JPH08102682A - Apc circuit - Google Patents

Abstract

PURPOSE: To obtain an APC circuit capable of reducing circuit space and power consumption by executing arithmetic processing for a reference signal and radio wave voltage by the use of digital values. CONSTITUTION: The output signal level from an RF amplifier circuit 2 for amplifying an RF signal passed through a variable gain amplifier 1 is detected by a detecting circuit 3 and the digital value of the detected voltage and the digital value of a reference signal to be a digital signal are arithmetically processed by an arithmetic processing circuit 7 and obtained APC voltage is fed back to the amplifier 1 to control its gain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an APC (Automatic Power Control) of an RF signal amplifier used in a mobile phone or the like.
It is about circuits.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration example of a conventional APC circuit, in which 1 is a variable gain amplifier, 2 is an RF amplification circuit, 3 is a detection circuit for detecting the output signal level of the RF amplification circuit 2,
Reference numeral 4 is a D / A converter for converting a reference signal which is a digital signal into an analog signal, and 5 is an input signal of the output signals of the detection circuit 3 and the D / A converter 4, and outputs a value obtained by amplifying the difference. It is an arithmetic processing circuit that does. Note that T ₁ is RF
A signal input terminal, T ₂ is a reference signal input terminal.

Next, the operation will be described. First, the RF signal input from the RF signal input terminal T ₁ passes through the variable gain amplifier 1 and the RF amplification circuit 2, and a part of the output signal thereof is input to the detection circuit 3 to detect the signal level thereof and the detected voltage. Is taken into the arithmetic processing circuit 5. On the other hand, the reference signal input from the reference signal input terminal T ₂ and converted into an analog signal by the D / A converter 4 is also input to the arithmetic processing circuit 5, and the reference signal and the detected voltage are compared. The difference is amplified and output as an APC voltage. The gain is controlled by feeding back the APC voltage to the control terminal of the variable gain amplifier 1. With the above feedback loop, the output signal level of the RF amplifier circuit 2 is accurately maintained at the specified value.

[0004]

However, this A
Since the PC circuit performs arithmetic processing with an analog signal, an analog circuit of a certain size is required, which causes a problem of hindering downsizing of equipment using the APC circuit. Also, the detection voltage of the detection circuit for generating the APC signal is 0V.
There is also a problem that a negative voltage is required as a power source of the arithmetic processing circuit because the voltage value may be a voltage value in the vicinity, and power consumption increases correspondingly.

The present invention solves such conventional problems, and an object thereof is to provide an APC circuit which contributes to downsizing of a circuit space and reduction of power consumption.

[0006]

According to the present invention, an A / D converter is provided at the output of a detection circuit, a reference signal and a detection voltage are arithmetically processed by digital values, and the APC voltage which is the arithmetic result is D / D. The feedback is made to the variable gain amplifier via the A converter.

[0007]

With the above construction, since the reference signal and the detected voltage are processed by digital values, the circuit space is reduced and the power consumption is reduced.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. The same parts as those of the conventional circuit are designated by the same reference numerals. FIG. 1 is a circuit configuration diagram showing an embodiment of an APC circuit of the present invention, in which 1 is a variable gain amplifier whose gain can be varied by the APC voltage, and 2 is an RF which amplifies the output signal of the variable gain amplifier 1. An amplifier circuit 3, a detection circuit for detecting the output signal level of the RF amplification circuit 2, 6 is an A / D converter for converting the detection voltage detected by the detection circuit 3 into a digital value,
Reference numeral 7 is an arithmetic processing circuit that takes in a reference signal and the output of the A / D converter 6 to perform arithmetic processing, and 8 is a D / A converter that converts the output of the arithmetic processing circuit 7 into an analog signal. Note that T ₁ is an RF signal input terminal and T ₃ is a reference signal input terminal.

Next, the operation will be described. First, the RF signal input from the RF signal input terminal T ₁ passes through the variable gain amplifier 1 and the RF amplification circuit 2, and a part of the output signal is input to the detection circuit 3 whose signal level is detected and its detection voltage. Is immediately converted into a digital value by the A / D converter 6. The detection voltage converted into the digital value and the reference signal which is originally a digital signal input from the reference signal input terminal T ₃ are taken into the arithmetic processing circuit 7 and are arithmetically processed as the digital value. The result of the arithmetic processing is
It is converted into an analog signal by the D / A converter 8 and fed back to the variable gain amplifier 1 as an APC voltage to control its gain.

As described above, by performing the arithmetic processing with a digital value, the arithmetic processing circuit 7 can be integrated with, for example, another digital control circuit IC, and the circuit can be easily highly integrated. Further, since the arithmetic processing circuit 7 does not need a negative power source, it can contribute to lower power consumption.

[0011]

As is apparent from the above embodiments, the present invention makes it possible to integrate an arithmetic processing circuit with, for example, another digital control circuit IC by performing arithmetic processing with a digital value, and the circuit is highly integrated. Since it becomes easier, the circuit space can be downsized, and the need for a negative power supply in the arithmetic processing circuit is eliminated, which can contribute to lower power consumption.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of an APC circuit of the present invention.

FIG. 2 is a circuit configuration diagram showing an example of a conventional APC circuit.

[Explanation of symbols]

1 ... variable gain amplifier, 2 ... RF amplifier, 3 ... detector, 4, 8 ... D / A converter, 5,7 ... processing circuit, 6 ... A / D converter, T ₁ ... RF signal input terminal ,
T ₂ , T ₃ ... Reference signal input terminals.

Claims (1)

[Claims] 1. A variable gain amplifier which receives an RF signal as an input and whose gain is controlled by a control voltage, an RF amplifier circuit which amplifies an output signal of the variable gain amplifier and outputs an RF signal, and an output of the RF amplifier circuit. A detection circuit for detecting a signal level, an A / D converter for A / D converting an output voltage of the detection circuit at a specific timing, an output signal of the A / D converter and a reference signal are inputted and arithmetically processed. The D / A converter includes an arithmetic processing circuit and a D / A converter for D / A converting an APC voltage obtained as an output of the arithmetic processing circuit.
An APC circuit which feeds back an APC voltage output from a converter to the variable gain amplifier.