US 2017/0250728 A1Published application

Integrated transmit/receive switch with power amplifier transformer reuse

AssigneeBroadcom Corporation

InventorsAli AFSAHI, Hongrui WANG

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Abstract

A transmit/receive switch architecture is provided which reuses a power amplifier's transformer as part of the low noise amplifier (LNA) input matching network. A front-end circuit includes a transmit/receive switch. The transmit/receive switch includes a transformer that includes primary winding and secondary winding. The transmit/receive also includes a transistor, where a drain of the transistor is connected to the secondary winding and a gate of the transistor is configured to receive a control signal. The transmit/receive switch operates as a receive switch when the control signal is low and inputs of the primary winding are either shorted or at open circuit. The transmit/receive switch operates as a transmit switch when the control signal is high.

Claims21

Dependent claims

A front-end circuit of a communication device, the front-end circuit comprising:

a power amplifier;
a low noise amplifier;
and
a transmit/receive switch configured to provide an output signal from the power amplifier to an antenna during a transmit mode, and provide an input signal from the antenna to the low noise amplifier during a receive mode, the transmit/receive switch comprising:
a transformer including a primary winding and a secondary winding, wherein the primary winding is directly connected to a differential output of the power amplifier, and wherein the secondary winding has a first terminal connected to the antenna and a second terminal coupled to an input of the low noise amplifier;
and
a switch having a first terminal connected to the second terminal of the secondary winding and a second terminal connected to ground;
and
a multiplexer, comprising:
a differential input to receive a differential input signal for transmit by the antenna during the transmit mode;
a second input connected to a direct current (DC) voltage;
and
an output connected to a differential input of the power amplifier.

10 more elements

A front-end circuit of a communication device, the front-end circuit comprising:

a transmit/receive switch configured to provide an output signal from a power amplifier to an antenna during a transmit mode, and provide an input signal from the antenna to a low noise amplifier during a receive mode, the transmit/receive switch comprising:
a transformer including a primary winding and a secondary winding, wherein the primary winding is directly connected to a differential output of the power amplifier, and wherein the secondary winding has a first terminal connected to the antenna and a second terminal coupled to the input of the low noise amplifier;
and
a switch having a first terminal connected to the second terminal of the secondary winding and a second terminal connected to ground;
and
a multiplexer configured to select between a differential input signal received at a first input and a direct current (DC) voltage received at a second input, to provide a selected signal to an input of the power amplifier,
wherein, during the transmit mode, the multiplexer is configured to select the differential input signal at the first input as the selected signal provided to the input of the power amplifier, and
wherein, during the receive mode, the multiplexer is configured to select the DC voltage at the second input as the selected signal provided to the input of the power amplifier.

5 more elements

Dependencies are inferred from the claim text.