Telecommunications – Receiver or analog modulated signal frequency converter – With particular receiver circuit
Reexamination Certificate
1998-09-21
2001-04-24
Hunter, Daniel (Department: 2684)
Telecommunications
Receiver or analog modulated signal frequency converter
With particular receiver circuit
Reexamination Certificate
active
06223024
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reception circuit. More particularly, this invention relates to an intermittent control reception circuit such as a frequency demodulator in which an intermittent control operation is performed for the sake of low consumptive current as objective.
DESCRIPTION OF THE RELATED ART
In recent years, portable terminal equipments such as a portable telephone, a radio selective-calling receiver and so forth whose technology progresses to the direction that it causes the terminal equipment to be miniaturized, and to be lightened in terms of its body, and also causes the terminal equipment to be lessened in terms of its dissipation current. Among them, with respect to miniaturization and lightening thereof, one method is that power-supply battery is miniaturized, while, with respect to decreasing of dissipation current, it becomes general that the intermittent control operation in which it causes receiver-operation to be performed ON/OFF in constant cycle is executed. The intermittent control operation enables shortening of life time accompanied with miniaturization of the power-supply battery to be improved. The remaining amount of the battery is represented by the unit of Ah (Ampere-hour), thus battery life is capable of being calculated by dissipation current in every unit time. Namely, when it causes the receiver to be implemented intermittent control by the time-timing as shown in
FIG. 1A
, average dissipation current which is obtained in such a way that current in every unit time is integrated, is shown as
FIG. 1B
, with the result that when it causes the receiver to be operated at all times regardless of intermittent control, dissipation current increases in quantity exceedingly. Consequently, the battery life is shown in
FIG. 1C
, since the dissipation current in every unit time increases in quantity exceedingly, when there is no intermittent control, the battery life comes to be short. While, dissipation current in every unit time comes to be approximately ½ (inclination being ½) in comparison with no intermittent control, when it causes timing ON/OFF of the receiver to be implemented by intermittent control of 1:1 thereby, the battery life comes to be approximately two times. Thus, the higher the ratio of the intermittent control operation, namely the longer the total time of OFF-state, the more the battery life is lengthened. Further, the case where the intermittent control operation is possible is confined to the case where necessary data is not transmitted at the state of OFF of the receiver. Namely, the transmission data is separated into several groups, and communication system is confined to the case where it is appropriate that it causes data within certain group of the above several groups to be received.
On the other hand, in this kind of portable equipment, the lower the remaining amount of the battery reduction, the less the normal operation as the equipment is performed, therefore, it is necessary to notify degree of consumption of the battery in order to maintain normal operation thereof, thus there is provided configuration notifying lowering of the amount of the battery by alarm or display indication. For instance, in the radio selective-calling receiver, which notifies the timing of battery change by the alarm or the display indication. A low voltage detector is in use for the circuit notifying battery change, in this kind of radio selective-calling receiver, it is called an intermediate frequency amplifier or simply demodulation circuit, being applied to the circuit so called IFIC (Intermediate Frequency Integrated Circuit, or Demodulation Integrated Circuit).
FIG. 2
is a circuit diagram showing a conventional block circuit of IFIC. The IFIC is provided with an amplitude limiter
101
for limiting amplitude level of input signal being subjected to frequency demodulation to prescribed level, a frequency demodulator
102
for demodulating output signals of the amplitude limiter
101
, a low pass filter
103
for filtering low frequency signals from demodulated signals, a switching circuit
106
for switching cut-off frequency of the low pass filter
103
, a data output circuit
104
for performing digital output of the demodulated signal, and a low voltage detector
105
for notifying it when the power source voltage deteriorates. The respective outputs of the low voltage detector
105
and the data output circuit
104
are inputted to the control circuit
107
individually. The control circuit
107
controls an operation which executes signal output and notifying of deterioration of the remaining amount of the battery based on these data output and output of low voltage detection.
Further, for instance, as shown in
FIG. 3A
, the low voltage detector
105
comprises a bias circuit
111
which is followed by voltage of internal battery
110
, a reference voltage circuit
112
maintained to fixed voltage, and a comparator
113
for comparing voltage of the bias circuit
111
and the reference voltage of reference voltage circuit
112
. In this low voltage detector, as shown in
FIG. 3B
, the voltage value of the reference voltage circuit
112
is taken to be V
1
, the remaining amount of the battery deteriorates, thus resulting in lowering of voltage of the bias circuit
111
, when voltage of the bias circuit
111
deteriorates to V
1
, this agrees with threshold value of the comparator
113
so that output of the comparator
113
is inverted. The inversion signal is inputted to the control circuit
107
from the low voltage detector
105
, so that the control circuit
107
generates alarm.
Now, in the IFIC, the operation is implemented in the timing shown in
FIG. 6B
at the data output circuit
104
and the low voltage detector
105
. In the data output circuit
104
, which receives transmission data to output data, supposing necessary transmission data is transmitted at the time t
1
, efficiency is the best, if the timing of ON of the receiver operation is t
1
. However, some prescribed time period is required for operating normally in terms of the receiver, when the receiver changes from OFF to ON. This time period is so called as rise time for the receiver, and also so called as rise time of local oscillator of the receiver. For this reason, it is necessary to turn the receiver ON-state at the time t
0
before the time t
1
corresponding to rise time ts of the local oscillator, in accordance with this operation, the data output circuit
104
starts the operation from the time t
0
. However, the data output circuit
104
is enough to be started in the timing of the time t
1
, even though it causes the data output circuit
104
to be operated at the time of t
0
, the data during ts is unnecessary data, thus unnecessary current is consumed. Consequently, it is desirable that it causes the intermittent control operation in which operation of the data output circuit is stopped to be implemented at least this period. This matter is also applied to the low voltage detector
105
, in the conventional method, the operation of the low voltage detection is always implemented within the operating time of the receiver, however, it is enough that the low voltage detector
105
implements detecting operation of the low voltage at the certain timing of operation time period of the receiver. It is capable of being implemented the intermittent control operation by the low voltage detector
105
similar to the data output circuit
104
.
Thus, it is desirable to implement intermittent control operation of the data output circuit and the low voltage detector. However, it is necessary to provide exclusive terminal for implementing intermittent control operation on the respective circuits, in order to implement intermittent control operation in terms of the circuits practically. However, in LSI which constitutes these circuits size of the package and the number of the terminals are specified, these are incapable of being established voluntarily, therefore it is difficult to materialize increasing of
Hunter Daniel
NEC Corporation
Nguyen Thuan T.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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