INTEGRATED RADIO FREQUENCY TRANSMIT-RECEIVE SWITCH WITH EXTERNAL SWITCHING OPTION
The embodiments described herein are directed at techniques to perform T/R switching internally on a transceiver chip. An example transceiver chip includes a power amplifier coupled to an output terminal of the transceiver chip and a low noise amplifier coupled to an input terminal of the transceiver chip. The input terminal and the output terminal are separate terminals external to the transceiver chip. The transceiver chip also includes a shunt switch coupled in parallel with the low noise amplifier between the input terminal and ground and a control circuitry to activate the shunt switch to couple the input terminal to ground when the power amplifier is turned on.
1 . An apparatus comprising:
a transceiver chip comprising:
a power amplifier coupled to an output terminal of the transceiver chip;
a low noise amplifier coupled to an input terminal of the transceiver chip, wherein the input terminal and the output terminal are separate terminals external to the transceiver chip;
a shunt switch coupled in parallel with the low noise amplifier between the input terminal and ground; and
a control circuitry to activate the shunt switch to couple the input terminal to ground when the power amplifier is turned on; and
an antenna coupled to the transceiver chip and configured to:
provide a Radio Frequency (RF) input signal to the input terminal when the apparatus is in receive mode; and
receive an RF output signal from the output terminal when the apparatus is in transmit mode.
2 . The apparatus of claim 1 , comprising a bridge component external to the transceiver chip and configured to couple the input terminal with the output terminal.
3 . The apparatus of claim 2 , wherein the bridge component comprises a conductive trace.
4 . The apparatus of claim 2 , wherein the antenna is coupled to the input terminal directly and the antenna is coupled to the output terminal through the bridge component.
5 . The apparatus of claim 4 , comprising a gate inductor coupled to the input terminal and a shunt capacitor coupled to the input terminal in parallel with the antenna, wherein the gate inductor and the shunt capacitor form a parallel LC circuit configured to resonate at an operating frequency of the RF output signal when the apparatus is in transmit mode.
6 . The apparatus of claim 4 , wherein the bridge component comprises a capacitor or inductor configured to further impedance match the power amplifier to the antenna when the apparatus is in transmit mode.
7 . The apparatus of claim 2 , wherein the antenna is coupled to the output terminal directly and the antenna is coupled to the input terminal through the bridge component.
8 . The apparatus of claim 7 , comprising a gate inductor coupled to the input terminal and a shunt capacitor coupled to the output terminal in parallel with the antenna, wherein the shunt capacitor forms a parallel LC circuit in combination with the bridge component and the gate inductor, and wherein the parallel LC circuit is configured to resonate at an operating frequency of the RF output signal when the apparatus is in transmit mode.
9 . The apparatus of claim 8 , wherein the bridge component is a capacitor or inductor configured to further increase a real impedance of the parallel LC circuit when the apparatus is in transmit mode.
10 . The apparatus of claim 1 , further comprising:
a transmit/receive switch external to the transceiver chip and coupled between the input terminal, the output terminal, and the antenna; and
additional control circuitry configured to control the transmit/receive switch to:
couple the output terminal to the antenna when the apparatus is in transmit mode; and
couple the input terminal to the antenna when the apparatus is in receive mode.
11 . The apparatus of claim 1 , wherein the apparatus comprises a software-enabled access point (SoftAP).
12 . The apparatus of claim 1 , wherein the apparatus comprises in a wireless router.
13 . A transceiver chip comprising:
an input terminal configured to receive an input RF signal;
an output terminal separate from the input terminal and configured to transmit an output RF signal;
a power amplifier coupled to the output terminal to generate the output RF signal;
a low noise amplifier coupled to the input terminal to amplify the input RF signal;
a shunt switch coupled in parallel with the low noise amplifier between the input terminal and ground; and
a control circuitry to activate the shunt switch to couple the input terminal to ground when the power amplifier is turned on.
14 . The transceiver chip of claim 13 , wherein the power amplifier is a differential amplifier, the transceiver chip further comprising a magnetic balun coupled between an output of the differential amplifier and the output terminal.
15 . The transceiver chip of claim 13 , wherein the power amplifier is a single-ended amplifier, the transceiver chip further comprising an inductive load or RF choke coupled between an output of the single-ended amplifier and the output terminal.
16 . The transceiver chip of claim 13 , further comprising an Electrostatic Discharge (ESD) protection circuit coupled in parallel with the low noise amplifier between the input terminal and ground.
17 . The transceiver chip of claim 13 , wherein the transceiver chip is implemented in a software-enabled access point (SoftAP).
18 . The transceiver chip of claim 13 , wherein the transceiver chip is implemented in a wireless router.
19 . A method of operating a transceiver, comprising:
activating a power amplifier during a transmit mode to generate an output RF signal;
prior to activating the power amplifier, closing a shunt switch to couple an input of a low noise amplifier to ground;
deactivating the power amplifier during a receive mode; and
after deactivating the power amplifier, opening the shunt switch to enable the low noise amplifier to receive an RF input signal.
20 . The method of claim 19 , wherein the power amplifier, the low noise amplifier, and the shunt switch are disposed on a same integrated circuit die.