Transmit-receive isolation in a transformer-based radio frequency power amplifier

Patent metadata

Field	Value
Publication number	US-2016226552-A1
Application number	US-201514983256-A
Country	US
Kind code	A1
Filing date	Dec 29, 2015
Priority date	Dec 30, 2014
Publication date	Aug 4, 2016
Grant date	—

Abstract

Embodiments of radio frequency (RF) systems include a transmit/receive switch integrated with one or more power amplifiers and/or other components. The power amplifiers can have transformer-based architectures. A compensation circuit can act to protect the receive path during an RF transmit mode.

First claim

What is claimed is:

1 . A radio frequency (RF) device comprising:
an antenna; a receive path configured to process RF receive signals detected by the antenna; a switch positioned between a node in the receive path and a reference voltage such that the switch creates a low impedance path between the node and the reference voltage when the switch is on in an RF transmit mode and creates a high impedance path to the reference voltage when the switch is off in an RF receive mode; and a compensation circuit connected in series with the switch in a path extending from the switch to the reference voltage, the compensation circuit acting to limit a voltage swing present at the node in the receive path when the switch is closed in the RF transmit mode.

2 . The RF device of claim 1 wherein the compensation circuit includes a capacitor.

3 . The RF device of claim 1 wherein the compensation circuit counteracts a reactance of a bond wire residing in the path between the switch and the reference voltage.

4 . The RF device of claim 1 further comprising a power amplifier, the switch, the compensation circuit, and the power amplifier being integrated together on a semiconductor die with the power amplifier.

5 . The RF device of claim 4 wherein the compensation circuit resides on the semiconductor die between a first terminal of the switch and a bond pad of the semiconductor die.

6 . The RF device of claim 5 wherein the node in the receive path is electrically coupled to a second terminal of the switch and to a receive port of the semiconductor die.

7 . The RF device of claim 6 wherein the power amplifier outputs an amplified RF transmit signal for delivery to the antenna when the RF device is in the RF transmit mode, the compensation circuit improving isolation between the receive path and the RF transmit signal when the RF device is in the RF transmit mode.

8 . The RF device of claim 4 wherein the power amplifier is a distributed active transformer-based power amplifier including a primary winding and a secondary winding.

9 . The RF device of claim 8 wherein the geometry of the secondary winding generally matches the geometry of the primary winding.

10 . The RF device of claim 9 wherein the primary winding has an inner winding generally conforming to an interior boundary of the secondary winding and an outer winding generally conforming to an exterior boundary of the secondary winding.

11 . The RF device of claim 8 wherein the primary winding receives a set of bias signals having a first set of values in the RF transmit mode to bias the primary winding in a first state and having a second set of values in the RF receive mode to bias the primary winding in a second state in which the primary and secondary windings are detuned with respect to one another.

12 . A semiconductor die comprising:
a power amplifier configured to output an RF transmit signal; a receive path configured to communicate and process an RF receive signal; a switch positioned between a node in the receive path and a pad of the semiconductor die such that the switch creates a low impedance path between the node and the pad when the switch is on in an RF transmit mode and creates a high impedance path to the pad when the switch is off in an RF receive mode; and a compensation circuit connected in series with the switch in a path extending from the switch to the pad, the compensation circuit acting to limit a voltage swing present at the node in the receive path when the switch is closed in the RF transmit mode.

13 . The semiconductor die of claim 12 wherein the power amplifier is a distributed active transformer-based power amplifier including a primary winding and a secondary winding.

14 . The semiconductor die of claim 13 wherein the geometry of the secondary winding generally matches the geometry of the primary winding.

15 . The semiconductor die of claim 14 wherein the primary winding has an inner winding generally conforming to an interior boundary of the secondary winding and an outer winding generally conforming to an exterior boundary of the secondary winding.

16 . The semiconductor die of claim 12 wherein the compensation circuit includes a capacitor.

17 . The semiconductor die of claim 12 wherein the compensation circuit counteracts a reactance of a bond wire residing in a path between the switch and the pad.

18 . A method of operating a radio frequency (RF) device, the method comprising:
when the RF device is in an RF transmit mode,
providing an RF transmit signal to a power amplifier of the RF device;
amplifying the RF transmit signal with the power amplifier to provide an amplified version of the RF transmit signal;
controlling a transmit/receive switch to create a low impedance path from a node in a receive path of the RF device to a reference voltage; and
with a compensation circuit positioned between the switch and the reference voltage, limiting a voltage swing present at the node in the receive path due to leakage of the RF transmit signal.

19 . The method of claim 18 wherein the compensation circuit includes a capacitor.

20 . The method of claim 19 wherein the compensation circuit limits the voltage swing by counteracting a reactance of a wire in the path between the switch and the reference voltage.

Assignees

• Skyworks Solutions Inc

Inventors

• Jin Yalin
• Mohta Setu

Classifications

• H03F2200/102

  A non-specified detector of a signal envelope being used in an amplifying circuit · CPC title

• H03F3/601

  using FET's, e.g. GaAs FET's (H03F3/607, H03F3/608 take precedence) · CPC title

• H03F2200/423

  Amplifier output adaptation especially for transmission line coupling purposes, e.g. impedance adaptation · CPC title

• H04B1/525

  with means for reducing leakage of transmitter signal into the receiver · CPC title

• H03F2200/537

  A transformer being used as coupling element between two amplifying stages · CPC title