JP3083491B2 - Portable communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable communication device, and more particularly, to a portable telephone device or the like which is driven by a stabilized power through a regulator using a battery as a power source, and a digital circuit for transmission at the time of transmission. The present invention relates to a portable communication device capable of preventing malfunction.

[0002]

2. Description of the Related Art In a PHS or a portable telephone device, etc.,
Digital circuits made into ICs are frequently used due to miniaturization, and a power output transmission circuit for wirelessly transmitting predetermined data and voice is built in. In this type of portable communication device, the power supply transmission circuit and the digital value-based signal processing circuit differ in power supply voltage from each other in order to reduce power consumption, and at the time of transmission operation, Because a large amount of power is consumed, a stabilized power supply circuit that operates separately during transmission is provided, and power is supplied to the transmission circuit via this.

[0003] For this reason, in a portable telephone device, usually, a regulator which operates at a transmission time and supplies a power having a predetermined operating voltage to a transmission circuit for power output,
In order to operate a circuit mainly composed of a digital circuit such as an LCD display circuit or a memory, two power supply circuits including a regulator which operates at a relatively low operating voltage and supplies electric power are provided.

FIG. 3 shows an example of a portable telephone device 20 centered on a power supply circuit portion thereof.
An NP-type regulation transistor Tr1, a voltage control circuit 2 connected to the base of the transistor Tr1,
An output voltage detection circuit 3 for sending a detection voltage to be compared to the voltage control circuit 2; and a stabilized power supply circuit for stabilizing the output voltage of the output terminal 4 to a voltage VOL, for example, about 3V. is there. Note that the voltage control circuit 2
It comprises a constant voltage circuit for generating a reference voltage, and an error amplifier circuit for controlling the transistor Tr1 according to the difference between the comparison target voltage and the reference voltage. The output voltage detection circuit 3
Is composed of a series circuit of a resistor R1 and a resistor R2, and divides the voltage VOL of the output terminal 4 by these resistors to generate a detection voltage. Further, c1 is a smoothing capacitor,
The transistor Tr1 has an emitter connected to the power supply line Vcc and a collector connected to the output terminal 4. The output (voltage VOL) of the output terminal 4 of the regulator 1 is supplied to a signal processing circuit 5 mainly composed of a digital circuit, a controller 6,
The power is supplied to the key input circuit 7 and the like.

[0005] Reference numeral 8 denotes a transmission circuit in which DT is provided.
A modulation circuit 8a including a dial transmission circuit such as an MF, for example, a power output circuit 8b connected to an antenna 8c and the like are built in. The power of the transmission circuit 8 is supplied to the regulator 9
And is started in response to a control signal from the controller 6. The regulator 9 includes a PNP-type regulation transistor Tr2, a voltage control circuit 10 connected to the base of the transistor Tr2,
0, an output voltage detection circuit 11 for sending a detection voltage to be compared with the output voltage.
H, for example, a stabilized power supply circuit that stabilizes to about 3.3V. Note that, similarly to the voltage control circuit 2, the voltage control circuit 10 includes a constant voltage circuit for generating a reference voltage and a transistor Tr2 according to a difference between the comparison target voltage and the reference voltage.
And an error amplifier circuit that controls The output voltage detection circuit 11 is formed of a series circuit of a resistor R3 and a resistor R4, and divides the voltage VOH of the output terminal 13 by these resistors to generate a detection voltage. Further, c2 is a smoothing capacitor. The transistor Tr2 has an emitter connected to the power supply line Vcc, and a collector connected to the output terminal 13.
It is connected to the.

Further, the voltage control circuit 10 is connected to the power supply line Vcc via the switch circuit 12, and obtains operating power. The switch circuit 12 is turned ON only when receiving a control signal ST from the controller 6 and performing a transmission operation. As a result, the voltage control circuit 10 operates the internal error amplifier circuit and turns on the transistor Tr2. Therefore, when the switch circuit 12 is not turned on, power consumption by the regulator 9 is almost nil. In this way, power is supplied only at the time of transmission, and unnecessary power consumption is suppressed. The power supply line Vcc is connected to the positive electrode of the battery 14. A power-on switch circuit provided between the battery 14 and the power supply line Vcc is omitted in the figure. The controller 6 generates a control signal ST for turning on the switch circuit 12 when a predetermined input key corresponding to transmission is input from the key input circuit 7.
The signal processing circuit 5 includes a memory, a gate array, a logic circuit, and an LCD (Liquid Crystal Display) inside, and includes a control signal from the controller 6 and key information input from the key input circuit 7. In response thereto, predetermined data display processing or the like is performed in accordance with these, and data for transmission is generated. Note that the signal processing circuit 5 may further include a dial oscillation circuit such as a communication circuit or a dial.

[0007]

In the portable communication device as described above, the power consumption of the transmitting circuit 8 is required because a constant output is required and the transmitting circuit 8 does not always operate. In order to lower the operating voltage, the operating voltage of the circuit related to the regulator 1 which is always in operation is reduced. FIGS. 4A and 4B illustrate generation of noise when the transmission circuit 8 operates in such a portable communication device. FIG.
And the switch circuit 12 is turned on at time t1. (B) is a noise N generated in response to the output voltage VOL of the output terminal 4. (C) shows a noise waveform generated on the common power supply line Vcc at this time.

As shown in these figures, when the switch circuit 12 is turned on at the time of transmission, the switching noise rides on the power supply line Vcc and appears at the output terminal 4. Therefore, as the operating voltage of the signal processing circuit decreases, the switching noise at the start of the operation of the transmission circuit increases accordingly, and the digital circuits operate via the power supply line Vcc via the stabilized power supply circuit. Noise is added, which makes the digital circuit more likely to malfunction. An object of the present invention is to solve such a problem of the related art, and to provide a portable communication device capable of preventing a malfunction of a digital circuit during transmission.

[0009]

A portable communication apparatus according to the present invention that achieves the above object receives power from a battery and adjusts the voltage to a predetermined voltage via a first stabilized power supply circuit. Portable communication device that sends a signal from a battery to a predetermined voltage via a second stabilized power supply circuit that operates at the time of signal transmission and supplies the signal to a transmission circuit. , A rise adjustment circuit is provided for smoothing the rise of the ON operation of the power output transistor of the second stabilized power supply circuit, and the time until the rise is shorter than the timing at which the transmission circuit enters the transmission operation and the first stabilization. The value is set to a value that can suppress noise due to the ON operation of the power output transistor that rides on the output voltage of the power supply circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the ON operation of the power output transistor of the second stabilized power supply circuit for supplying power to the transmission circuit within a range where the transmission operation is not hindered is suppressed, so that the digital operation is suppressed. Switching noise applied to a power supply line of a signal processing circuit mainly composed of a circuit via a first stabilized power supply circuit is suppressed. As a result, the malfunction of the digital circuit can be suppressed or prevented by a simple circuit.

[0011]

1 is a block diagram mainly showing a power supply circuit of a portable telephone device to which a portable communication device according to the present invention is applied, and FIG. 2 is a rise adjustment time of a rise adjustment circuit in FIG. FIG. 5 is an explanatory diagram of waveforms of power supply lines and the like with respect to switching noise during transmission. Note that the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 21 denotes a portable telephone device, in which a rise time adjusting circuit 15 is provided between a base of a transistor Tr2 and an output terminal 13.

The rise time adjusting circuit 15 is a time constant circuit composed of a series circuit of a capacitor C and a resistor R, and smoothes the output voltage waveform by smoothing the drive waveform of the base voltage of the transistor Tr2. That is, as shown in FIG. 2A, the output voltage VOH of the output terminal 13 is reduced by providing the rise time adjustment circuit 15. Time t2 is a start timing at which the transmission circuit 8 actually starts transmission. (B) is the output voltage VOL of the output terminal 4 generated in response thereto, but the noise N indicated by the dotted line hardly occurs due to the regulation of the regulator 1 (see FIG. 4 (b)). And (c)
Indicates a noise waveform generated on the common power supply line Vcc at this time. There is almost no switching noise.

In this case, the adjustment time α (α <t2−t1) until the rise by the rise time adjustment circuit 15 is related to the allowable time (t2−t1) until the transmission circuit 8 starts the transmission operation. That is, normally, the transmission circuit 8 starts a transmission operation of transmitting data in response to a transmission start signal from the controller 6, but it takes some time until the start of the transmission. In a portable telephone device or the like, there is a margin time of about several tens of microseconds from time t1 to t2 at which the actual transmission operation starts. Therefore, the rise adjustment time α is set to 5 μse
Take 10 μsec from c. Therefore, the capacitance of the capacitor C is, for example, about 5600 pF, and the resistance value of the resistor R is about 20Ω.

The rise adjustment time α is determined by the time until the actual start of the transmission operation of the transmission circuit and the amount of noise generated by the power during the operation of the transmission circuit, and is 5 μsec to 10 μsec. It is not limited to the range. In transmission circuits that require large power,
By increasing the rise adjustment time and delaying the start-up timing signal sent from the controller 6 to the transmission circuit 8, noise on the power supply line Vcc can be reduced.

As described above, in this embodiment, a CR time constant circuit is provided between the base of the power output transistor of the stabilized power supply circuit on the transmission circuit side and the output terminal to smooth the rise of the ON operation. Although it is provided, it may be provided on the side of the error amplifier circuit that controls the transistor. Further, in the embodiments, the example of the portable telephone device has been described, but the present invention is of course applicable to portable communication devices having a built-in transmission circuit.

[0016]

As described above, according to the present invention, the rise of the ON operation of the power output transistor of the stabilized power supply circuit for supplying power to the transmission circuit within a range that does not hinder the transmission operation is obviated. By doing so, switching noise applied to the power supply line of the signal processing circuit mainly composed of a digital circuit via the stabilized power supply circuit is suppressed. As a result, malfunction of the digital circuit can be suppressed or prevented with a simple circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram mainly showing a power supply circuit of a portable telephone device according to an embodiment to which the portable communication device of the present invention is applied.

2A and 2B are explanatory diagrams illustrating waveforms of a power supply line and the like with respect to a rise adjustment time of a rise adjustment circuit in FIG. 1 and switching noise during transmission, and FIG.
Is an explanatory diagram of the voltage waveform at the output terminal of the stabilized power supply circuit for transmission, (b) is an explanatory diagram of the voltage waveform at the output terminal of the stabilized power supply circuit of the signal processing circuit that performs digital processing, and (c).
FIG. 4 is an explanatory diagram of a voltage waveform of a power supply line.

FIG. 3 is a block diagram mainly showing a power supply circuit of a conventional portable telephone device.

4A and 4B are explanatory diagrams of switching noise during transmission in the circuit of FIG. 3; FIG. 4A is an explanatory diagram of a voltage waveform at an output terminal of a stabilized power supply circuit for transmission; Is
FIG. 3C is an explanatory diagram of a voltage waveform at an output terminal of a stabilized power supply circuit of a signal processing circuit that performs digital processing, and FIG.

[Explanation of symbols]

1, 9 ... regulator, 2, 10 ... error amplifier circuit, 3,
11: output voltage detection circuit, 4, 13: output terminal, 5: signal processing circuit, 6: controller, 7: key input circuit, 8
... Transmission circuit, 14 ... Battery, 15 ... Rise time adjustment circuit, C, C1, C2 ... Capacitor, R, R1, R2, R3,
R4: resistance, 20, 21: mobile phone device.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-182826 (JP, A) JP-A-5-55938 (JP, A) JP-A-51-116961 (JP, A) JP-A-6-182 4157 (JP, A) Japanese Utility Model Showa 64-25216 (JP, U) Japanese Utility Model Application Hei 5-52912 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/04-7 / 26 G05F 1/00 H02M 3/00

Claims (1)

(57) [Claims] 1. A second power source which receives power from a battery, adjusts the voltage to a predetermined voltage via a first stabilized power supply circuit, sends the adjusted voltage to a signal processing circuit mainly including a digital circuit, and operates at the time of signal transmission. A portable communication device that adjusts power from the battery to a predetermined voltage via a stabilized power supply circuit and supplies the voltage to a transmission circuit, wherein the power output transistor of the second stabilized power supply circuit
A power adjusting transistor provided with a rising adjustment circuit for smoothing the rising of the N operation, wherein the time until the rising is shorter than the timing at which the transmitting circuit enters the transmitting operation and which is on the output voltage of the first stabilized power supply circuit; A portable communication device set to a value that can suppress noise due to the ON operation of the portable communication device.