MODULATION CIRCUIT DEVICE, MODULATION METHOD AND RADIO COMMUNICATION DEVICE

• US 20070280374A1
• Filed: 07/02/2007
• Published: 12/06/2007
• Est. Priority Date: 07/08/2003
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsuura, Toru, Adachi, Hisashi, Udagawa, Masaharu
• Granted Patent: US 7,702,299 B2
• Time in Patent Office: Days
• US Class Current: 375/271
• CPC Class Codes: H03C 5/00 Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal H03C7/00 takes precedence
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/025 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 2203/7239 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers and shunting lines by one or more switch(es)
• CPC Class Codes: H04L 27/361 Modulation using a single or unspecified number of carriers, e.g. with separate stages of phase and amplitude modulation

Abstract

The amplitude modulator comprises: an angle modulator for angle-modulating a phase signal to be inputted; a waveform shaping means in which, (1) when the magnitude of an amplitude signal to be inputted becomes smaller than a first prescribed value, a waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes small becomes the first prescribed value; and/or (2) the waveform shaping means in which, when the magnitude of the amplitude signal to be inputted becomes larger than the second prescribed value which is larger than the first prescribed value, the waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes larger becomes the second prescribed value; and an amplitude modulator for amplitude modulating the signal of the output of the angle modulator by the signal of the output of the waveform shaping means.

Claims

1. A modulation circuit device, comprising:

an angle modulator for angle-modulating an input phase signal;

an amplitude shaping means for performing a non-linear filtering on an input amplitude signal; and

an amplitude modulator for amplitude-modulating an output signal from said angle modulator by an output amplitude signal from said amplitude shaping means,

wherein said performing the non-linear filtering of said amplitude shaping means is equivalent to at least one of

(1) when said input amplitude signal becomes smaller than a first lower limit value which is a positive constant number, both of the first order differential coefficient and the second order differential coefficient of a magnitude of said output amplitude signal generated by said amplitude shaping means with respect to a magnitude of said input amplitude signal are limited to a positive value or zero in a segment in which said input amplitude signal becomes smaller than said first lower limit value, while said output amplitude signal is limited to a value not less than a second lower limit value which is a positive constant number smaller than said first lower limit value and smaller than said first lower limit, and

(2) when said input amplitude signal becomes larger than a first upper limit value which is a positive constant number, (a) the first order differential coefficient of a magnitude of said output amplitude signal generated by said amplitude shaping means with respect to a magnitude of said input amplitude signal is limited to a positive value or zero in a segment in which said input amplitude signal becomes larger than said first upper limit value, and (b) the second order differential coefficient of the magnitude of said output amplitude signal generated by said amplitude shaping means with respect to the magnitude of said input amplitude signal is limited to a negative value or zero in the segment in which said input amplitude signal becomes larger than said first upper limit value, while said output amplitude signal is limited to a value not more than a second upper limit value which is a constant number larger than said first upper limit value and larger than said first upper limit value.

2. The modulation circuit device according to claim 1, further comprising:

a table recording said input amplitude signal in correspondence with said output amplitude signal, p1 wherein said amplitude shaping means performs said non-linear filtering by using said table for said input amplitude signal, and outputs said output amplitude signal to said amplitude modulator.

3. A radio communication circuit, comprising:

a transmission circuit for outputting a transmission signal; and

a receiving circuit for outputting a receiving signal,

wherein said transmission circuit uses said modulation circuit device according to claim 1.

5. A radio communication circuit, comprising:

a transmission circuit for outputting a transmission signal; and

a receiving circuit for outputting a receiving signal,

wherein said transmission circuit uses said modulation circuit device according to claim 2.

4. A modulation method, comprising:

an angle modulation step of angle-modulating a phase signal to be inputted;

an amplitude shaping step of performing a non-linear filtering on an amplitude signal to be inputted; and

an amplitude modulation step of amplitude-modulating an output signal angle-modulated at said angle modulation step by an output amplitude signal performed with the non-linear filtering at said amplitude shaping step,

wherein said performing the non-linear filtering of said amplitude shaping step is equivalent to at least one of

(1) when said input amplitude signal becomes smaller than a first lower limit value which is a positive constant number, both of the first order differential coefficient and the second order differential coefficient of a magnitude of said output amplitude signal generated by said amplitude shaping means with respect to a magnitude of said input amplitude signal are limited to a positive value or zero in a segment in which said input amplitude signal becomes smaller than said first lower limit value, while said output amplitude signal is limited to a value not less than a second lower limit value which is a positive constant number smaller than said first lower limit value and smaller than said first lower limit, and

(2) when said input amplitude signal becomes larger than a first upper limit value which is a positive constant number, (a) the first order differential coefficient of a magnitude of said output amplitude signal generated by said amplitude shaping means with respect to a magnitude of said input amplitude signal is limited to a positive value or zero in a segment in which said input amplitude signal becomes larger than said first upper limit value, and (b) the second order differential coefficient of the magnitude of said output amplitude signal generated by said amplitude shaping means with respect to the magnitude of said input amplitude signal is limited to a negative value or zero in the segment in which said input amplitude signal becomes larger than said first upper limit value, while said output amplitude signal is limited to a value not more than a second upper limit value which is a constant number larger than said first upper limit value and larger than said first upper limit value.