Amplifiers – With control of power supply or bias voltage – With control of input electrode or gain control electrode bias
Reexamination Certificate
2000-11-13
2001-10-16
Pascal, Robert (Department: 2817)
Amplifiers
With control of power supply or bias voltage
With control of input electrode or gain control electrode bias
C330S129000, C455S127500, C455S522000
Reexamination Certificate
active
06304139
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmitter adjusting output power, and more particularly to a transmitter which, driven by a battery as in the handset of a mobile telephone, adjusts output power so as to minimize the exhaustion of the power source battery when adjusting the output power of transmit signals.
2. Description of the Related Art
Usually, a cordless mobile telephone, when communicating with another mobile telephone, is subject to fluctuations in the field intensity of the receive wave reaching each mobile telephone depending on the distance between the calling party's mobile telephone and the corresponding telephone relaying base and the state of the wave transmission in-between, as well as the distance between the other party's mobile telephone and the corresponding telephone relaying base and the state of the wave transmission in-between.
If the field intensity of the receive wave reaching the calling party's mobile telephone is weak, the link with the other party may be so affected by noise and the like that satisfactory communication is difficult or sometimes even impossible. On the other hand, if the field intensity of the receive wave reaching the calling party's mobile telephone is strong, the transmission/reception of the wave may be taking place at a signal level which is higher than the necessary signal level. This is not desirable because the exhaustion of the power source battery of the mobile telephone would correspondingly increase.
For this reason, in order to ensure satisfactory communication between one mobile telephone and the other mobile telephone, and to avoid an unnecessary increase in battery exhaustion, when a wave transmitted from the other mobile telephone is received, the field strength of the receive wave should be detected. If the detected field strength is relatively large, the signal gain of the transmitter should be adjusted according to the relative level of the detected field strength to reduce the level of the transmit signal from the transmitter. If the detected field strength is relatively weak, the signal gain of the transmitter should be adjusted according to the relative level of the detected field strength to enhance the level of the transmit signal from the transmitter. Thus, by adjusting the level of the transmit signal sent from the respective transmitters of two mutually communicating mobile telephones, the field strength of the wave received by each other's mobile telephone can be regulated to a standard level, thereby enabling the two mobile telephones to communicate satisfactorily and prevent both mobile telephones from suffering unnecessary exhaustion of their respective power source batteries.
Know adjusting means for signal gains of transmitters in mobile telephone include a first gain adjusting means which fixes the signal gain in the power amplifying stage and makes controllable the signal gain in the drive amplifying stage with a gain control voltage to adjust the level of the transmit signal as required; and also known is a second gain adjusting means which fixes the signal gain in the drive amplifying stage and makes controllable the signal gain in the power amplifying stage with a gain control voltage to adjust the level of the transmit signal as required.
FIG. 3
is a block diagram illustrating the configuration of essential parts of a transmitter using a first gain adjusting means in a known mobile telephone.
As shown in
FIG. 3
, this transmitter is provided with a fixed-gain power amplifying stage (PA)
31
, a variable-gain drive amplifying stage (DA)
32
, a transmit signal generator
33
, a gain control voltage generator
34
, a transmit signal output terminal
35
and a transmit data (TX data) input terminal
36
. Of the transmit signal generator
33
, the input terminal is connected to the transmit data input terminal
36
and the output terminal is connected to the input terminal of the variable-gain drive amplifying stage
32
. Of the variable-gain power amplifying stage
32
, the control terminal is connected to the output terminal of the gain control voltage generator
34
and the output terminal is connected to the input terminal of the fixed-gain power amplifying stage
31
. Of the fixed-gain power amplifying stage
31
, the output terminal is connected to the transmit signal output terminal
35
.
In this case, the transmit signal generator
33
forms a carrier frequency, and modulates the formed carrier frequency with transmit data (TX data) supplied to the transmit data input terminal
36
to generate a transmit signal, and the generated transmit signal is supplied to the variable-gain drive amplifying stage
32
that follows. The gain control voltage generator
34
generates a gain control voltage corresponding to the level of the receive signal that has been received (the field strength of the receive wave), and the gain control voltage so obtained is supplied to the variable-gain drive amplifying stage
32
. Further, the transmit signal output terminal
35
is connected to a transmission antenna (not shown in FIG.
3
).
Schematically, the transmitter using the first gain adjusting means having the above-described configuration operates in the following manner.
As the receiver (not shown in
FIG. 3
) of a mobile telephone receives a signal transmitted by the mobile telephone of the other party to the call, the controller (not shown in
FIG. 3
either) detects a receive signal level representing the field strength of the receive wave. If the detected receive signal level is relatively low, the gain control voltage generator
34
generates a gain control signal to increase the signal gain of the variable-gain drive amplifying stage
32
according to the relative level of the receive signal level, and supplies it to the variable-gain drive amplifying stage
32
. If the detected receive signal level is relatively high, the gain control voltage generator
34
generates a gain control signal to reduce the signal gain of the variable-gain drive amplifying stage
32
according to the relative level of the receive signal level, and supplies it to the variable-gain drive amplifying stage
32
. After that, the variable-gain drive amplifying stage
32
amplifies the transmit signal supplied from the transmit signal generator
33
with a signal gain corresponding to the gain control signal, and supplies the amplified signal to the power amplifying stage
31
. The power amplifying stage
31
further amplifies in power the supplied transmit signal, and supplies the amplified transmit signal to the transmission antenna via the transmit signal output terminal
35
to cause it to be transmitted from the transmission antenna. The transmit signal level required then is so controlled as to be raised when the receive signal level is too low and, conversely, to be lowered when the receive signal level is too high.
Hereupon,
FIG. 4
shows the relationship between the transmit signal level (output power) of a transmitter using the first gain adjusting means and the current consumption by the power amplifying stage
31
.
As illustrated in
FIG. 4
, in the transmitter using the first gain adjusting means, when the required transmit signal level is in a high range, the current consumption by the power amplifying stage
31
increases. In this case, if the required transmit signal level is within the range from 3 to 10 dBm, the rate of variation of the current consumption dependent on the variation of the required transmit signal level is relatively mild, remaining between 30 and 40 mA, but if the required transmit signal level exceeds 10 dBm to approach or reach 24 dBm, the rate of variation of the current consumption dependent on the variation of the required transmit signal level increases to an approximate range of 40 mA to 160 mA.
Next,
FIG. 5
is a block diagram of essential parts of a transmitter using a second gain adjusting means in a known mobile telephone.
As illustrated in
FIG. 5
, this transmitter is provided with a variabl
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Choe Henry
Pascal Robert
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