Resonant radio frequency switch

• US 9,479,160 B2
• Filed: 12/17/2014
• Issued: 10/25/2016
• Est. Priority Date: 12/17/2014
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: GlobalFoundries, Inc.
• Inventors: Srihari, Srikanth, Vanukuru, Venkata N. R.
• Primary Examiner(s): Bilodeau, David
• Application Number:
  US14/573,238
• Publication Number:
  US 20160182037A1
• Time in Patent Office: 678 Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/50 Structural association of antennas with earthing switches, lead-in devices or lightning protectors
• CPC Class Codes: H03K 17/687 the devices being field-effect transistors
• CPC Class Codes: H03K 17/693 Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors logic circuits H03K19/00; code converters H03M5/00, H03M7/00
• CPC Class Codes: H04B 1/48 in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter H04B1/46 takes precedence

Abstract

An SPDT switch in a RF communication transceiver provides for choosing the transmit/receive path for the RF signal. It consists of the series and shunt branches each consisting of stack of FETs. Performance metrics of the RF switch are insertion loss and isolation. At high frequency, the device/FET capacitance and the parasitic capacitances provide a leakage path for the signal, resulting in higher insertion loss and lower isolation. A parallel resonant LC network across each of the series and/or shunt branch FETs in a SPDT switch provides lower insertion loss, higher switch isolation, and lower out of band harmonics when compared to that of the state of the art SPDT switch. A method to reduce the form factor of such switch configuration is disclosed which is useful in wireless front end modules.

Claims

1. Circuitry comprising:

a first switch;

a second switch;

a first inductor/capacitor (LC) network; and

a second LC network;

wherein;

the first switch is connected between a first high frequency terminal and a second high frequency terminal;

the first LC network is connected in parallel across the first switch;

the second switch is connected between the first high frequency terminal and a first low frequency terminal;

the second LC network is connected in parallel across the second switch; and

the first and second switches are controlled so that the first and second switches have different ON/OFF status during operation of the circuitry.

2. The circuitry of claim 1, wherein:

the first switch includes a field effect transistor; and

the second switch includes a field effect transistor.

3. The circuitry of claim 1 wherein:

the first inductor/capacitor (LC) network is configured to resonate such that a capacitance of the first switch is essentially cancelled out; and

the second LC network is configured to resonate such that a capacitance of the second switch is essentially cancelled out.

4. The circuitry of claim 1, wherein the first and second LC networks each have a large capacitance reducing an inductance value required for a resonance condition.

5. The circuitry of claim 1, wherein the first LC network includes a first inductor and a second inductor, the first inductor arranged in parallel with the second inductor.

6. Circuitry comprising:

a first series switch and a first shunt switch controlled such that the first series switch and the first shunt switch have different ON/OFF status during operation of the circuitry;

a second series switch and a second shunt switch controlled such that the second series switch and the second shunt switch have different ON/OFF status during operation of the circuitry;

the first series switch and the second series switch controlled so that the first series switch and the second series switch have different ON/OFF status during operation of the circuitry; and

a first resonant circuit in parallel with the first series switch.

7. The circuitry of claim 6, further comprising:

a multi-port inductor arranged to resonate a first series/shunt branch and a second series shunt branch;

wherein;

the first series/shunt branch includes the first series switch and the first shunt switch; and

the second series/shunt branch includes the second series switch and the second shunt switch.

8. The circuitry of claim 6, further comprising:

an RF antenna in series with the first series switch and the second series switch.

9. The circuitry of claim 8, wherein:

the RF antenna is located between the first series switch and the second series switch; and

the first series switch and the first shunt switch are arranged as a mirror image about the RF antenna to match an arrangement of the second series switch and the second shunt switch.

10. The circuitry of claim 6, further comprising:

a second resonant circuit in parallel with the second series switch.

11. The circuitry of claim 10, wherein the first resonant circuit includes a first inductor in parallel with a second inductor.

12. The circuitry of claim 10, further comprising:

a third resonant circuit in parallel with the first shunt switch; and

a fourth resonant circuit in parallel with the second shunt switch.

13. The circuitry of claim 12, wherein the third resonant circuit includes a third inductor in parallel with a fourth inductor.

14. Circuitry comprising:

an RF antenna in series with a first terminal and a second terminal, the RF antenna between the first terminal and the second terminal;

a first series switch in series between the RF antenna and the first terminal;

a first shunt switch in between the first terminal and a low-frequency terminal;

the first series switch and the first shunt switch controlled such that the first series switch and the first shunt switch have different ON/OFF status during operation of the circuitry;

a second series switch in series between the RF antenna and the second terminal;

a second shunt switch in between the second terminal and a low-frequency terminal;

the second series switch and the second shunt switch controlled such that the second series switch and the second shunt switch have different ON/OFF status during operation of the circuitry;

a first resonant circuit in parallel with the first series switch and the first shunt switch; and

a second resonant circuit in parallel with the second series switch and the second shunt switch;

wherein;

the first terminal is a communication-receiving terminal; and

the second terminal is a communication-transmitting terminal.

15. The circuitry of claim 14, wherein the first series switch and the second series switch are controlled so that the first series switch and the second series switch have different on/off status during operation of the circuitry.

16. The circuitry of claim 14, wherein the first series switch and the first shunt switch are arranged in a configuration that mirrors, about the RF antenna, the configuration of the second series switch and the second shunt switch.

17. The circuitry of claim 14, further comprising:

a third resonant circuit in parallel with the first shunt switch; and

a fourth resonant circuit in parallel with the second shunt switch.

18. The circuitry of claim 14, wherein:

the first resonant circuit includes a first inductor in parallel with a second inductor.

19. The circuitry of claim 14, further comprising:

a multi-port inductor arranged to resonate a first series/shunt branch and a second series shunt branch;

wherein;

the first series/shunt branch includes the first series switch and the first shunt switch; and

the second series/shunt branch includes the second series switch and the second shunt switch.