Low power consumption binary phase shift keyed (BPSK) modulator using absorptive electronic switching techniques

• US 5,455,543 A
• Filed: 01/28/1994
• Issued: 10/03/1995
• Est. Priority Date: 01/28/1994
• Status: Expired due to Term

• Current Assignee: Thomson Consumer Electronics Incorporated (Vantiva SA)
• Original Assignee: Thomson Consumer Electronics Incorporated (Vantiva SA)
• Inventors: Kechkaylo, David L.
• Primary Examiner(s): Pascal, Robert J.
• Assistant Examiner(s): KINKEAD, ARNOLD M
• Application Number:
  US08/188,640
• Time in Patent Office: 613 Days
• Field of Search: 332/103, 332/104, 332/105, 375/17, 375/52-55, 375/67, 375/83, 375/86, 375/87, 375/279, 375/280, 375/281, 375/282, 375/308, 375/329, 375/332, 375/333, 375/200
• US Class Current: 332/103
• CPC Class Codes: H03C 3/40 using two signal paths the outputs of which have a predetermined phase difference and at least one output being amplitude-modulated
• CPC Class Codes: H03D 7/14 Balanced arrangements
• CPC Class Codes: H04L 27/2035 using a single or unspecified number of carriers

Abstract

A low power consumption BPSK modulator uses only one center-tapped transformer and a single-pole double-throw (SPDT) switching arrangement including four field effect transistors and a pair of termination resistors. An advantage of the subject invention is that the DC switching current is reduced by a factor of approximately 1500 with respect to a conventional diode ring modulator. An extremely important advantage of the subject invention in the field of handheld battery-powered communications equipment is that the subject apparatus can be made relatively small due to the necessity for only one transformer.

Claims

1. A low power consumption biphase modulator, comprising:

an input terminal for receiving an input RF signal of a predetermined phase;

an output terminal for developing an RF signal in phase with respect to said input RF signal or substantially 180-degrees out of phase with respect to said input RF signal;

a transformer having a primary winding coupled to said input terminal for receiving said input RF signal, and having a secondary winding including first and second ends and a centertap for developing at opposite ones of said first and second ends said in-phase and out-of-phase RF signals, said centertap being coupled to a point of reference potential; and

a switch array exhibiting first and second states in response to a control signal, in said first state said switch array couples said first end of said secondary winding to said output terminal for developing said in-phase RF signal and couples said second end of said secondary winding to a source of reference potential through a first termination impedance and in said second state, said switch array couples said second end of said secondary winding to said output terminal for developing said out-of-phase signal and couples said first end of said secondary winding to a source of reference potential through a second termination impedance;

said switch array having a control terminal for receiving said control signal for controlling which of said in-phase and out-of-phase RF signal is selected;

said biphase modulator including no transformer other than said transformer having said centertap.

2. A low power consumption biphase modulator, comprising:

an input terminal for receiving an input RF signal of a predetermined phase;

an output terminal for developing an RF signal in phase with respect to said input RF signal or substantially 180-degrees out of phase with respect to said input RF signal;

a transformer having a primary winding coupled to said input terminal for receiving said input RF signal, and having a secondary winding including first and second ends and a centertap for developing at opposite ones of said first and second ends said in-phase and out-of-phase RF signals, said centertap being coupled to a point of reference potential; and

an FET switch array exhibiting first and second states in response to a control signal, in said first state said FET switch array couples said first end of said secondary winding to said output terminal for developing said in-phase RF signal and couples said second end of said secondary winding to a source of reference potential through a first termination impedance and in said second state, said FET switch array couples said second end of said secondary winding to said output terminal for developing said out-of-phase signal and couples said first end of said secondary winding to a source of reference potential through a second termination impedance;

said FET switch array having a control terminal for receiving said control signal for controlling which of said in-phase and out-of-phase RF signals is selected;

said biphase modulator including no transformer other than said transformer having said centertap.

3. The low power consumption biphase modulator of claim 2 wherein,

said FET switch array is a JFET array.

4. The low power consumption biphase modulator of claim 2 wherein,

said FET switch array comprises four GaAs JFETs.

5. The low power consumption biphase modulator of claim 2 wherein,

said FET switch array comprises four MOSFETs.

6. In direct sequence spread spectrum battery-powered communications equipment, a low power consumption biphase modulator, comprising:

an input terminal for receiving a 900 MHz RF carrier signal of a predetermined phase;

an output terminal for developing an RF signal in phase with respect to said input RF signal or substantially 180-degrees out of phase with respect to said input RF signal;

a transformer having a primary winding coupled to said input terminal for receiving said 900 MHz RF carrier signal, and having a secondary winding including first and second ends and a centertap for developing at opposite ones of said first and second ends said in-phase and out-of-phase RF carrier signals with respect to said centertap, said centertap being coupled to a point of reference potential; and

an FET switch array exhibiting first and second states in response to a control signal, in said first state said FET switch array couples said first end of said secondary winding to said output terminal for developing said in-phase RF signal and couples said second end of said secondary winding to a source of reference potential through a first termination impedance and in said second state, said FET switch array couples said second end of said secondary winding to said output terminal for developing said out-of-phase signal and couples said first end of said secondary winding to a source of reference potential through a second termination impedance;

said FET switch array having a control terminal for receiving said control signal for controlling which of said in-phase or out-of-phase carrier signals is selected, said control signal being a combination of a binary representation of speech and a spreading code;

said biphase modulator including no transformer other than said transformer having said centertap.

7. A low power consumption quadraphase modulator, comprising:

an input terminal for receiving an input RF signal of a predetermined phase;

an output terminal for developing an RF signal which is one of in phase with respect to said input RF signal, 90-degrees out-of-phase with respect to said input RF signal, 180-degrees out-of-phase with respect to said input RF signal, and 270-degrees out-of-phase with respect to said input RF signal;

a quadrature phase network for developing first and second RF signals having a 90-degree phase shift between them;

a first transformer having a primary winding coupled to said input terminal for receiving said input RF signal, and having a secondary winding including first and second ends and a centertap for developing at opposite ones of said first and second ends said in-phase and said 180-degree-out-of-phase RF signals, said centertap being coupled to a point of reference potential; and

a second transformer having a primary winding coupled to said quadrature phase network for receiving said RF signal having a 90-degree phase shift with respect to said input RF signal, and having a secondary winding including first and second ends and a centertap for developing at opposite ones of said first and second ends said 90-degree out-of-phase and 270-degree out-of-phase RF signals, said centertap being coupled to a point of reference potential; and

a first switch array exhibiting first and second states in response to a first control signal, in said first state said first switch array couples said first end of said secondary winding of said first transformer to said output terminal for developing said in-phase RF signal and couples said second end of said secondary winding of said first transformer to a source of reference potential through a first termination impedance, and in said second state said first switch array couples said second end of said secondary winding of said first transformer to said output terminal for developing said 180-degree-out-of-phase signal and couples said first end of said secondary winding of said first transformer to a source of reference potential through a second termination impedance;

a second switch array exhibiting third and fourth states in response to a second control signal, in said third state said second switch array couples said first end of said secondary winding of said second transformer to said output terminal for developing said 90-degree out-of-phase RF signal and couples said second end of said secondary winding of said second transformer to a source of reference potential through a third termination impedance, and in said fourth state said second switch array couples said second end of said secondary winding of said second transformer to said output terminal for developing said 270-degree-out-of-phase signal and couples said first end of said secondary winding of said second transformer to a source of reference potential through a fourth termination impedance;

each of said first and second switch arrays having a control terminal for receiving a respective one of first and second control signals for controlling which of said phases of said RF signal is selected;

said biphase modulator including no output transformer.