Telecommunications – Transmitter – Power control – power supply – or bias voltage supply
Reexamination Certificate
2001-03-16
2004-08-03
Corsaro, Nick (Department: 2684)
Telecommunications
Transmitter
Power control, power supply, or bias voltage supply
C455S562100
Reexamination Certificate
active
06771941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a base station of a mobile communication network, and more particularly to a transmission power control apparatus of a base station of a mobile communication network.
2. Description of the Background Art
Generally, an up-converter of a transmitter in a base station of a mobile communication network converts an intermediate frequency (IF) signal to a radio frequency (RF) signal and controls the RF signal to have a suitable level of power (strength). For this purpose, the transmitter includes a voltage detecting unit, an automatic gain controller and an attenuator to detect the strength of a signal on the transmission path and generates a control signal to control the gain of the signal.
And, a different voltage detecting unit and a different controller constructed in other circuit board detect the strength of the signal outputted from the up-converter and control the gain of the signal to have the appropriate strength.
FIG. 1
is a schematic block diagram of the transmitter of a base station of a mobile communication network in accordance with a conventional art.
As shown in the drawing, a transmitting apparatus of the mobile communication network in accordance with the conventional art includes an up-converter
101
for converting a received intermediate frequency (IF) signal to an RF signal and controls the gain of the converted RF signal, a high power amplifier (HPA)
14
for amplifying the RF signal outputted from the up-converter
101
to a high power, a coupling unit
102
for receiving the high power RF signal from the HPA
14
, extracting only a required specific frequency band component of the RF signal, and outputting the extracted signal to an antenna and to a voltage detecting unit
103
, the voltage detecting unit
103
for converting the RF signal received from the coupling unit
102
to an IF signal and detecting a voltage level in proportion to the strength of the converted IF signal, and a controlling unit
104
for receiving the detected voltage and outputting a Tx_RF_GAIN signal.
The voltage detecting unit
103
and the controlling unit
104
serve to judge whether the RF signal on the transmission path has the proper strength and monitor it.
The up-converter
101
includes a splitter
2
for splitting an inputted signal to two different paths, fixed attenuators
3
and
21
for attenuating the power (strength) of the received signal; amplifiers
4
and
11
for compensating a loss generated during the process of attenuating a power, SAW filters
5
and
20
for extracting a required signal among signals outputted from the amplifier
4
, a frequency up mixer
8
for converting the IF signal to an RF signal, a local oscillator
6
for generating a single frequency signal and providing it to the frequency up mixer
8
, band pass filters (BPF)
7
and
9
for passing only a specific band signal, a voltage variable attenuator
10
for attenuating the power (strength) of the received signal under the control of the automatic gain controller
27
, a coupler
12
for coupling a received signal to two elements, an isolator
13
for removing a reflection wave causing a transmission distortion, voltage detectors
26
and
28
for detecting a voltage level in proportion to the strength of the inputted signal, and the automatic gain controller
27
for generating a gain control signal for controlling the voltage variable attenuator
10
.
The operation of the transmitter of the mobile communication network base station in accordance with the conventional art constructed as described above will now be explained.
An IF signal
1
inputted to the up-converter
101
is split to two paths by the splitter
2
, and while the IF signal passes the first fixed attenuator
3
, the amplifier
4
and the first SAW filter
5
, a noise is canceled to a degree. And then, the IF signal is converted to an RF signal by the frequency up mixer
8
and the first local oscillator
6
and outputted to the second band pass filter
9
.
As the RF signal passes the second band pass filter
9
, its specific frequency band component is extracted, and the gain of the filtered signal is controlled to be down by the voltage variable attenuator
10
and outputted to the amplifier
11
.
The amplifier
11
amplifies the power-attenuated RF signal to a certain level and outputs it to the isolator
13
, and the isolator
13
removes the reflection wave included in the RF signal to prevent generation of a transmission distortion. The reflection wave-removed RF signal is outputted to the HPA
14
.
The RF signal is amplified by the HPA
14
to have a high power and outputted to the coupling unit
102
, so that an unnecessary frequency component of the RF signal is removed by the front end filter
15
of the coupling unit
102
and outputted back to the antenna, and also coupled by a directional coupler
16
of the coupling unit
102
so as to be outputted to the voltage detecting unit
103
.
In the voltage detecting unit
103
, the RF signal is converted to the IF signal by the second oscillator
18
and the frequency down mixer
17
and outputted to the amplifier
19
. The second local oscillator
18
generates a signal having a single frequency and provides it to the frequency down mixer
17
.
The IF signal is amplified by the amplifier
19
and inputted through the second SAW filter
20
and the second fixed attenuator
21
to the second voltage detector
22
. The second voltage detector
22
detects the voltage of the received IF signal and outputs it to the controlling unit
104
.
In the controlling unit
104
, the voltage level signal (an analog signal) is converted into a digital signal and inputted to the controller
24
. The controller
24
judges whether the RF signal transmitted through the antenna has a proper strength, computes a difference value (&Dgr;) between the voltage detected by the voltage detecting unit
103
and a reference voltage and provides a Tx_RF_GAIN signal corresponding to the difference value (&Dgr;) to the automatic gain controller
27
. The controller
24
holds a Tx_RF_GAIN signal table corresponding to each voltage difference value.
In the up converter
101
, the coupler
12
positioned before the isolator
13
outputs the received RF signal to the first voltage detector
26
. The first voltage detector
26
detects the voltage level of the received RF signal and outputs it to the automatic gain controller
27
. And, the third voltage detector
28
also receives the IF signal split by the splitter
2
, detects the voltage level of the IF signal and outputs it to the automatic gain controller
27
.
Consequently, the automatic gain controller
27
generates the gain control signal by using the voltage inputted from the first voltage detector
26
, the voltage inputted from the third voltage detector
28
and the Tx_RF_GAIN signal inputted from the controlling unit
104
, and controls the whole outputting of the transmitting apparatus by providing the generated gain control signal to the voltage variable attenuator
10
.
That is, the automatic gain controller
27
generates the gain control signal according to the strength of the RF signal provided from the first voltage detector
26
, or generates the gain control signal according to the Tx_RF_GAIN signal provided from the controlling unit
104
, to control the strength of the RF signal transmitted through the transmission antenna.
The conventional transmission power controlling apparatus of the mobile communication network base station, however, has the following problems.
That is, since the voltage detector, the filter, the local oscillator and the frequency mixer are used redundantly, the production cost of the system is increased.
In addition, the path loss and the deviation due to the allowable error of the elements occurring in the circuit itself which monitors and controls the output signal.
Moreover, the gain control signal may be varied depending on what value a system sets as an initial value when the up-converter is manufactured, a
Corsaro Nick
Fleshner & Kim LLP
LG Electronics Inc.
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