Dual mode radiotelephone modulator

• US 5,764,692 A
• Filed: 12/16/1996
• Issued: 06/09/1998
• Est. Priority Date: 09/09/1994
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Mucke, Lars H.
• Primary Examiner(s): Vo, Don N.
• Assistant Examiner(s): Le, Amanda T.
• Application Number:
  US08/767,289
• Time in Patent Office: 540 Days
• Field of Search: 455/403, 455/550, 455/552, 455/553, 455/573, 455/93, 455/95
• US Class Current: 375/216
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453

Abstract

A dual-mode frequency and phase RF modulator (11) for use in a transmitter of a radiotelephone. A dual-mode modulation approach is employed wherein, in the analog (FM) mode of operation, a phase modulator, such as a π/4-shift DQPSK modulator, is bypassed and may be powered down. A frequency modulated RF carrier is coupled through a bypass circuit (52) to a modulator output node (50) for transmission from the radiotelephone. In the digital mode of operation, the bypass signal path is disabled, the π/4-shift DQPSK modulator is enabled, and in-phase (I) and quadrature (Q) signals are input to the π/4-shift DQPSK modulator which provides a phase modulated RF carrier that is coupled to the modulator output node for transmission from the radiotelephone. The teaching of this invention can be employed with radiotelephones having, by example, TDMA/analog capability or CDMA/analog capability.

Claims

1. A dual-mode modulator having an output node, comprising:

means, responsive to a first state of a control signal, for phase modulating an RF signal, said phase modulating means having an output coupled to the output node;

means, responsive to a second state of the control signal, for frequency modulating said RF signal in accordance with a frequency modulation input signal and, responsive to said first state of the control signal wherein said frequency modulation input signal is set to a predetermined state, for outputting said RF signal as an unmodulated RF signal to said phase modulating means; and

means, responsive to the second state of the control signal, for coupling an output of said frequency modulating means to the output node so as to bypass said phase modulating means.

2. A dual-mode modulator having an output node, comprising:

means, responsive to a first state of a control signal, for phase modulating an RF signal, said phase modulating means comprising at least first and second frequency mixers and having an output coupled to the output node;

means, responsive to a second state of the control signal, for frequency modulating said RF signal in accordance with a frequency modulation input signal and, responsive to said first state of the control signal wherein said frequency modulation input signal is set to a predetermined state, for outputting said RF signal as an unmodulated RF signal to said phase modulating means; and

means, responsive to the second state of the control signal, for coupling an output of said frequency modulating means to the output node for bypassing at least said first and second frequency mixers;

wherein said phase modulating means is responsive to the second state of the control signal for operating in a low power mode of operation.

3. A dual-mode modulator having an output node, comprising:

means, responsive to a first state of a control signal, for phase modulating an RF signal, said phase modulating means having an output coupled to the output node;

means, responsive to a second state of the control signal, for frequency modulating an RF signal; and

means, responsive to the second state of the control signal, for coupling an output of said frequency modulating means to the output node, wherein said coupling means is responsive to the first state of the control signal for operating in a low power mode of operation.

4. A radiotelephone, comprising:

control means for generating a first state of a control signal when operating the radiotelephone in a first mode of operation and for generating a second state of the control signal when operating the radiotelephone in a second mode of operation;

means, responsive to said control signal, for generating a first representation of an audio input signal when operating in the first mode of operation and for generating a second representation of the audio input signal when operating in the second mode of operation;

means, responsive to the first representation, for generating a first phase modulation control signal and a second phase modulation control signal; and

modulator means comprising means, responsive to the second representation, for frequency modulating a transmitter injection frequency signal in accordance with said second representation, said modulator means further comprising means, responsive to the first representation, for phase modulating the transmitter injection frequency signal in accordance with the first representation, said modulator means having an output node for outputting a transmission frequency signal that is modulated, in the first mode of operation, in accordance with said first representation and that is modulated, in the second mode of operation, in accordance with said second representation, said modulator means further comprising,

bypass means, responsive to said control signal, for coupling an output of said frequency modulation means to said output node in the second mode of operation by providing a separate signal path around said phase modulating means.

5. A radiotelephone as set forth in claim 4 wherein in said first mode of operation said radiotelephone operates in accordance with a Time Division-Multiple Access technique.

6. A radiotelephone as set forth in claim 4 wherein in said first mode of operation said radiotelephone operates in accordance with a Code Division-Multiple Access technique.

7. A radiotelephone, comprising:

control means for generating a first state of a control signal when operating the radiotelephone in a first mode of operation and for generating a second state of the control signal when operating the radiotelephone in a second mode of operation;

means, responsive to said control signal, for generating a first representation of an audio input signal when operating in the first mode of operation and for generating a second representation of the audio input signal when operating in the second mode of operation;

means, responsive to the first representation, for generating a first phase modulation control signal and a second phase modulation control signal;

means, responsive to the second representation, for frequency modulating a transmitter injection frequency signal in accordance therewith; and

modulator means having an output node for outputting a transmission frequency signal that is modulated, in the first mode of operation, in accordance with said first representation and that is modulated, in the second mode of operation, in accordance with said second representation, said modulator means comprising,

bypass means, responsive to said control signal, for coupling an output of said frequency modulation means to said output node in the second mode of operation;

wherein said modulator means is comprised of;

first and second frequency mixer means that are responsive to said first and second phase modulation control signals, respectively, for phase modulating said transmitter injection frequency signal in accordance therewith;

wherein

said first and said second frequency mixer means are responsive to said control signal for operating in a low power mode of operation when operating in the second operating mode; and

wherein

said bypass means is responsive to said control signal for operating in a low power mode of operation when operating in the first operating mode.

8. A dual-mode modulator having an output node, comprising:

means, responsive to a first mode of operation, for phase modulating an RF signal in accordance with an In-phase (I) input signal and a Quadrature (Q) input signal, said phase modulating means comprising at least first and second frequency mixers and having an output coupled to the output node and providing an Output signal given by,

space="preserve" listing-type="equation">Output=I Cos(ω

t+p1)+Q Cos(ω

t+p2),

where LO=cos(ω

t), t is time, and p1 and p2 are constants;

means, responsive to a second mode of operation, for frequency modulating said RF frequency signal in accordance with a frequency modulation input and providing an Output signal given by,

space="preserve" listing-type="equation">Output=A Cos(ω

t+m(t)+p),

where LO=Cos(ω

t+m(t)), A and p are constants, and m(t) is a function of the frequency modulation input, said frequency modulating means being responsive to said first mode of operation and said frequency modulation input being placed in a predetermined state for outputting said RF signal as an unmodulated RF signal to said phase modulating means; and

means, responsive to the second mode of operation, for bypass coupling said Output signal of said frequency modulating means around at least said first and second frequency mixers to the output node.

9. A dual-mode modulator having an output node, comprising:

means, responsive to a first mode of operation, for phase modulating an RF signal in accordance with an In-phase (I) input signal and a Quadrature (Q) input signal, said phase modulating means comprising at least first and second frequency mixers and having an output coupled to the output node and providing an Output signal given by,

space="preserve" listing-type="equation">Output=I Cos(ω

t+p1)+Q Cos(ω

t+p2),

where LO=cos(ω

t), t is time, and p1 and p2 are constants;

means, responsive to a second mode of operation, for frequency modulating said RF frequency signal in accordance with a frequency modulation input and providing an Output signal given by,

space="preserve" listing-type="equation">Output=A Cos(ω

t+m(t)+p),

where LO=Cos(ω

t+m(t)), A and p are constants, and m(t) is a function of the frequency modulation input, said frequency modulating means being responsive to said first mode of operation and said frequency modulation input being placed in a predetermined state for outputting said RF signal as an unmodulated RF signal to said phase modulating means; and

means, responsive to the second mode of operation, for coupling said Output signal of said frequency modulating means around at least said first and second frequency mixers to the output node;

wherein said phase modulating means is responsive to the second mode of operation for operating in a low power mode.

10. A dual-mode modulator having an output node, comprising:

means, responsive to a first mode of operation, for phase modulating an RF signal in accordance with an In-phase (I) input signal and a Quadrature (Q) input signal, said phase modulating means having an output coupled to the output node and providing an Output signal given by,

space="preserve" listing-type="equation">Output=I Cos(ω

t+p1)+Q Cos(ω

t+p22),

where LO=cos(ω

t), t is time, and p1 and p2 are constants;

means, responsive to a second mode of operation, for frequency modulating an RF frequency signal in accordance with a frequency modulation input and providing an Output signal given by,

space="preserve" listing-type="equation">Output=A Cos(ω

t+m(t)+p),

where LO=Cos(ω

t+m(t)), A and p are constants, and m(t) is a function of the frequency modulation input; and

means, responsive to the second mode of operation, for coupling said Output signal of said frequency modulating means to the output node;

wherein said coupling means is responsive to the first mode of operation for operating in a low power mode.

11. A dual-mode modulator having an output node, comprising:

means, responsive to a first mode of operation, for phase modulating an RF signal in accordance with an In-phase (I) input signal and a Quadrature (Q) input signal, said phase modulating means having an output coupled to the output node and providing a first output signal given by,

space="preserve" listing-type="equation">output=I Cos(ω

t+p1)+Q Cos(ω

t+p2),

where LO=cos(ω

t), t is time, and p1 and p2 are constants;

means, responsive to a second mode of operation, for frequency modulating an RF frequency signal in accordance with a frequency modulation input and providing a second output signal given by,

space="preserve" listing-type="equation">Output=A Cos(ω

t+m(t)+p),

where LO=Cos(ω

t+m(t)), A and p are constants, and m(t) is a function of the frequency modulation input; and

summing means having an output coupled to said output node and a first input coupled to said I Cos(ω

t+p1) component of said first output signal, a second input coupled to said Q Cos(ω

t+p2) component of said first output signal, and a third input coupled to said A Cos(ω

t+m(t)+p) component of said second output signal.

12. A dual-mode modulator as set forth in claim 11, wherein said modulator forms a portion of a radiotelephone, and wherein in said first mode of operation said radiotelephone operates in accordance with a Time Division-Multiple Access technique.

13. A dual-mode modulator as set forth in claim 11, wherein said modulator forms a portion of a radiotelephone, and wherein in said first mode of operation said radiotelephone operates in accordance with a Code Division-Multiple Access technique.