JPH04344715A - A/d converter - Google Patents

Abstract

PURPOSE:To reduce distortion due to nonlinearity of an input impedance of the A/ D converter. CONSTITUTION:An amplifier 1 amplifies an input analog signal (a) to a prescribed level and outputs it. An A/D converter 2 uses a sampling clock (b) to convert and output the analog signal (a) by using a sampling clock (b) into a digital signal (d). A feedback circuit 7 adjusts the phase and the level of the analog signal C to feed back the result to an input of the amplifier 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog-to-digital converter for converting analog signals into digital signals.

0002

2. Description of the Related Art FIG. 2 is a block diagram of an example of a conventional analog-to-digital converter.

In the conventional example, an amplifier 11 amplifies an analog signal from an input terminal 3 to a predetermined level, and a sampling clock from an input terminal 4 converts the analog signal from the amplifier 11 into a digital signal, which is then sent to an output terminal 5. It is configured to include an analog-to-digital (hereinafter referred to as A-D) conversion circuit 12 that outputs output.

0004

[Problems to be Solved by the Invention] The above-mentioned conventional analog-to-digital converter has the disadvantage that distortion occurs due to the nonlinearity of the input impedance of the A-D conversion circuit that converts an analog signal into a digital signal. Ta.

[0005]

[Means for Solving the Problems] The analog-to-digital converter of the present invention includes an amplifier that amplifies an input first analog signal to a predetermined level and outputs the amplified signal, and a sampling clock to convert the first analog signal into a digital signal. an analog-to-digital conversion circuit for converting and outputting the digital signal; a digital-to-analog conversion circuit for converting and outputting the digital signal into a second analog signal using the sampling clock; and a digital-to-analog conversion circuit for converting and outputting the digital signal into a second analog signal; It has a feedback circuit that provides negative feedback to the input.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention.

This embodiment includes an amplifier 1 that amplifies an analog signal a to a predetermined level and outputs the amplified signal, and a sampling clock b.
An analog-to-digital (A-D) converter circuit 2 converts and outputs an analog signal a to a digital signal d using a sampling clock b, and a digital-to-analog (D-A) converter circuit 6 converts and outputs a digital signal d to an analog signal c using a sampling clock b. and a feedback circuit 7 that adjusts the phase and level of the analog signal C and provides negative feedback to the input of the amplifier 1.

Next, to explain the operation, input terminal 3
The output of an amplifier 1, which amplifies the analog signal a from the amplifier 1 to the required level, is connected to the input of an A/D converter 2. The sampling clock b input from input terminal 4 is A-D.
The signal is supplied to the conversion circuit 2 and the DA conversion circuit 6. A-D
The conversion circuit 2 outputs a digital signal d obtained by converting the analog signal a to an output terminal 5. The DA conversion circuit 6 outputs an analog signal C obtained by converting the digital signal d. The analog signal C is connected to the input of the amplifier 1 through a feedback circuit 7.

[0009] In this way, the A-D conversion circuit 2 and the D
Since the analog signal C from the -A conversion circuit 6 and the feedback circuit 7 is negatively fed back to the amplifier 1, the nonlinearity of the input impedance of the AD conversion circuit 2 can be improved.

0010

As explained above, the present invention converts the converted output digital signal into an analog signal again, and applies negative feedback to the amplifier of the input analog signal. Distortion caused by impedance nonlinearity can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of an example of a conventional analog-to-digital converter.

[Explanation of symbols]

1 Amplifier 2 A-D conversion circuit 3 Analog signal 4 Sampling clock 5 Digital signal 6 DA conversion circuit 7 Feedback circuit

Claims (1)

[Claims] 1. An amplifier that amplifies an input first analog signal to a predetermined level and outputs the amplified signal; an analog-to-digital conversion circuit that converts and outputs the first analog signal into a digital signal using a sampling clock; and a feedback circuit that adjusts the phase and level of the second analog signal and provides negative feedback to the input of the amplifier. Analog-to-digital converter.