RF circuit with switch transistor with body connection

• US 9,503,074 B2
• Filed: 03/06/2015
• Issued: 11/22/2016
• Est. Priority Date: 03/06/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Aubain, Max Samuel, Kemerling, Clint
• Primary Examiner(s): Zweizig, Jeffrey
• Application Number:
  US14/640,377
• Publication Number:
  US 20160261262A1
• Time in Patent Office: 627 Days
• US Class Current: 1/1
• CPC Class Codes: H03K 17/102 in field-effect transistor switches
• CPC Class Codes: H03K 17/162 without feedback from the output circuit to the control circuit
• CPC Class Codes: H03K 17/30 Modifications for providing a predetermined threshold before switching shaping pulses by thresholding H03K5/08
• CPC Class Codes: H03K 17/687 the devices being field-effect transistors
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor
• 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: H03K 2217/0018 Special modifications or use of the back gate voltage of a FET
• CPC Class Codes: H03K 3/01 Details

Abstract

In some method and apparatus embodiments, an RF circuit comprises a switch transistor having a source, a drain, a gate, and a body. A gate control voltage is applied to the gate of the switch transistor. A body control voltage is applied to the body of the switch transistor. The body control voltage is a positive bias voltage when the switch transistor is in an on state. In some embodiments, an RF circuit comprises a control voltage applied to the gate of the switch transistor through a first resistance and applied to the body of the switch transistor through a second resistance. The first resistance is different from the second resistance.

Claims

1. A method comprising:

applying a gate control voltage to a gate of a switch transistor in an RF circuit;

applying a body control voltage to a body of the switch transistor, wherein the body control voltage is a positive bias voltage when the switch transistor is in an on state;

wherein the gate control voltage is applied from a first voltage control source to the gate; and

wherein the body control voltage is applied from a second voltage control source to the body, further wherein the second voltage control source is independent from the first voltage control source.

2. The method of claim 1, wherein:

the positive bias voltage is greater than about 0.7 volts.

3. The method of claim 1, further comprising:

improving device linearity of the RF circuit by applying the positive bias voltage to the body of the switch transistor when the switch transistor is in the on state.

4. The method of claim 3, wherein:

the improved device linearity is a mitigated harmonic signal at three times a fundamental frequency of the RF circuit.

5. An RF circuit comprising:

a switch transistor comprising a source, a drain, a gate, and a body;

a first voltage control source configured to apply a gate control voltage to the gate; and

a second voltage control source, independent from the first voltage control source, configured to apply a body control voltage to the body such that the body control voltage is a positive bias voltage when the switch transistor is in an on state.

6. The RF circuit of claim 5, wherein:

the positive bias voltage is greater than 0.7 volts.

7. The RF circuit of claim 5, wherein:

the positive bias voltage is between 0.7 volts and about 5 volts.

8. The RF circuit of claim 5, wherein:

the first voltage control source comprises a first voltage level shifter coupled to a first positive voltage generator and a first negative voltage generator; and

the second voltage control source comprises a second voltage level shifter coupled to a second positive voltage generator and a second negative voltage generator.

9. The RF circuit of claim 5, wherein:

wherein the second voltage control source is configured to apply a negative bias voltage when the switch transistor is in an off state.