JP3258902B2 - Hybrid integrated circuit 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 hybrid integrated circuit device, and more particularly, to a hybrid integrated circuit device having a switching power supply circuit and an amplifier circuit for use in a vehicle-mounted audio amplifier or the like.

[0002]

2. Description of the Related Art A circuit configuration of a vehicle-mounted audio amplifier according to a conventional example will be described below. This circuit is shown in FIG.
A circuit as shown in FIG.
4), the switching power supply circuit (10)
1) and its two voltage output terminals (104), (10)
5) has two voltage input terminals (10
6), the amplifier circuit (10) applied through (107)
2) etc. The output signal of the amplifier circuit (102) is supplied to a speaker (103) and the like.

Further, a switching power supply circuit (101) outputs a signal for operating or stopping a switch element (123) in a chopper circuit (113).
14). By this comparison circuit (114),
Amplifying circuit (10) according to the magnitude of the amplified signal (ZS)
The power supply voltage (± Vc) to be supplied to 2) is switched to improve the efficiency of the power supply.

Further, a boosting capacitor (C) is connected between two voltage output terminals (104) and (105) in the switching power supply circuit (101), and a chopper circuit (11) is connected.
3) Or the voltage supplied from the bypass circuit (112) is charged. Since the chopper circuit (113) performs step-up or step-down by the switch element (123), the charging voltage to the step-up capacitor (C) includes a fluctuation component. The boosting capacitor (C) also has a function of smoothing the fluctuating voltage and supplying the smoothed voltage to the amplifier circuit (102).

When the above-mentioned circuit is used as a vehicle-mounted or other audio amplifier, it is necessary to hybridly integrate circuit elements on a printed circuit board or the like. In particular, the space for mounting the audio device is limited in vehicles,
There is a demand for miniaturization of circuit boards. In this case, since a normal printed circuit board is too large, formation of a circuit on a smaller thick film substrate is being studied. However, the coil (L)
Since the step-up capacitor (C) is large, it is difficult to directly mount the capacitor on the thick-film substrate. Therefore, it is necessary to separate the thick-film substrate from the thick-film substrate and connect it separately to an amplifier circuit formed on the thick-film substrate.

The boosting capacitor (C) is externally mounted on a thick film substrate as shown in the plan view of FIG. That is, one end is connected to the first voltage output terminal (104) of the switching power supply circuit (101), and the other end is connected to the first voltage output terminal (104) of the amplifier circuit (102).
Wiring (13) connected to the voltage input terminal (106)
a) is formed on the thick film substrate (11), and a branch wiring (13b) is formed from the first wiring (13a) and terminated at an end of the thick film substrate (11). The second wiring (14a) connected to the second voltage output terminal (105) of the switching power supply circuit (101) and the third wiring connected to the second voltage input terminal (107) of the amplifier circuit (102). The wiring (14b) is formed on the thick film substrate (11) and terminated at the end.

Then, on the printed circuit board (12), a fourth wiring (15) connected to the branch wiring (13b) and a second wiring (15) are formed.
Fifth connecting the third wiring (14b) with the third wiring (14a)
Are formed, and a boosting capacitor (C) is connected by bridging between them. Such a thick film substrate (1)
A hybrid integrated circuit device is formed by 1) and the printed circuit board (12).

The operation of the amplifier will be briefly described with reference to FIGS. That is, when the amplified signal (ZS) is small, the switch element (123) is off and the DC
The constant voltage generated by the / DC converter circuit (111) is supplied as a power supply voltage (± Vc) to the amplifier circuit (102) via the bypass circuit (112). Amplified signal (Z
S) becomes a large output, and the potential (V) at point a in FIG.
When the potential difference (Va-ZS) between a) and the amplified signal (ZS) becomes equal to or less than a predetermined voltage, the comparison circuit (114) starts the on / off operation of the switch element (123).

The chopper circuit (112) operates by the on / off operation of the switch element (123) to boost the constant voltage (± Vb). That is, the first wiring (13a)
, A branch wiring (13b), a fourth wiring (15), a boost capacitor (C), a fifth wiring (16), a second wiring
The boosting capacitor (C) is charged through the wiring (14a), and the potential (Va) at point a in FIG. 3 rises. Further, the charging voltage of the boosting capacitor (C) is set to the fourth wiring (15), the branch wiring (13b), the first wiring (13a), the amplifier circuit (102), and the third wiring (1).
4b) and the fifth wiring (16), the discharged and boosted voltage is supplied to the amplifier circuit (102) by the power supply voltage (± V
c). Thereby, the amplified signal (ZS)
The power supply voltage (± Vc) corresponding to the magnitude of the amplifier circuit (10
2), and the input signal (AS) is amplified.

[0010]

However, in the above hybrid integrated circuit device, the switch element (12
Since the step-up or step-down is performed according to 3), the voltage fluctuates when charging the step-up capacitor (C). Therefore, FIG.
As shown in (2), the power supply voltage (± Vc) supplied to the amplifier circuit (102) is also affected by the fluctuation. For this reason, since the ground potential fluctuates and is superimposed on the amplified signal (ZS) as it is, there is a problem that the signal is not faithfully amplified and reproduced.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is a first invention of the first invention, in which a first positive voltage output terminal and a negative voltage output terminal are connected. A switching power supply circuit having a second voltage output terminal;
A power supply voltage input terminal and an amplifier circuit having a second power supply voltage input terminal on the negative side are formed on a thick film substrate, and the first voltage output terminal and the first power supply voltage input terminal are A terminal connected to one end of an external capacitor for boosting an output voltage of the switching power supply circuit, wherein the second voltage output terminal and the second power supply voltage input terminal are terminals connected to the other end of the capacitor A switching power supply circuit and an amplifier circuit are formed on a thick film substrate by a hybrid integrated circuit device, and a power supply voltage supplied to the amplifier circuit when a boosting capacitor is separately connected to those circuits. It is an object of the present invention to provide a hybrid integrated circuit device capable of preventing fluctuations and faithfully amplifying and reproducing an input signal.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial plan view showing a hybrid integrated circuit device on which other audio amplifiers for vehicle use according to an embodiment of the present invention are formed. The switching power supply circuit and the amplifier circuit are formed on a thick film substrate, and the boosting capacitor (C) is mounted on a printed circuit board different from the thick film substrate and connected to the circuit on the thick film substrate. FIG. 2 is a diagram illustrating an output signal waveform of an on-vehicle audio amplifier. FIG. 3 is a schematic diagram showing a circuit configuration of an on-vehicle audio amplifier.

As shown in FIG. 3, a first positive voltage output terminal (104) and a second negative voltage output terminal (105) are provided.
And a first power supply voltage input terminal (10) on the positive side, which is connected to the first and second voltage output terminals (104) and (105), respectively.
6) and an amplifier circuit (102) having a negative second power supply voltage input terminal (107). The amplified signal output from the amplifier circuit (102) is output from the speaker (103).
Supplied to

The switching power supply circuit (101)
A DC / DC converter circuit (111) for generating a constant voltage (± Vb) of V, and a DC / DC converter circuit (11
Chopper circuit (113) for boosting the constant voltage (± Vb) generated by 1), and DC / DC converter circuit (111)
The constant voltage (± Vb) generated by the amplifier circuit (10
2) a bypass circuit (112), and a comparison circuit (114) as a selection switching circuit for controlling the operation of the switch element (123) of the chopper circuit (113).

The chopper circuit (113) has the following circuit configuration. Coil (L) and diode (12
2) is connected in series to one voltage output terminal (124) of the DC / DC converter circuit (111). The diode (122) is connected in such a direction that the current easily flows from the DC / DC converter circuit (111) to the amplifier circuit (102), and the cathode side of the diode (122) is the first voltage output of the switching power supply circuit (101). It becomes a terminal (104). Further, the switch element (123) is connected so as to bridge the connection between the coil (L) and the diode (122) and the second voltage output terminal (105). As the switch element (123), for example, an insulated gate field effect transistor is used. The boosting capacitor (C) includes a first voltage output terminal (104) and a second voltage output terminal (1
05) are connected.

The bypass circuit (112) comprises a coil (L) of a chopper circuit (113) and a diode (121) connected in parallel to the diode (122). The diode (121) is connected in a direction in which a current easily flows from the DC / DC converter circuit (111) to the amplifier circuit (102). The positive input terminal of the comparison circuit (114) is connected to point a in FIG. 3, and the negative input terminal is connected to the amplifier circuit (1).
02) is connected to the amplified signal output terminal. The output terminal of the comparison circuit (114) is a switch element (123).
It is connected to the. The amplified signal (ZS) and the potential (Va) at point a in FIG. 3 are constantly detected, and the potential difference (Va−Z
When S) becomes equal to or lower than a predetermined voltage (5 V), the on / off operation of the switch element (123) is started.
23) has a function of stopping the on / off operation.

The amplifier circuit (102) is a circuit that amplifies the input signal (AS) to generate an amplified signal (ZS) and outputs the amplified signal (ZS) to a 4Ω speaker (103). Next, with reference to FIG. 1, the arrangement of wiring on the thick film substrate for externally attaching the boosting capacitor (C) to the circuit formed on the thick film substrate and the mounting of the boosting capacitor (C) The method will be described.

As shown in FIG. 1, a chopper circuit (11
3) The first wiring (3a) connected to the first voltage output terminal (104) and the second wiring (4a) connected to the second voltage output terminal (105) are the thick film substrate (1). Formed on the substrate and terminated at the ends of the thick film substrate (1). A third wiring (3b) connected to the first power supply voltage input terminal (106) of the amplifier circuit (102) and a fourth wiring (4) connected to the second power supply voltage input terminal (107).
b) are separately formed on the thick film substrate (1) and terminate at the ends of the thick film substrate (1).

A printed circuit board (2) on which a boosting capacitor (C) is mounted is prepared separately from the thick film board (1).
A fifth wiring (5) and a sixth wiring (6) are separately formed on the printed board (2), and both ends of each of the wirings (5) and (6) are both ends of the printed board (2). Is terminated.
The boosting capacitor (C) bridges and connects the fifth wiring (5) and the sixth wiring (6).

Both ends of the fifth wiring (5) are respectively connected to the first wiring (3a) and the third wiring (3b) of the thick film substrate (1).
And both ends of the sixth wiring (6) are connected to the second wiring (4a) and the fourth wiring (4b) of the thick film substrate (1), respectively.
Is connected to As a result, the boosting capacitor (C) is connected between the two voltage output terminals (104) and (105) of the switching power supply circuit (101) and the amplifier circuit (1).
02) of the two power supply voltage input terminals (106) and (10).
7) It is connected by bridging between them.

The operation of the above circuit will be described below with reference to FIGS. 2, 1 and 5. First, when the power is turned on, a constant voltage of 12 V is supplied to this circuit from the DC / DC converter circuit (111). At this time, the switch element (123) is off and the amplifier circuit (10
2), a constant voltage generated by the DC / DC converter circuit (111) is supplied as a power supply voltage (± Vc) via a bypass circuit (112). As a result, the input signal (AS) is amplified, and an amplified signal (ZS) is output from the amplifier circuit (102).

At this time, the potential difference (Va-ZS) between the potential (Va) at point a in FIG. 5 and the amplified signal (ZS) is always detected by the comparison circuit (114), and this potential difference (Va-ZS) is detected. The switching element (123) is operated or its operation is stopped depending on whether the value of ()) is smaller or larger than a predetermined voltage (5V). That is, the amplified signal (ZS) has a relatively small level and the potential difference (Va−Z).
When S) becomes equal to or higher than a predetermined voltage, the comparison circuit (11)
4) stops the operation of the switch element (123) and supplies the constant voltage (Vb) to the amplifier circuit (102) via the bypass circuit (112).

When the level of the amplified signal (ZS) becomes a large output and the potential difference (Va-ZS) falls below a predetermined voltage,
The comparison circuit (114) turns on / off the switch element (123).
Start off operation. Such a switch element (12
Chopper circuit (113) by ON / OFF operation of 3)
Operates to increase the constant voltage (± Vb). At this time, the boosting capacitor is passed through the first wiring (3a), the fifth wiring (5), the boosting capacitor (C), the sixth wiring (6), and the second wiring (4a). (C) is being charged, and the potential (Va) at point a in FIG. 5 rises. Further, the charging voltage of the boosting capacitor (C) is supplied to the fifth wiring (5), the third wiring (3b), and the amplifier circuit (102).
Then, the voltage is discharged through the fourth wiring (4b) and the sixth wiring (6), and the boosted voltage is supplied to the amplifier circuit (102) as a power supply voltage. At this time, as shown in FIG. 1, the first wiring (3a) connected to the first voltage output terminal (104) and the first power supply voltage input terminal (10
6) is formed on the thick film substrate (1) separately from the third wiring (3b) connected to the third wiring (3b).
The second wiring (4a) connected to 5) and the fourth wiring (4b) connected to the second power supply voltage input terminal (107) are separately formed on the thick film substrate (1). As a result, both charging and discharging of the positive and negative voltages are performed through separate paths. For this reason, the fluctuation of the voltage at the time of charging is smoothed by the boosting capacitor (C), and the amplified circuit (1)
02), a power supply voltage (± Vc) with small fluctuation is supplied. As a result, the input signal (AS) is amplified, and an amplified signal (ZS) with small fluctuation as shown in FIG. 2 is output from the amplifier circuit (102).

Again, when the level of the amplified signal (ZS) becomes a small output and the potential difference (Va-ZS) exceeds a predetermined voltage (5 V), the comparator (114) switches the switch element (12).
The on / off operation of 3) is stopped, and the amplification circuit (102)
Is supplied with a constant voltage again through the bypass circuit (112). As a result, the input signal (AS) is amplified, and an amplified signal (ZS) is output from the amplifier circuit (102).

As described above, in the hybrid integrated circuit device in which the vehicle-mounted audio amplifier according to the embodiment of the present invention is formed on a thick film substrate, the first voltage output terminal ( The first wiring (3a) connected to the first wiring 104) and the third wiring (3b) connected to the first power supply voltage input terminal (106) of the amplifier circuit (102) are separately thick films. It is formed on a substrate (1) and terminates at its ends.

Therefore, these wirings (3a) and (3b)
The boosting capacitor (C) externally connected is charged and discharged through separate paths. For this reason, the voltage fluctuation at the time of charging is smoothed by the boosting capacitor (C), and the power supply voltage (± Vc) with small fluctuation is supplied to the amplifier circuit (102). As a result, the ground potential is stabilized, and the amplified signal (Z
Since S) is output, the input signal can be faithfully amplified and reproduced.

[0027]

As described above, in the hybrid integrated circuit device of the present invention, the positive first voltage output terminal of the switching power supply circuit and the positive first power supply voltage input terminal of the amplifier circuit are used for boosting. A terminal connected to one end of the capacitor, and a second voltage output terminal on the negative side of the switching power supply circuit and a second power supply voltage input terminal on the negative side of the amplifier circuit are terminals connected to the other end of the boosting capacitor. .

Therefore, the charging and discharging of the positive and negative voltages to the externally connected boosting capacitor are performed via separate paths. For this reason, the voltage fluctuation at the time of charging is smoothed by the boosting capacitor, and the power supply voltage with small fluctuation is supplied to the amplifier circuit, so that the ground potential is stabilized, and an amplified signal with small fluctuation is output from the amplifier circuit. You. As a result, the input signal can be faithfully amplified and reproduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing a form of wiring on a thick film substrate for externally attaching a boosting capacitor of a switching power supply circuit according to a first embodiment of the present invention to the thick film substrate.

FIG. 2 is a voltage waveform diagram showing an amplified signal of the audio amplifier according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a circuit configuration of a switching power supply circuit and an amplifier circuit portion of the audio amplifier.

FIG. 4 is a plan view showing a form of wiring on a thick film substrate for externally attaching a boosting capacitor of a switching power supply circuit of an audio amplifier according to a conventional example to the thick film substrate.

FIG. 5 is a voltage waveform diagram showing an amplified signal of an audio amplifier according to a conventional example.

[Explanation of symbols]

(1) Thick film substrate (2) Printed circuit board (3a) First wiring (3b) Third wiring (4a) Second wiring (4b) Fourth wiring (5) Fifth wiring (6) Wiring 6 (101) Switching power supply circuit (102) Amplifier circuit (103) Speaker (104) First voltage output terminal (105) Second voltage output terminal (106) First power supply voltage input terminal (107) 2 power supply voltage input terminals (111) DC / DC converter circuit (112) bypass circuit (113) chopper circuit (114) comparison circuit (121, 122) diode (123) switch element (124, 125) DC / DC converter circuit Voltage output terminal (C) Boost capacitor (L) Coil

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 1/02

Claims (1)

(57) [Claims] A first voltage output terminal on a positive side and a second voltage output terminal on a negative side;
A switching power supply circuit having a first voltage input terminal and a amplifier circuit having a first power supply voltage input terminal on the positive side and a second power supply voltage input terminal on the negative side are formed on a thick film substrate; and A first voltage output terminal and the first power supply voltage input terminal are terminals connected to one end of an external capacitor that boosts an output voltage of the switching power supply circuit;
A hybrid integrated circuit device, wherein the second voltage output terminal and the second power supply voltage input terminal are terminals connected to the other end of the capacitor.