Dual Mode Radio Frequency Front End Circuit

A dual mode radio frequency (RF) front end circuit, comprising:

• first and second transformers for conversion between balanced and unbalanced RF signals;
• a first switch configured to selectively electrically connect to one of the first and second transformers and an RF transmit port;
• a filter coupled to the first switch, the filter being selectively electrically connected to one of the first and second transformers and the RF transmit port by operation of the first switch;
• a second switch configured to selectively electrically connect the filter to one of the input and output ports of an amplifier and to selectively electrically connect an antenna port to one of the input and the output ports of the amplifier, the filter being electrically connected to the input port of the amplifier when the antenna port is electrically connected to the output port of the amplifier and the filter being electrically connected to the output port of the amplifier when the antenna port is connected to the input port of the amplifier.

A radio frequency (RF) communication system comprising:

• a first transceiver circuit operating in a selected frequency band;
• a second transceiver circuit operating in the selected frequency band;
• a front end circuit coupled to the first and second transceiver circuits, the front end circuit comprising:
• first and second transformers for conversion between balanced and unbalanced RF signals;
• a first switch configured to selectively electrically connect to one of the first and second transformers and an RF transmit port;
• and
• a second switch configured to selectively electrically connect the first switch to one of the input and output ports of an amplifier and to selectively electrically connect a filter to one of the input and the output ports of the amplifier to a filter, the first switch being electrically connected to the input port of the amplifier when the filter is electrically connected to the output port of the amplifier and the first switch being electrically connected to the output port of the amplifier when the filter is connected to the input port of the amplifier;
• and
• an antenna coupled to the filter.

A radio frequency (RF) communication system comprising:

• a Bluetooth transceiver circuit operating in a selected frequency band;
• a WLAN transceiver circuit operating in the selected frequency band;
• a front end circuit coupled to the Bluetooth and WLAN transceiver circuits, the front end circuit comprising:
• first and second transformers for conversion between balanced and unbalanced RF signals;
• a single pole triple throw (SP3T) switch configured to selectively electrically connect to one of the first and second transformers and an RF transmit port;
• and
• a double port double throw (DPDT) switch configured to selectively electrically connect the SP3T switch to one of the input and output Ports of an amplifier and to selectively electrically connect a filter to one of the input and the output ports of the amplifier to a filter, the SP3T switch being electrically connected to the input port of the amplifier when the filter is electrically connected to the output port of the amplifier and the SP3T switch being electrically connected to the output port of the amplifier when the filter is connected to the input port of the amplifier;
• and
• an antenna coupled to the filter.

A radio frequency (RF) front end circuit, comprising:

• first and second transformers for conversion between balanced and unbalanced RF signals;
• a first switch configured to selectively electrically connect to one of the first and second transformers and an RF transmit port;
• and
• a second switch configured to selectively electrically connect the first switch to one of the input and output ports of an amplifier and to selectively electrically connect a filter to one of the input and the output ports of the amplifier to the filter, the first switch being electrically connected to the input port of the amplifier when the filter is electrically connected to the output port of the amplifier and the first switch being electrically connected to the output port of the amplifier when the filter is connected to the input port of the amplifier,
• wherein the amplifier operates as a power amplifier when its input port is electrically connected to the first switch due to selective operation of the second switch, and the amplifier operates as a low noise amplifier when its output port is electrically connected to the first switch due to selective operation of the second switch.