate, and including an input node, a common node, and an output node, the carrier aggregation circuit further including a first filter configured to allow operation in a first frequency band and a second filter configured to allow operation in a second frequency band, the carrier aggregation circuit further including a first amplification path implemented between the input node and the output node, and including the first filter, a first current converter stage implemented as a bipolar junction transistor configured to receive a signal through its base and generate an output through its collector, the common node, and a common adder stage implemented as a shared bipolar junction transistor, the first amplification path free of switches, the carrier aggregation circuit further including a second amplification path implemented between the input node and the output node, and including the second filter, a second current converter stage implemented as a bipolar junction transistor configured to receive a signal through its base and generate an output through its collector, the common node, and the common adder stage, the second amplification path free of switches, the shared bipolar junction transistor configured to receive the signals output from the bipolar junction transistors of the first and second current converter stages through its emitter and generate an output through its collector, the first and second current converter stages and the common adder stage being parts of a low-noise amplifier.

10. The radio-frequency module of claim 9 wherein each of the first filter and the second filter includes a surface acoustic wave filter.

11. The radio-frequency module of claim 10 wherein the radio-frequency module is a diversity receive module.

12. A wireless device comprising:

a receiver configured to process radio-frequency signals;

module in communication with the receiver, and including a carrier aggregation circuit configured to route the radio-frequency signals, the carrier aggregation circuit including an input node, a common node, and an output node; a first filter configured to allow operation in a first frequency band and a second filter configured to allow operation in a second frequency band; a first amplification path implemented between the input node and the output node, and including the first filter, a first current converter stage implemented as a bipolar junction transistor configured to receive a signal through its base and generate an output through its collector, the common node, and a common adder stage implemented as a shared bipolar junction transistor, the first amplification path free of switches; and a second amplification path implemented between the input node and the output node, and including the second filter, a second current converter stage implemented as a bipolar junction transistor configured to receive a signal through its base and generate an output through its collector, the common node, and the common adder stage, the second amplification path free of switches, the shared bipolar junction transistor configured to receive the signals output from the bipolar junction transistors of the first and second current converter stages through its emitter and generate an output through its collector, the first and second current converter stages and the common adder stage being parts of a low-noise amplifier; and

an antenna in communication with the radio-frequency module, and configured to receive the radio-frequency signals.

13. The wireless device of claim 12 wherein the antenna includes a diversity antenna, and the module includes a diversity receive module.

14. The wireless device of claim 13 further comprising an antenna switch module configured to route the radio-frequency signals from the diversity antenna to the receiver, such that the diversity receive module is implemented between the diversity antenna and the antenna switch module.