RF switching circuit for use in mobile communication systems

• US 7,161,197 B2
• Filed: 05/23/2005
• Issued: 01/09/2007
• Est. Priority Date: 05/31/2004
• Status: Expired due to Fees

• Current Assignee: Collabo Innovations, Inc. (Wi-LAN Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nakatsuka, Tadayoshi, Fukumoto, Shinji
• Primary Examiner(s): Dickey, Thomas L.
• Application Number:
  US11/134,333
• Publication Number:
  US 20050263799A1
• Time in Patent Office: 596 Days
• Field of Search: 257/266, 257/270, 257/E29.319
• US Class Current: 257/270
• CPC Class Codes: H01L 27/088 the components being field-effect transistors with insulated gate
• 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

Abstract

An RF switching circuit according to the present invention includes: a plurality of input/output terminals for inputting and outputting an RF signal; and a switch for opening and closing an electrical connection between the input/output terminals. The switch is constituted by a multi-gate field effect transistor including a plurality of gates located between source and drain spaced from each other on a semiconductor layer. A bias voltage is applied to an inter-gate region of the semiconductor layer between the gates. The bias voltage is equal to or lower than 90% of a high-level voltage, which is a voltage for turning the multi-gate field effect transistor ON, in a state where the multi-gate field effect transistor is ON, and is equal to or higher than 80% of the high-level voltage and equal to or lower than the high-level voltage in a state where the multi-gate field effect transistor is OFF.

Claims

1. An RF switching circuit, comprising:

a plurality of input/output terminals for inputting and outputting an RF signal;

a switch for opening and closing an electrical connection between the input/output terminals, and

a control line,

wherein the switch is constituted by a multi-gate field effect transistor including a plurality of gates located between source and drain spaced from each other on a semiconductor layer,

the number of said input/output terminals is three,

the RF switching circuit is an SPDT RF switching circuit including two said multi-gate field effect transistors each connected between each two of the input/output terminals,

a bias voltage is applied to an inter-gate region of the semiconductor layer between the gates,

the bias voltage is equal to or lower than 90% of a high-level voltage, which is a voltage for turning the multi-gate field effect transistor ON, in a state where the multi-gate field effect transistor is ON, and is equal to or higher than 80% of the high-level voltage and equal to or lower than the high-level voltage in a state where the multi-gate field effect transistor is OFF, and

the control line is connected between the gates of one of the multi-gate field effect transistors and the inter-gate region of the other multi-gate field effect transistor.

2. The RF switching circuit of claim 1, further comprising a diode provided between the control line and the inter-gate region, the diode having a cathode connected to the inter-gate region.

3. The RF switching circuit of claim 1, wherein the high-level voltage is a power supply voltage.