Receiver and method for generating a control signal

• US 7,231,006 B2
• Filed: 06/17/2003
• Issued: 06/12/2007
• Est. Priority Date: 06/18/2002
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Yamauchi, Shigeki
• Primary Examiner(s): Bayard; Emmanuel
• Application Number:
  US10/462,617
• Publication Number:
  US 20030232608A1
• Time in Patent Office: 1,456 Days
• Field of Search: 375/324, 375/326, 375/327, 375/344, 375/345, 455/232.1, 455/234.1, 455/234.2, 455/355
• US Class Current: 375/345
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence

Abstract

A receiver includes an amplifier which is responsive to a control signal to amplify an input signal and which outputs a corresponding amplified signal, a demodulator which demodulates the amplified signal to generate first and second components, a converter which generates first samples corresponding to the respective first and second components and which digitalizes the first sample, and an auto gain controller (AGC) which generates second samples corresponding to the digitalized first samples and which generates the control signal corresponding to the second samples.

Claims

1. A receiver, comprising:

an amplifier which is responsive to a control signal to amplify an input signal, and which outputs a corresponding amplified signal;

a demodulator, coupled with the amplifier, which demodulates the amplified signal to generate first and second components;

a converter, coupled with the demodulator, which generates first samples corresponding to the respective first and second components, and which digitalizes the first samples; and

an auto gain controller (AGC), coupled with the converter, which generates second samples corresponding to the digitalized first samples, and which generates the control signal responsive to the second samples,

wherein said AGC comprises

a digital filter which passes a predetermined signal component of the digitalized first samples to generate the second samples, and

an AGC functional circuit which determines a power of the second samples, compares the power to a threshold level, and generates the control signal responsive to the comparison.

2. The receiver according to claim 1, wherein said AGC functional circuit determines the power of the second samples in accordance with the following equation:

Σ

(I²+Q²)^1/2,

wherein I is a first component in the second samples, and Q is a second component in the second samples.

3. The receiver according to claim 1, wherein said converter comprises:

a direct-current amplifier which amplifies the first and second components;

an analog filter which removes noise in the amplified first and second components to generate the first samples; and

an analog-to-digital converter (ADC) which converts the first samples from analog to digital to provide the digitalized first samples.

4. The receiver according to claim 1, wherein said converter is a first converter, and wherein the input signal is generated by a second converter, the second converter comprising:

a mixer which converts a frequency of a received signal from a radio frequency to an intermediate frequency; and

a saw filter which removes a noise in the converted received signal of the intermediate frequency to generate the input signal.

5. A receiver comprising:

an amplifier which is responsive to a control signal to amplify an input signal, and which outputs a corresponding amplified signal;

a demodulator, coupled with the amplifier, which demodulates the amplified signal to generate first and second components;

a converter, coupled with the demodulator, which generates first samples corresponding to the respective first and second components, and which digitalizes the first samples; and

an auto gain controller (AGC), coupled with the converter, which generates second samples corresponding to the digitalized first samples, and which generates the control signal responsive to the second samples,

wherein said AGC comprises

a digital filter which removes a noise in the digitalized first samples to generate the second samples,

a first AGC functional circuit which generates a first power of the second samples,

a second AGC functional circuit which generates a second power of the digitalized first samples, and

an AGC decision circuit which generates the control signal corresponding to the first and second powers.

6. The receiver according to claim 5, wherein said AGC decision circuit comprises:

a subtraction circuit which subtracts the first power from the second power to generate a third power;

a first comparator which compares the third power and a first threshold value to generate a comparison result;

an adder which adds the comparison result and the first power to generate an addition result; and

a second comparator which compares the addition result and a second threshold value to generate the control signal.

7. The receiver according to claim 5, wherein said AGC decision circuit comprises:

a subtraction circuit which subtracts the first power from the second power to generate a third power;

an adder which adds the third power and the first power to generate an addition result; and

a comparator which compares the addition result and a threshold value to generate the control signal.

8. A receiver comprising:

an amplifier which is responsive to a control signal to amplify an input signal, and which outputs a corresponding amplified signal;

a demodulator, coupled with the amplifier, which demodulates the amplified signal to generate first and second components;

a converter, coupled with the demodulator, which generates first samples corresponding to the respective first and second components, and which digitalizes the first samples; and

an auto gain controller (AGC), coupled with the converter, which generates second samples corresponding to the digitalized first samples, and which generates the control signal responsive to the second samples,

wherein said AGC comprises

a digital filter which removes a noise in the digitalized first samples to generate the second samples,

a first AGC functional circuit which generates a first power of the second samples,

a second AGC functional circuit which generates a second power of the digitalized first samples,

a first equation circuit which calculates an average of the first power to generate a first control pulse,

a second equation circuit which calculates an average of the second power to generate a second control pulse, and

an AGC decision circuit which generates the control signal synchronized with the first and second pulses.

9. A receiver comprising:

an amplifier which is responsive to a control signal to amplify an input signal, and which outputs a corresponding amplified signal;

a demodulator, coupled with the amplifier, which demodulates the amplified signal to generate first and second components;

a converter, coupled with the demodulator, which generates first samples corresponding to the respective first and second components, and which digitalizes the first samples; and

an auto gain controller (AGC), coupled with the converter, which generates second samples corresponding to the digitalized first samples, and which generates the control signal responsive to the second samples,

wherein said converter comprises

a direct-current amplifier which amplifies the first and second components,

an analog filter which removes noise in the amplified first and second components to generate the first samples, and

an analog-to-digital converter (ADC) which converts the first samples from analog to digital,

wherein said control signal is a first control signal, and wherein said AGC comprises

a digital filter which removes a noise in the digitalized first samples to generate the second samples,

a first AGC functional circuit which generates a first power of the second samples,

a second AGC functional circuit which generates a second power of the digitalized first samples,

an AGC decision circuit which generates the first control signal and a second control signal synchronized with the first and second powers, and

a controller which generates a third control signal responsive to the second control signal for controlling the direct-current amplifier.

10. The receiver according to claim 9, wherein the second control signal comprises an enable signal and a switch signal, and wherein said AGC decision circuit comprises:

a comparator which compares the first power and a first threshold value to generate the first control signal;

a subtraction circuit which subtracts the first power from the second power to generate a third power;

an enable signal generator which generates the enable signal according to a comparison result between the third power and a second threshold value; and

a switch signal generator which generates the switch signal according to a comparison result between the third power and a third threshold value.

11. The receiver according to claim 10, wherein said enable signal generator generates the enable signal for enabling a switching of an attenuation amount of the direct-current amplifier when the third power substantially equals the second threshold value, and

wherein said switch signal generator generates the switch signal for selecting the attenuation amount of the direct-current amplifier when the enable signal is generated.

12. The receiver according to claim 11, wherein said switch signal generator generates the switch signal for selecting a first attenuation amount when the third power is less than the third threshold value and for selecting a second attenuation amount when the third power is greater than the third threshold value, wherein the first attenuation amount is less than the second attenuation amount.

13. A receiver, comprising:

a demodulator which demodulates an input signal to generate first and second components;

a variable resister, coupled with the demodulator, which attenuates the first and second components responsive to first and second control signals;

a converter, coupled with the variable resister, which generates first samples corresponding to the attenuated first and second components; and

an auto gain controller (AGC), coupled with the converter, which generates second samples corresponding to the first samples, which generates the first control signal and a carry signal according to at least one peak value of the second samples, and which generates the second control signal according to the carry signal.

14. The receiver according to claim 13, wherein said AGC comprises:

an analog filter which removes a noise in the first samples to generate the second samples;

a comparator which generates the first control signal and the carry signal according to a comparison of a threshold value and the at least one peak value of the second samples; and

an enable signal generator which generates the second control signal according to the carry signal.

15. The receiver according to claim 14, wherein said comparator generates the first control signal for instructing a first attenuation amount when the at least one peak value is less than the threshold value and for instructing a second attenuation amount when the at least one peak value is greater than the threshold value.

16. A receiver comprising:

a demodulator which demodulates an input signal to generate first and second components;

a variable resister, coupled with the demodulator, which attenuates the first and second components responsive to first and second control signals;

a converter, coupled with the variable resister, which generates first samples corresponding to the attenuated first and second components; and

an auto gain controller (AGC), coupled with the converter, which generates second samples corresponding to the first samples, which generates the first control signal and a carry signal according to at least one peak value of the second samples, and which generates the second control signal according to the carry signal,

wherein said AGC comprises

an analog filter which removes a noise in the first samples to generate the second samples,

an adjuster circuit which adjusts an amplitude and phase of the first samples to the generate adjusted first samples,

a differential amplifier which generates a difference between the second samples and the adjusted first samples to determine a noise amount,

a comparator which generates the first control signal and the carry signal according to a comparison of a threshold value and a peak value of the noise amount, and

an enable signal generator which generates the second control signal according to the carry signal.

17. A receiver, comprising:

a demodulator which demodulates an input signal to generate first and second components;

a variable resister, coupled with the demodulator, which attenuates the first and second components responsive to first and second control signals;

a direct-current amplifier, coupled with the variable resister, which amplifies the attenuated first and second components; and

an auto gain controller (AGC), coupled with the direct-current amplifier, which generates at least one peak value of the amplified first and second components, which generates the first control signal and a carrier signal responsive to the peak value and a threshold value, and which generates the second control signal corresponding to the carrier signal.

18. A method for generating a control signal, comprising:

amplifying an input signal according to a control signal;

demodulating an amplified signal to generate first and second components;

generating first samples corresponding to the respective first and second components;

digitalizing the first samples;

generating second samples corresponding to the digitalized first samples; and

generating the control signal responsive to the second samples,

wherein said generating second samples comprises inputting the digitalized first samples through a digital filter that passes a predetermined signal component of the digitalized first samples as the second samples, and

wherein said generating the control signal comprises determining a power of the second samples, comparing the power to a threshold level, and generating the control signal responsive to the comparison.