JP2001332985A - Transmission power control circuit and transmitter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control transmission power in an antenna terminal into desired value, even when a positive power supply voltage to be supplied to a PA is lowered. SOLUTION: A signal from a PA 10 is coupled by a coupler 60, the power of this signal is detected by a LOG detecting circuit 90, PA voltage data corresponding to the transmission power in the terminal of an antenna 80 are generated, through calculating this transmission power by a PA positive voltage generating circuit 110, on the basis of the detected result, and these data are converted into a positive power supply voltage by a D/A converter 120 and supplied to the PA 10. Also correction gain data corresponding to the PA voltage data from the PA positive voltage generating circuit 110 are generated by an AGC voltage correcting circuit 130, these correction gain data and control voltage data from a BB circuit 10 are added by a voltage adder circuit 140, and the added result is converted to a control voltage by a D/A converter 150 and supplied to an AGC amplifier 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission power control circuit and a transmitter using the same and, more particularly, to a CDMA (Code Code).
Division Multiple Access) modulation method or WCDM
The present invention relates to a transmitter using an A (Wide band CDMA) modulation scheme and a transmission power control circuit used for the transmitter.

[0002]

2. Description of the Related Art Conventional CDMA modulation method or WCDM
In a transmitter using the A modulation method, a transmission power control circuit including a PA (power amplifier) for amplifying a predetermined signal is provided, and a signal amplified by the PA is radiated through an antenna. Is done.

In the above-described transmitter, the distribution of the transmission power at the antenna end is a binomial distribution, and the transmission power at the antenna end at the time of medium output or low output is determined.
By increasing the efficiency, the battery time of the device can be improved.

Further, a positive power supply voltage is supplied to the PA, and when the transmission power at the antenna end is low, the power supply voltage supplied to the PA is reduced to reduce the PA.
It is known that efficiency can be improved.

[0005]

In the transmitter as described above, the PA efficiency is improved by lowering the positive power supply voltage supplied to the PA, but the PA gain is reduced. There is a problem that the transmission power at the antenna end becomes lower than a desired value.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. Even when the positive power supply voltage supplied to the PA is reduced, the transmission power at the antenna end can be reduced to a desired level. It is an object of the present invention to provide a transmission power control circuit that can be controlled to a value and a transmitter using the same.

[0007]

According to the present invention, there is provided a baseband circuit for outputting an I signal and a Q signal, and a method for modulating the I signal and the Q signal output from the baseband circuit. A quadrature modulator for outputting, an AGC amplifier for amplifying a signal output from the quadrature modulator by a predetermined gain and outputting the same, and an RF for converting a signal output from the AGC amplifier to a predetermined RF frequency and outputting the same. A power amplifier for amplifying a signal output from the RF circuit by a predetermined gain and outputting the amplified signal, and a coupler and a band-pass filter for passing the signal output from the power amplifier. In a transmission power control circuit for controlling transmission power in an antenna that radiates a signal passed through a pass filter as a radio wave, the coupler includes: A LOG detection circuit that performs coupling processing on the signal output from the amplifier to output the coupling signal as a coupling signal, detects the power of the coupling signal output from the coupler, converts the power value into a voltage value, and outputs the voltage value. A / A that converts a voltage value output from the LOG detection circuit into a digital signal and outputs the digital signal as transmission power data
A D converter and PA positive voltage generation for calculating transmission power at the antenna end based on transmission power data output from the A / D converter, generating PA voltage data corresponding to the transmission power, and outputting the PA voltage data A first D / A converter that converts the PA voltage data output from the PA positive voltage generation circuit into an analog signal and supplies the analog signal as a positive power supply voltage to the power amplifier. Wherein the power amplifier amplifies the signal output from the RF circuit by a gain corresponding to a power supply voltage supplied from the first D / A converter, and outputs the amplified signal.

The PA positive voltage generation circuit calculates an offset based on a coupling loss in the coupler, a pass loss in the coupler, and a pass loss in the bandpass filter, and calculates the offset by the A / D converter. The transmission power at the antenna end is calculated by adding the transmission power to the transmission power data output from the antenna.

The PA positive voltage generation circuit stores in advance a table of a positive power supply voltage supplied to the power amplifier with respect to a transmission power at the antenna terminal, and based on the table, a transmission power at the antenna terminal. Generating the PA voltage data corresponding to.

[0010] The baseband circuit may include the AG
The control voltage data for controlling the gain in the C amplifier is output, and the P voltage output from the PA positive voltage generation circuit is output.
AGC voltage correction circuit for generating and outputting transmission power correction gain data corresponding to A voltage data; control voltage data output from the baseband circuit; and transmission power correction gain data output from the AGC voltage correction circuit. And a voltage addition circuit for outputting the result of the addition as AGC voltage data; and an AG output from the voltage addition circuit.
A second D / A converter for converting the C voltage data into an analog signal and supplying the analog signal as a control voltage to the AGC amplifier, wherein the AGC amplifier outputs an output from the quadrature modulator circuit. The signal obtained by the second D /
It is characterized in that it is amplified and output by a gain corresponding to the control voltage supplied from the A converter.

Further, the AGC voltage correction circuit includes
A table of the transmission power correction gain data for the PA voltage data output from the A positive voltage generation circuit is stored in advance, and the transmission power correction gain data corresponding to the PA voltage data is generated based on the table. And

A transmitter having the transmission power control circuit for modulating and radiating a transmission signal by a predetermined modulation method, wherein the predetermined modulation method is a CDMA modulation method. .

A transmitter having the transmission power control circuit for modulating and radiating a transmission signal by a predetermined modulation method, wherein the predetermined modulation method is a WCDMA modulation method. .

(Operation) In the present invention configured as described above, the signal output from the power amplifier is subjected to coupling processing by the coupler, and the coupling signal is applied to the LO signal.
The power is detected by the G detection circuit, and P is detected based on the detection result.
A positive voltage generation circuit calculates transmission power at the antenna end, generates PA voltage data corresponding to the transmission power, and converts the PA voltage data into a positive power supply voltage at the first D / A converter. It is converted and supplied to the power amplifier,
In the power amplifier, the signal output from the RF circuit is amplified by a gain corresponding to the power supply voltage supplied from the first D / A converter and output.

Therefore, even when the transmission power at the antenna end is small, the PA positive voltage generation circuit
By generating PA voltage data that lowers the power supply voltage supplied to the power amplifier, the efficiency of the power amplifier can be improved.

Transmission power correction gain data corresponding to the PA voltage data output from the PA positive voltage generation circuit is generated and output by the AGC voltage correction circuit, and the control voltage data and the AGC output from the baseband circuit are output. The transmission power correction gain data output from the voltage correction circuit is added by the voltage addition circuit, and the addition result is output as AGC voltage data, and the AGC voltage data is output to the second D / A.
The signal is converted into a control voltage by the converter and supplied to the AGC amplifier, and the signal output from the quadrature modulator circuit is amplified by the AGC amplifier by a gain corresponding to the control voltage supplied from the second D / A converter. Therefore, the gain change of the power amplifier caused by the change of the power supply voltage supplied to the power amplifier can be corrected by the gain of the AGC amplifier.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the transmission power control circuit of the present invention. This transmission power control circuit is suitably used for a transmitter using the CDMA modulation method or the WCDMA modulation method.

As shown in FIG. 1, the transmission power control circuit 1 according to the present embodiment comprises a BB (baseband) circuit 10, a quadrature modulator 20, an AGC (Auto Gain Control) amplifier 3
0, an RF circuit 40, a PA (power amplifier) 50,
Coupler 60 and BPF (Band Pass Filter) 70
, LOG detection circuit 90, A / D converter 100, P
A positive voltage generation circuit 110, D / A converter 120, and A
GC voltage correction circuit 130, voltage addition circuit 140, D
/ A converter 150, and the BPF 70 is connected to the antenna 80.

The BB circuit 10 outputs an I signal and a Q signal which are analog modulated signals,
AGC to control the transmission power at the end to a desired value
The control voltage data Vagc for the amplifier 30 is output.

The quadrature modulator 20 modulates the I signal and the Q signal output from the BB circuit 10 and outputs a signal of a desired frequency.

The AGC amplifier 30 amplifies the signal output from the quadrature modulator 20 by a gain corresponding to the control voltage supplied from the D / A converter 150, and outputs the amplified signal.

The RF circuit 40 performs analog processing such as converting a signal output from the AGC amplifier 30 to a desired RF frequency and outputs the signal. For example, a desired signal of the signal output from the AGC amplifier 30 is output. BPFs 41 and 43 for attenuating out-of-band components, a mixer 42 for converting a signal from the BPF 41 to a desired RF frequency, and a BPF 4
And a driver amplifier 44 that amplifies the signal from the third amplifier.

The internal configuration of the RF circuit 40 differs depending on the configuration of the transmitter, such as whether the transmitter incorporating the transmission power control circuit is a superheterodyne system or a direct conversion system.

The PA 50 amplifies the signal output from the RF circuit 40 by a gain corresponding to the positive power supply voltage supplied from the D / A converter 120 and outputs the amplified signal.

As the PA 50, there are a PA requiring only a positive voltage as a power supply voltage to be supplied and a PA requiring both positive and negative voltages, but the positive voltage greatly affects PA efficiency.

The coupler 60 allows the signal output from the PA 50 to pass through to the BPF 70,
0 is attenuated by a predetermined amount to perform a coupling process, and the signal is used as a coupling signal in LOG.
Output to the detection circuit 90.

The BPF 70 attenuates the out-of-band component of the desired signal of the signal that has passed through the coupler 60 and passes the signal.

The antenna 80 radiates a signal passing through the BPF 70 as a radio wave.

The LOG detection circuit 90 performs power detection of the coupling signal output from the coupler 60, converts this power value into a voltage value, and outputs the voltage value.

The A / D converter 100 includes a LOG detection circuit 9
The voltage value output from 0 is converted into a digital signal and output as transmission power data.

The PA positive voltage generation circuit 110 calculates the transmission power at the end of the antenna 80 by adding an offset relating to the loss at the subsequent stage of the PA 50 to the transmission power data output from the A / D converter 100, It generates and outputs PA voltage data corresponding to the transmission power.

The PA positive voltage generation circuit 110 stores in advance a table of the positive power supply voltage to be supplied to the PA 50 with respect to the transmission power at the antenna 80 end, and generates PA voltage data based on the table.

The D / A converter 120 converts the PA voltage data output from the PA positive voltage generation circuit 110 into an analog signal, and converts the analog signal to a positive power supply voltage P
Supply to A50.

The AGC voltage correction circuit 130 previously stores a table of transmission power correction gain data for the PA voltage data output from the PA positive voltage generation circuit 110, and corresponds to the PA voltage data based on the table. Generate and output transmission power correction gain data.

The voltage addition circuit 140 adds the control voltage data Vagc output from the BB circuit 10 and the transmission power correction gain data output from the AGC voltage correction circuit 130, and outputs the addition result as AGC voltage data. I do.

The D / A converter 150 includes a voltage adding circuit 14
0 is converted to an analog signal, and the analog signal is used as a control voltage by the AGC amplifier 3.
Supply for 0.

Hereinafter, the operation of the transmission power control circuit configured as described above will be described with reference to FIG.

When the I signal and the Q signal are output from the BB circuit 10, the I signal and the Q signal are modulated by the quadrature modulator 20, the gain is adjusted by the AGC amplifier 30, and
Each component provided in the RF circuit 40 performs analog processing.

The signal subjected to analog processing in each component provided in the RF circuit 40 is amplified by the PA 50 and then radiated from the antenna 80 via the coupler 60 and the BPF 70.

Here, the CDMA modulation method or the WCDM
In the transmitter using the A-modulation method, as described above, the distribution of the transmission power at the antenna 80 end is a binomial distribution. Consideration must be given not only to the time, but also to medium and low power.

When the transmission power at the end of the antenna 80 is small, the efficiency of the PA 50 is greatly improved by reducing the positive voltage supplied to the PA 50. Therefore, control of the positive voltage supplied to PA 50 with respect to the transmission power at the end of antenna 80 will be considered.

FIG. 2A is a characteristic diagram showing the relationship between the transmission power Pout at the end of the antenna 80 and the positive voltage Vdd supplied to the PA 50. The PA positive voltage generation circuit 11
At 0, the table shown in FIG. 2A is stored in advance as a table of the PA voltage data for the transmission power Pout.

While a signal is radiated via the antenna 80, the signal output from the RF circuit 40 is subjected to coupling processing in the coupler 60 and output as a coupling signal. Thereafter, power detection is performed by the LOG detection circuit 90, the power value is converted to a voltage value and output, and the voltage value is converted to a digital signal by the A / D converter 100 and output.

When the transmission power Pout at the end of the antenna 80 is obtained, first, the data converted into a digital signal by the A / D converter 100 and output is used as transmission power data.

Here, the transmission power data output from the A / D converter 100 indicates the power value of the coupling signal output from the coupler 60, and
It is different from the transmission power at the end.

Therefore, in order to determine the transmission power at the end of the antenna 80, the transmission power data output from the A / D converter 100 is compared with the transmission loss and the coupling loss in the coupler 60 and the transmission loss in the BPF 70. Needs to be taken into account.

That is, an offset is calculated from the equation [coupling loss of coupler 60-passage loss of coupler 60-passage loss of BPF 70: (loss is represented by a positive number)], and this offset is calculated by the A / D converter. The sum of the transmission power data output from the transmission power 100 and the transmission power Pout at the end of the antenna 80 matches the transmission power data.

In the PA positive voltage generation circuit 110, A
The transmission power Pout at the end of the antenna 80 is calculated by adding the offset calculated as described above to the transmission power data output from the / D converter 100,
PA voltage data corresponding to the calculated transmission power Pout is generated and output based on the table shown in FIG.

The PA voltage data output from PA positive voltage generation circuit 110 is converted into an analog signal by D / A converter 120, and this analog signal is converted to a positive voltage Vdd by P
Supplied to A50.

However, when the positive voltage supplied to the PA 50 is reduced, the gain of the PA 50 is also reduced.

FIG. 2B is a characteristic diagram showing the relationship between the positive voltage Vdd supplied to the PA 50 and the gain of the PA 50.

As shown in FIG. 2B, when the positive voltage Vdd supplied to the PA 50 is the reference voltage Vparef, the PA5
When the positive voltage Vdd supplied to the PA 50 is reduced to Vpa2 and Vpa1 with respect to the gain Gparef of 0, the gain of the PA 50 decreases by ΔG2 and ΔG1, respectively.

Therefore, in the AGC voltage correction circuit 130, a change in the positive voltage Vdd supplied to the PA 50
Transmission power correction gain data for canceling the 50 gain change with the gain of the AGC amplifier 30 is generated and output based on a table of transmission power correction gain data for PA voltage data stored in advance.

FIG. 2C is a characteristic diagram showing the relationship between the positive voltage Vdd supplied to the PA 50 and the correction gain that needs to be corrected by the AGC amplifier 30.

As shown in FIG. 2C, for example, PA5
When the positive voltage Vdd supplied to 0 is Vpa2, AG
Since the correction gain corrected by the C amplifier 30 is ΔG2, the transmission power correction gain data corresponding to the correction gain ΔG2 is output from the AGC voltage correction circuit 130.

In the voltage adding circuit 140, the control voltage data Vagc for the AGC amplifier 30 output from the BB circuit 10 and the transmission power correction gain data output from the AGC voltage correction circuit 130 are added. Is output as AGC voltage data.

The control voltage data output from the BB circuit 10 is supplied to the AGC amplifier 30 for controlling the transmission power at the end of the antenna 80 to a desired value when the reference voltage Vparef is supplied to the PA 50. Is the control voltage data.

AGC output from voltage adding circuit 140
The voltage data is converted into an analog signal by the D / A converter 150, and the analog signal is supplied to the AGC amplifier 30 as a control voltage.

FIG. 2D is a characteristic diagram showing the relationship between the transmission power Pout at the end of the antenna 80 and the gain of the AGC amplifier 30.

As described above, in the BB circuit 10, the reference voltage Vparef is supplied to the PA 50, and the PA 50
Assuming that the gain of
Since the control voltage data for controlling the gain of the amplifier 30 is output, if the gain of the AGC amplifier 30 is to be controlled only by the control voltage data output from the BB circuit 10, the gain curve of the AGC amplifier 30 is as shown in FIG. (D)
As shown in the figure, when the transmission power Pout at the end of the antenna 80 is equal to or less than P2, it changes as indicated by the broken line.

However, for example, the transmission power correction gain data corresponding to the correction gain ΔG 2 is output from the AGC voltage correction circuit 130, and the AGC amplifier 30 uses the transmission power correction gain data and the control voltage data output from the BB circuit 10. When the transmission power at the end of the antenna 80 is between P1 and P2, the AGC
The gain of the AGC amplifier 30 is increased by the correction gain ΔG2 according to the transmission power correction gain data output from the voltage correction circuit 130.

Accordingly, the gain reduction of the PA 50 is equal to the AGC
This is corrected by the gain increase of the amplifier 30, whereby desired transmission power is obtained at the end of the antenna 80.

[0064]

As described above, in the present invention,
A LOG detection circuit for power detection of a coupling signal obtained by coupling output from a power amplifier by a coupler; and a transmission power at an antenna end is calculated based on a detection result of the LOG detection circuit, and the transmission power corresponding to the transmission power is calculated. A PA positive voltage generation circuit for generating PA voltage data;
A first D / A which converts the PA voltage data generated by the A positive voltage generation circuit into a positive power supply voltage and supplies the same to the power amplifier.
And a power amplifier, wherein the power amplifier is configured to amplify a signal output from the RF circuit by a gain corresponding to the power supply voltage supplied from the first D / A converter and output the amplified signal. I have.

Therefore, even when the transmission power at the antenna end is small, the PA positive voltage generation circuit
By generating PA voltage data that lowers the power supply voltage supplied to the power amplifier, the efficiency of the power amplifier can be improved.

An AGC voltage correction circuit for generating and outputting transmission power correction gain data corresponding to the PA voltage data output from the PA positive voltage generation circuit, a control voltage data and an AGC voltage output from the baseband circuit A voltage addition circuit that adds the transmission power correction gain data output from the correction circuit and outputs the addition result as AGC voltage data; and an AGC amplifier that converts the AGC voltage data output from the voltage addition circuit to a control voltage and And a second D / A converter that supplies the signal output from the quadrature modulator circuit to the AGC amplifier by a gain corresponding to the control voltage supplied from the second D / A converter. In this configuration, the gain of the power amplifier changes due to the change in the power supply voltage supplied to the power amplifier. It can be corrected by the gain of the AGC amplifier.

For this reason, even when the gain of the power amplifier is reduced by lowering the power supply voltage supplied to the power amplifier for the purpose of improving the power amplifier efficiency when the transmission power at the antenna end is small, this gain is reduced. Can be corrected by the gain of the AGC amplifier,
Thereby, the transmission power at the antenna end can be controlled to a desired value.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a transmission power control circuit according to the present invention.

FIG. 2 is a characteristic diagram for explaining an operation of the transmission power control circuit shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 transmission power control circuit 10 BB circuit (baseband circuit) 20 quadrature modulator 30 AGC amplifier 40 RF circuit 41 BPF 42 mixer 43 BPF 44 driver amplifier 50 PA (power amplifier) 60 coupler 70 BPF 80 antenna 90 LOG detection circuit 100 A / D converter 110 PA positive voltage generation circuit 120 D / A converter 130 AGC voltage correction circuit 140 Voltage addition circuit 150 D / A converter

Claims (7)

[Claims] 1. A baseband circuit for outputting an I signal and a Q signal, a quadrature modulator for modulating and outputting an I signal and a Q signal output from the baseband circuit, and a quadrature modulator output from the quadrature modulator An AGC amplifier that amplifies a signal by a predetermined gain and outputs the signal, an RF circuit that converts a signal output from the AGC amplifier to a predetermined RF frequency and outputs the signal,
A power amplifier that amplifies a signal output from the RF circuit by a predetermined gain and outputs the amplified signal; and a coupler and a bandpass filter that pass the signal output from the power amplifier. In a transmission power control circuit for controlling transmission power in an antenna that radiates a passed signal as a radio wave, the coupler performs a coupling process on a signal output from the power amplifier and outputs the signal as a coupling signal; A LOG detection circuit that detects the power of the coupling signal output from the LOG detection circuit, converts the power value to a voltage value and outputs the voltage value, and converts the voltage value output from the LOG detection circuit to a digital signal to transmit power data. An A / D converter that outputs the data as: and based on the transmission power data output from the A / D converter. Calculating the transmission power at the antenna end, and generating and outputting PA voltage data corresponding to the transmission power.
A positive voltage generation circuit, a first D / D converter that converts PA voltage data output from the PA positive voltage generation circuit into an analog signal, and supplies the analog signal as a positive power supply voltage to the power amplifier.
An A converter, wherein the power amplifier amplifies a signal output from the RF circuit by a gain corresponding to a power supply voltage supplied from the first D / A converter, and outputs the amplified signal. Characteristic transmission power control circuit. 2. The transmission power control circuit according to claim 1, wherein the PA positive voltage generation circuit adjusts an offset based on a coupling loss in the coupler, a transmission loss in the coupler, and a transmission loss in the band-pass filter. A transmission power control circuit that calculates the transmission power at the antenna end by calculating the offset and adding the offset to the transmission power data output from the A / D converter. 3. The transmission power control circuit according to claim 2, wherein the PA positive voltage generation circuit previously stores a table of a positive power supply voltage supplied to the power amplifier with respect to a transmission power at the antenna end. A transmission power control circuit for generating the PA voltage data corresponding to the transmission power at the antenna end based on the table. 4. The transmission power control circuit according to claim 1, wherein the baseband circuit outputs control voltage data for controlling a gain of the AGC amplifier, and An AGC voltage correction circuit that generates and outputs transmission power correction gain data corresponding to the PA voltage data output from the voltage generation circuit; a control voltage data output from the baseband circuit and an output from the AGC voltage correction circuit A transmission power correction gain data, and outputs a result of the addition as AGC voltage data; and converts the AGC voltage data output from the voltage addition circuit into an analog signal, and converts the analog signal into a control voltage. And a second D / A converter that supplies the AGC amplifier to the AGC amplifier. The signal output from the vessel circuit, transmission power control circuit, characterized in that amplifies only the gain corresponding to the supplied control voltage from said second D / A converter. 5. The transmission power control circuit according to claim 4, wherein the AGC voltage correction circuit stores in advance a table of the transmission power correction gain data for the PA voltage data output from the PA positive voltage generation circuit. A transmission power control circuit that generates the transmission power correction gain data corresponding to the PA voltage data based on the table. 6. A transmitter having the transmission power control circuit according to claim 1, wherein the transmitter modulates and radiates a transmission signal using a predetermined modulation method, wherein the predetermined modulation method is used. Is a CDMA modulation system. 7. A transmitter comprising the transmission power control circuit according to claim 1, wherein the transmitter modulates and radiates a transmission signal using a predetermined modulation method, wherein the predetermined modulation method is used. Is a WCDMA modulation system.