Transistor-based radio frequency (RF) switch

• US 10,608,623 B2
• Filed: 05/03/2019
• Issued: 03/31/2020
• Est. Priority Date: 12/21/2016
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Inventors: Kerr, Daniel Charles, Choi, Jinsung, Scott, Baker, Maxim, George, Oshima, Hideya
• Primary Examiner(s): Luu, An T
• Application Number:
  US16/402,512
• Publication Number:
  US 20190260366A1
• Time in Patent Office: 333 Days
• CPC Class Codes: H03K 17/04106 in field-effect transistor switches H03K17/0412, H03K17/0416 take precedence
• CPC Class Codes: H03K 17/04206 in field-effect transistor switches
• CPC Class Codes: H03K 17/102 in field-effect transistor switches
• CPC Class Codes: H03K 2217/0018 Special modifications or use of the back gate voltage of a FET
• CPC Class Codes: H04B 1/44 Transmit/receive switching
• 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

A transistor-based radio frequency (RF) switch that provides symmetric RF impedance is disclosed. The transistor-based RF switch includes an N number of main field-effect transistors (FETs) stacked in series between a first end node and a second end node. A first end-network is coupled between the first end node and a proximal gate node. The first end-network provides a first variable impedance that equalizes a drain-to-source voltage of the first main FET to within a predetermined percentage of a drain-to-source voltage of a second main FET of the N number of main FETs. A second end-network is coupled between the second end node and the distal gate node, wherein the second end-network provides a second variable impedance to equalize the drain-to-source voltage of an Nth main FET to within the predetermined percentage of the drain-to-source voltage of an N−1 main FET of the N number of main FETs.

Claims

1. A transistor-based radio frequency (RF) switch comprising:

an N number of main field-effect transistors (FETs) stacked in series between a first end node and a second end node such that a first terminal of a first main FET of the N number of main FETs is coupled to the first end node and a second terminal of an Nth main FET of the N number of main FETs is coupled to the second end node, wherein N is a finite integer greater than two;

a plurality of gate resistors coupled in series between a proximal gate node and a distal gate node, wherein each gate resistor of the plurality of gate resistors is coupled between gates of an adjacent pair of the N number of main FETs;

a first end-network coupled between the first end node and the proximal gate node, wherein the first end-network provides a first variable impedance that equalizes a drain-to-source voltage of the first main FET of the N number of main FETs to within ±

5% of a drain-to-source voltage of a second main FET of the N number of main FETs; and

a second end-network coupled between the second end node and the distal gate node, wherein the second end-network provides a second variable impedance to equalize the drain-to-source voltage of an Nth main FET of the N number of main FETs to within ±

5% of the drain-to-source voltage of an N−

1 main FET of the N number of main FETs.

2. The transistor-based RF switch of claim 1 wherein the first end-network comprises a first network resistor coupled in series with a first variable capacitor that together provide the first variable impedance, and the second end-network comprises a second network resistor coupled in series with a second variable capacitor that together provide the second variable impedance.

3. The transistor-based RF switch of claim 2 wherein the first variable capacitor and the second variable capacitor are accumulation-type varactor diodes.

4. The transistor-based RF switch of claim 2 wherein the first network resistor and the second network resistor each have resistance values that are within ±

5% one half an average resistance value of individual ones of the plurality of gate resistors.

5. The transistor-based RF switch of claim 2 further including a body bias network having a plurality of body resistors coupled in series between a proximal body node and a distal body node, wherein each body resistor of the plurality of body resistors is coupled between body terminals of an adjacent pair of the N number of main FETs.

6. The transistor-based RF switch of claim 5 further comprising:

a third end-network coupled between the first end node and the proximal body node, wherein the third end-network provides a third variable impedance that further equalizes the drain-to-source voltage of the first main FET of the N number of main FETs to within ±

5% of the drain-to-source voltage of the second main FET of the N number of main FETs; and

a fourth end-network coupled between the second end node and the distal body node, wherein the fourth end-network provides a fourth variable impedance to further equalize the drain-to-source voltage of the Nth main FET of the N number of main FETs to within ±

5% of the drain-to-source voltage of the N−

1 main FET of the N number of main FETs.

7. The transistor-based RF switch of claim 6 wherein the third end-network comprises a third network resistor coupled in series with a third variable capacitor that together provide the third variable impedance, and the fourth end-network comprises a fourth network resistor coupled in series with a fourth variable capacitor that together provide the fourth variable impedance.

8. The transistor-based RF switch of claim 7 wherein the third variable capacitor and the fourth variable capacitor are accumulation-type varactor diodes.

9. The transistor-based RF switch of claim 7 wherein the third network resistor and the fourth network resistor each have resistance values that are within ±

5% one half an average resistance value of individual ones of the plurality of body resistors.

10. The transistor-based RF switch of claim 7 further including a plurality of acceleration switches coupled across corresponding ones of the plurality of gate resistors.

11. The transistor-based RF switch of claim 10 further including an acceleration bias network having a plurality of acceleration resistors coupled in series between a proximal acceleration node and a distal acceleration node, wherein each acceleration resistor of the plurality of acceleration resistors is coupled between switch control terminals of adjacent ones of the plurality of acceleration switches.

12. The transistor-based RF switch of claim 11 further comprising:

a fifth end-network coupled between the first end node and the proximal acceleration node, wherein the fifth end-network provides a fifth variable impedance that further equalizes the drain-to-source voltage of the first main FET of the N number of main FETs to within ±

5% of the drain-to-source voltage of the second main FET of the N number of main FETs; and

a sixth end-network coupled between the second end node and the distal acceleration node, wherein the sixth end-network provides a sixth variable impedance to further equalize the drain-to-source voltage of the Nth main FET of the N number of main FETs to within ±

5% of the drain-to-source voltage of the N−

1 main FET of the N number of main FETs.

13. The transistor-based RF switch of claim 12 wherein the fifth end-network comprises a fifth network resistor coupled in series with a fifth variable capacitor that together provide the fifth variable impedance, and the sixth end-network comprises a sixth network resistor coupled in series with a sixth variable capacitor that together provide the sixth variable impedance.

14. The transistor-based RF switch of claim 13 wherein the fifth variable capacitor and the sixth variable capacitor are accumulation-type varactor diodes.

15. The transistor-based RF switch of claim 13 wherein the fifth network resistor and the sixth network resistor each have resistance values that are within ±

5% one half an average resistance value of individual ones of the plurality of acceleration resistors.

16. The transistor-based RF switch of claim 13 wherein the first variable capacitor, the second variable capacitor, the third variable capacitor, the fourth variable capacitor, the fifth variable capacitor, and the sixth variable capacitor have lower capacitance when the transistor-based RF switch is an on-state and a higher capacitance when the transistor-based RF switch is in an off-state.

17. The transistor-based RF switch of claim 10 further including a first end acceleration switch coupled across the first network resistor, wherein a gate of the first end acceleration switch is coupled to the first end node.

18. The transistor-based RF switch of claim 10 further including a second end acceleration switch coupled across the second network resistor, wherein a gate of the second end acceleration switch is coupled to the second end node.

19. The transistor-based RF switch of claim 10 further including a first end acceleration switch coupled across the first network resistor and a second end acceleration switch coupled across the second network resistor, wherein a gate of the first end acceleration switch is coupled to the first end node and a gate of the second end acceleration switch is coupled to the second end node.

20. The transistor-based RF switch of claim 19 wherein the plurality of acceleration switches are p-FETs.