JP2710334B2 - Power amplifier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power amplifying device, and more particularly to a power amplifying device having a switch capable of controlling operation and non-operation while an external power supply is connected.

[Conventional technology]

Conventional power amplifying devices have a switch (hereinafter, referred to as a switch) that can control operation and non-operation while an external power supply is connected.
A standby switch) to control a ripple filter and the like.

FIG. 3 is a circuit diagram of a power amplifying device for explaining such a conventional example.

As shown in FIG. 3, the power amplifying device includes a power amplifying circuit 7 connected between the input terminal 2 and the output terminal 3, and a bias circuit 8 for applying a bias to the power amplifying circuit 7.
And a ripple filter 9 connected between the power supply terminal 1 and the ground terminal 4. The standby switch is composed of transistors 12 to 15, resistors 22 and 23, and a control terminal 5. In such a power amplifying device, when a high-level voltage is applied to the control terminal 5, here a voltage sufficient for the NPN transistors 13 and 15 to operate, the NPN transistor 13 draws the base current of the PNP transistor 12, so that Put the PNP transistor 12 into the operating state.
Also, the NPN transistor 15 draws the base current of the NPN transistor 14, so that the NPN transistor 14 becomes inactive, a current is supplied from the PNP transistor 12 to the base of the NPN transistor 11, and the power is supplied to the bias circuit 8 through the NPN transistor 11. Is supplied. As a result, the bias circuit 8 is activated, and a bias is applied to the power amplification circuit 7, so that the power amplification circuit 7 is activated. That is,
This power amplifying device enters an operating state.

On the other hand, a low level voltage, here NPN, is applied to the control terminal 5.
When a voltage low enough to turn off the transistors 13 and 15 is applied, the NPN transistor 13 is turned off and the base current of the PNP transistor 12 is not drawn, so that the PNP transistor 12 is also turned off. Become. Further, since the NPN transistor 15 is also in the non-operation state, a current is supplied to the base of the NPN transistor 14 from the power supply terminal 1 via the resistor 23, and the NPN transistor 14 is set to the operation state. For this reason, the charge stored in the capacitor 31 of the ripple filter 9 is instantaneously discharged, and the NPN transistor 1
The base voltage of 1 drops to low level. Therefore, no power is supplied to the bias circuit 8 and no bias is supplied to the power amplification circuit 7, so that the power amplification circuit 7 is in a non-operation state. That is, this power amplifying device becomes inactive.

As described above, the standby switch of the conventional power amplifier controls the operation and non-operation of the ripple filter and the operation and non-operation of the discharge circuit of the ripple filter capacitor by one switch function.

[Problems to be solved by the invention]

Since the standby switch of the above-described conventional power amplifying device controls the operation / non-operation of the ripple filter and the operation / non-operation of the capacitor discharge circuit of the ripple filter by one switch function, the ripple switch is used for the ripple filter. The discharging circuit of the formed capacitor will continue to operate even after the capacitor of the ripple filter is discharged, and the current will continue to flow from the power supply terminal.

However, originally, when the power amplifying device is in a non-operation state, the power supplied from the external power source needs to be 0 (zero). This is the same for the power amplifying device which is not operated by the standby switch.

However, such a conventional power amplifying apparatus has a drawback that when it is inactivated by a standby switch, power is supplied from an external power supply.

An object of the present invention is to provide a power amplifying device that makes the power supplied from an external power supply zero when in such a non-operating state.

[Means for Solving the Problems] A power amplifying device according to the present invention includes a power amplifying circuit connected between input and output terminals, a bias circuit for supplying a bias to the power amplifying circuit, and a power supply between the bias circuit and a power supply terminal. And a ripple filter connected to the ripple filter, wherein the ripple filter includes a first switch for controlling the operation and non-operation of the ripple filter, a capacitor discharge circuit of the ripple filter, and a capacitor of the ripple filter. A second switch for controlling the operation and non-operation of the discharge circuit is added.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a power amplifying device for explaining one embodiment of the present invention.

As shown in FIG. 1, the power amplifying device according to the present embodiment includes a power amplifying circuit 7 connected between the input terminal 2 and the output terminal 3, and a bias circuit 8 for biasing the power amplifying circuit 7. And a ripple filter 9 connected between the power supply terminal 1 and the ground terminal 4. The standby switch includes transistors 11 to 16, resistors 22 to 24, a first control terminal 5, and a second control terminal 6. It is composed of

In such a power amplifying device, a high-level voltage is applied to the first control terminal 5, here, a voltage sufficient to operate the NPN transistor 13, and a low-level voltage, here, NPN transistor is applied to the second control terminal 6. When a voltage causing the transistor 15 to be in a non-operating state is applied, the NPN transistor 13 is in an operating state, so that a current is supplied from the PNP transistor 12 to the base of the NPN transistor 11 via the resistor 21. At this time, the NPN transistor 15 is in the non-operation state, so that the PNP transistor 16 is also in the non-operation state. Since no current is supplied from anywhere, the NPN transistor 14 is also in the non-operation state. Here, when the NPN transistor 11 operates, power is supplied to the bias circuit 8 and a bias is supplied from the bias circuit 8 to the power amplifier circuit 7, so that the power amplifier circuit 7 is in an operating state. Therefore, this power amplifying device is in an operating state.

Next, FIG. 2 is a circuit diagram of the power amplifier for explaining the operation of the power amplifier in FIG.

As shown in FIG. 2, in this timing chart, (a) is the supply voltage of the first control terminal 5, (b) is the supply voltage of the second control terminal 6, and (c) is the base voltage of the transistor 11. , (D) represent the current flowing through the power supply terminal 1, respectively.

First, at a timing, a low-level voltage (voltage at which the NPN transistor 13 becomes inactive) is applied to the first control terminal 5 as shown in (a) and a high-level voltage is applied to the second control terminal 6 as shown in (b). When (a voltage at which the NPN transistor 15 is turned on) is applied, both the NPN transistor 13 and the PNP transistor 12 are turned off, so that no current is supplied to the base of the NPN transistor 11. At the same time, the NPN transistor 15 is activated, so that a current is supplied from the PNP transistor 16 to the base of the NPN transistor 14 via the resistor 23 to operate the NPN transistor 14. As a result, the capacitor 31 is discharged, so that the base of the NPN transistor 11 falls to a low level as shown in FIG. Therefore, since the bias circuit 8 becomes inactive, the power amplifier circuit 7 becomes inactive. In this state, since the NPN transistor 14 continues to operate, a current flows from the power supply terminal 1 as shown in FIG.

Next, at the timing, the voltage of the second control terminal 6 is changed to the low level (NPN transistor 1) as shown in FIG.
5 is the voltage at which non-operating state)
15 is switched to a non-operation state, and no current is supplied from the PNP transistor 16, so that the power supply terminal 1
The current flowing through becomes zero. That is, even when the power amplifying device is set in the non-operation state by the standby switch, the power supplied from the external power supply becomes zero.

[Effects of the Invention] As described above, in the power amplifying apparatus of the present invention, the ripple filter includes a control switch for controlling the operation / non-operation of the ripple filter, a capacitor discharge circuit of the ripple filter, and a capacitor discharge circuit of the ripple filter. By providing the control switch for controlling the operation / non-operation of the power amplifier, there is an effect that the power supplied from the external power supply can be reduced to zero when the power amplifier is set in the non-operation state by the standby switch.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a power amplifying device for explaining one embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of the power amplifying device in FIG. 1, and FIG. FIG. 3 is a circuit diagram of a power amplifying device for explaining the following. 1 ... power terminal, 2 ... input terminal, 3 ... output terminal, 4
... Ground terminal, 5 first control terminal, 6 second control terminal, 7 power amplifier circuit, 8 bias circuit, 9
…… Ripple filter, 11,13,14,15 …… NPN transistor, 12,16 …… PNP transistor, 21-24 …… Resistance, 31…
... capacitors.

Claims (1)

(57) [Claims] A power amplifier connected between an input / output terminal, a bias circuit for supplying a bias to the power amplifier, and a ripple filter connected between the bias circuit and a power supply terminal; In the ripple filter, a first switch for controlling the operation and non-operation of the ripple filter, a capacitor discharge circuit of the ripple filter, and a second switch for controlling the operation and non-operation of the capacitor discharge circuit of the ripple filter A power amplifying device characterized by adding a switch of (1).