Waveform generator

• US 20020090036A1
• Filed: 12/12/2001
• Published: 07/11/2002
• Est. Priority Date: 01/10/2001
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsusaka, Hiromi
• Granted Patent: US 7,120,204 B2
• Time in Patent Office: Days
• US Class Current: 375/296
• CPC Class Codes: G06F 1/0321 Waveform generators, i.e. devices for generating periodical functions of time, e.g. direct digital synthesizers G06F1/0314, G06F1/035 take precedence
• CPC Class Codes: H03H 17/0607 comprising a ROM addressed by the input data signals

Abstract

A waveform generator comprises waveform generating means for generating a waveform signal band-limited using a first band limitation characteristic in accordance with the input signal series, memory means for storing in advance a difference signal between a waveform signal band-limited using the first band limitation characteristic for the input signal series and a waveform signal band-limited using a second band limitation characteristic for the input signal series and outputting the difference signal in accordance with the input signal series, adding means for adding a waveform signal from the waveform generating means to a difference signal from the memory means and outputting the signal band-limited using the second band limitation characteristic, and selector switch means for selectively outputting either a waveform signal from the waveform generating means or a waveform signal from the adding means.

Claims

1. A waveform generator operable in accordance with a plurality of band limitation characteristics, comprising:

waveform generating means for generating a waveform signal band-limited using a first band limitation characteristic in accordance with the input signal series;

memory means for storing in advance a difference signal between a waveform signal band-limited using the first band limitation characteristic for said input signal series and a waveform signal band-limited using a second band limitation characteristic for said input signal series and outputting said difference signal in accordance with said input signal series,

adding means for adding a waveform signal from said waveform generating means to a difference signal from said memory means and outputting the signal band-limited using the second band limitation characteristic; and

selector switch means for selectively outputting either a waveform signal from said waveform generating means or a waveform signal from said adding means.

2. A waveform generator operable in accordance with a plurality of band limitation characteristics, comprising:

first address generating means for generating address data in accordance with an input signal series;

first memory means for storing in advance waveform data showing the result of band limitation using a first band limitation characteristic and outputting said waveform data in accordance with address data from said first address generating means;

second address generating means for generating address data in accordance with said input signal series;

second memory means for storing in advance difference data between waveform data showing the result of band limitation using the first band limitation characteristic and waveform data showing the result of band limitation using the second band limitation characteristic and outputting said difference data in accordance with address data from said second address generating means;

digital adding means for adding waveform data from said first memory means to difference data from said second memory means and outputting waveform data showing the result of band limitation using the second band limitation characteristic;

digital-to-analog conversion means for converting either waveform data from said first memory means or waveform data from said digital adding means to an analog signal; and

filter means for removing an aliasing noise from the analog signal output from said digital-to-analog conversion means and outputting the resulting signal.

3. A waveform generator operable in accordance with a plurality of band limitation characteristics, comprising:

first address generating means for generating address data in accordance with an input signal series;

first memory means for storing in advance waveform data showing the result of band limitation using a first band limitation characteristic and outputting said waveform data in accordance with address data from said first address generating means;

first digital-to-analog conversion means for converting waveform data from said first memory means to an analog signal;

second address generating means for generating address data in accordance with said input signal series;

second memory means for storing in advance difference data between waveform data showing the result of band limitation using the first band limitation characteristic and waveform data showing the result of band limitation using the second band limitation characteristic and outputting said difference data in accordance with address data from said second address generating means;

second digital-to-analog conversion means for converting difference data from said second memory means to an analog signal;

analog adding means for adding an analog signal that is based on waveform data from said first digital-to-analog conversion means to an analog signal that is based on difference data from said second digital-to-analog conversion means and outputting an analog signal corresponding to the waveform data showing the result of band limitation using the second band limitation characteristic; and

filter means for removing an aliasing noise from either an analog signal output from said first digital-to-analog conversion means or an analog signal from said analog adding means and outputting the resulting signal.

4. A waveform generator operable in accordance with a plurality of band limitation characteristics, comprising:

first address generating means for generating address data in accordance with an input signal series;

first memory means for storing in advance, at a first data interpolation ratio, waveform data showing the result of band limitation using a first band limitation characteristic and outputting said waveform data in accordance with address data from said first address generating means;

first digital-to-analog conversion means for converting waveform data from said first memory means to an analog signal in a first clock cycle corresponding to the first data interpolation ratio;

second address generating means for generating address data in accordance with said input signal series;

second memory means for storing in advance, at a second data interpolation ratio, difference data between waveform data showing the result of band limitation using the first band limitation characteristic and waveform data showing the result of band limitation using the second band limitation characteristic and outputting said difference data in accordance with address data from said second address generating means;

second digital-to-analog conversion means for converting difference data from said second memory means to an analog signal in a first clock cycle corresponding to the second data interpolation ratio;

analog adding means for adding an analog signal that is based on waveform data from said first digital-to-analog conversion means to an analog signal that is based on difference data from said second digital-to-analog conversion means and outputting an analog signal corresponding to the waveform data showing the result of band limitation using the second band limitation characteristic;

first filter means for removing an aliasing noise from the analog signal output from said first digital-to-analog conversion means;

second filter means for removing an aliasing noise from the analog signal output from said analog adding means; and

selector switch means for selectively outputting either a signal from said first filter means or a signal from said second filter means.

5. A waveform generator operable in accordance with a plurality of band limitation characteristics, comprising:

first address generating means for generating address data in accordance with an input signal series;

first memory means for storing in advance, at a first data interpolation ratio, waveform data showing the result of band limitation using a first band limitation characteristic and outputting said waveform data in accordance with address data from said first address generating means;

second address generating means for generating address data in accordance with said input signal series;

second memory means for storing in advance, at a second data interpolation ratio, difference data between waveform data showing the result of band limitation using the first band limitation characteristic and waveform data showing the result of band limitation using the second band limitation characteristic and outputting said difference data in accordance with address data from said second address generating means;

interpolation filter means for converting a first data interpolation ratio for waveform data output from said first memory means;

digital adding means for adding waveform data converted at the said data interpolation ratio from said interpolation filter means to difference data from said second memory means and outputting waveform data showing the result of band limitation using the second band limitation characteristic;

digital-to-analog conversion means for converting either waveform data from said first memory means or waveform data from said digital adding means to an analog signal in the clock signal cycle corresponding to the data interpolation ratio;

first filter means for removing an aliasing noise from the analog signal output from said digital-to-analog conversion means when the analog signal is based on the data of the first data interpolation ratio;

second filter means for removing an aliasing noise from the analog signal output from said digital-to-analog conversion means when the analog signal is based on the data of the second data interpolation ratio; and

selector switch means for selectively outputting either a signal from said first filter means or a signal from said second filter means.

6. A waveform generator for quadrature modulation operable in accordance with a plurality of band limitation characteristics, comprising:

serial-to-parallel conversion means for converting serial transmission data to parallel data;

mapping means for converting parallel data from said serial-to-parallel conversion means to amplitude phase information and outputting the information as I-channel symbol data and Q-channel symbol data;

first waveform generating means for generating a waveform signal band-limited using a first band limitation characteristic in accordance with I-channel symbol data from said mapping means;

first memory means for storing in advance a difference signal between a waveform signal band-limited using the first band limitation characteristic for said I-channel symbol data and a waveform signal band-limited using a second band limitation characteristic for said symbol data and outputting said difference signal in accordance with said symbol data;

first adding means for adding a waveform signal from said first waveform generating means to a difference signal from said first memory means and outputting the waveform signal band-limited using the second band limitation characteristic;

first selector switch means for selectively outputting either a waveform signal from said first waveform generating means or a waveform signal from said first adding means;

second waveform generating means for generating a waveform signal band-limited using a first band limitation characteristic in accordance with I-channel symbol data from said mapping means;

second memory means for storing in advance a difference signal between a waveform signal band-limited using the first band limitation characteristic for said Q-channel symbol data and a waveform signal band-limited using a second band limitation characteristic for said symbol data and outputting said difference signal in accordance with said symbol data;

second adding means for adding a waveform signal from said second waveform generating means to a difference signal from said second memory means and outputting the waveform signal band-limited using the second band limitation characteristic; and

second selector switch means for selectively outputting either a waveform signal from said second waveform generating means or a waveform signal from said second adding means.