JPH02214330A - Digital agc circuit - Google Patents

Abstract

PURPOSE:To miniaturize a circuit scale and simultaneously to compensate a change in an output level due to the temperature characteristic of a conversion section or the like by using an A/D converter and a D/A converter and adding a process amplifier to a device applying digital processing. CONSTITUTION:An A/D converter section 1 converts an analog input signal 10 into a digital signal and outputs an A/D data 11. A processing section 2 is a part applying digital processing to the A/D data 11 and the content of processing by the processing section 2 is optical. The processing section 2 outputs a digital data 12. The D/A converter section 3 receives the digital data 12 and outputs an analog output signal 13. A process amplifier 4 receives an analog output signal 13 and generates a control voltage 14 in response to the level of the analog output signal 13. The A/D converter section 1 uses the control voltage 14 as a reference voltage to apply A/D conversion.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a digital AGC circuit, and in particular, it inputs an analog signal, sets the digitally converted signal to a constant level using a certain reference value, and then converts it to an analog signal and outputs it. The present invention relates to a digital AGC circuit.

[Conventional technology]

In the conventional AGC circuit, an analog AGC circuit is provided at either or both of the A/D converter and the D/A converter.

[Problem to be solved by the invention]

The above-mentioned conventional analog AGC circuit has the disadvantage that the circuit scale becomes large because a circuit separate from the digital processing section must be provided.

Another disadvantage is that the digital circuit has a negative effect on the analog AGC circuit, such as noise.

[Means to solve the problem]

The digital AGC circuit of the present invention converts analog input signals into A
After inputting the signal digitally converted by the /D conversion section and inputting the digitally processed signal in the processing section, the D
A process amplifier that outputs an analog output signal as an analog output signal by an A/A converter, which inputs the analog output signal, generates an AGC control voltage, and supplies the AGC control voltage to the A/D converter. has.

〔Example〕

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.

The A/D converter 1 converts an analog input signal 10 into a digital signal and outputs A/D data 11.

The processing section 2 is a section that performs digital processing on the A/D data 11, and the processing content of the processing section 2 is arbitrary. The processing section 2 outputs digital data 12. D/A converter 3
receives digital data 12 and outputs analog output signal 13
Output. Process amplifier 4 has analog output signal 13
is received, and a control voltage 14 corresponding to the level of the analog output signal 13 is generated. The A/D converter 1 performs A/D conversion using the control voltage 14 as a reference voltage.

Next, the AGC operation of this embodiment will be explained using equations. A/
The relationship between input and output signals of the D converter 1 can be expressed by equation (1).

A/D data = analog input voltage x resolution ÷ reference voltage
...(1) Therefore, the increase or decrease in A/D data is due to the change in the analog input voltage and the change in the reference voltage, which keeps the resolution constant.The analog input signal 10 and the analog output signal 13 can be calculated from equation (1). If the input signal is x and the reference voltage of the A/D converter is y, it can be seen that it is expressed by a certain function F (x, y) with X and y as variables. Therefore, the analog output signal 13
is expressed by equation (2).

Analog output signal = F (x・control voltage)...
Assuming that the input/output relationship of the process amplifier is expressed by a certain function G (x), the control voltage 14 is expressed by equation (3).

Control voltage = G (analog output signal) (3)
From the above equations (2) and (3>), the analog output signal is (4
) is expressed by the formula.

Analog output signal = F (x - G (d analog output signal)
)...(4) From equation (4), it can be seen that the change in the analog output signal is expressed as a function of the analog input signal X and the analog output signal as variables. Therefore, the AGC operation that keeps the analog output signal constant regardless of changes in the analog input signal becomes possible by appropriately selecting the function G(x).

〔Effect of the invention〕

As explained above, according to the present invention, an AGC circuit can be realized by adding a process amplifier to a device that performs digital processing using an A/D converter and a D/A converter. Therefore, compared to the conventional AGC circuit, the circuit scale can be reduced. This circuit also has the effect of being able to compensate for changes in the output level due to temperature characteristics of the A/D conversion section, processing section, and D/A conversion section.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. 1... A/D conversion section, 2... Processing section, 3... D/
A conversion section, 4... Process amplifier, 10... Analog input signal, 11... A/D data, 12... Digital data, 13... Analog output signal, 14...
・Control voltage.

Claims (1)

[Claims] A digital processing device that inputs a signal obtained by converting an analog input signal into a digital signal by an A/D converter, inputs a signal processed digitally by a processor, and then outputs the signal as an analog output signal by a D/A converter, A digital AGC circuit comprising a process amplifier that inputs an output signal to generate an AGC control voltage and supplies the AGC control voltage to the A/D converter.