CN1089967C - Amplifier circuit for sound frequency signal - Google Patents
Amplifier circuit for sound frequency signal Download PDFInfo
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- CN1089967C CN1089967C CN 97111852 CN97111852A CN1089967C CN 1089967 C CN1089967 C CN 1089967C CN 97111852 CN97111852 CN 97111852 CN 97111852 A CN97111852 A CN 97111852A CN 1089967 C CN1089967 C CN 1089967C
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- audio signal
- signal
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- amplifier circuit
- transistor
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Abstract
To decrease the number of component parts of an audio signal amplifier circuit by securing the high-pass active filter characteristic with respect to a 2nd audio signal for an amplifier transistor TR, which performs the shared amplification of both 1st and 2nd audio signals. When the 1st audio signal selection voltage is supplied to a 1st audio signal selection voltage supply terminal 17, a 1st switching diode 10 is turned on. Then a 2nd switching diode 15 is turned on, when the 2nd audio signal selection voltage is supplied to a 2nd audio signal selection voltage supply terminal 18, and the selection voltage is amplified by an amplifier TR 1 and outputted to a signal output terminal 6. An audio signal amplifier circuit consists of the TR 1, the 1st and 2nd capacitors 12 and 13 and a feedback resistance 14 and has a high-pass active filter characteristic. Thus, the constitution is simplified, and the number of component parts for the amplifier circuit can be decreased.
Description
The present invention relates to a kind of amplifier circuit for sound frequency signal, the particularly amplification of the 1st audio signal after the demodulation of frequency-modulation broadcasting signal and the 2nd audio signal after the demodulation of amplitude modulation broadcast singal eliminated its stereo auxiliary signal and amplify can be carried out selectively.
Generally in the amplitude modulation broadcasting signal, when carrying out stereophonic broadcasting, insert stereo auxiliary signal, expression belongs to stereophonic broadcasting.Therefore, amplitude modulation/fm broadcast receiver etc. when receiving the amplitude-modulated stereo broadcast singal, can remaining frequency be the stereo auxiliary signal composition of 25Hz in the audio signal after demodulation.
So frequency modulation/amplitude modulation broadcasting receiver in the past when the audio signal after the demodulation of amplitude modulation broadcast singal is amplified, in order to eliminate stereo auxiliary signal composition, use the amplifier circuit for sound frequency signal with high pass filter characteristic.
Fig. 3 represents the circuit diagram of the example that the amplifier circuit for sound frequency signal with high pass filter characteristic in the past constitutes.
The transistor 1 of the amplification usefulness of grounded emitter type is exactly audio signal (below be referred to as the 1st audio signal) after the demodulation of frequency-modulation broadcasting signal and the audio signal after the demodulation of amplitude modulation broadcasting signal (below be referred to as the 2nd an audio signal) amplifier selectively.Amplify the transistor 1 of usefulness, its emitter connects with earth point by earth resistance 2, its collector electrode by resistance 3 with power supply terminal 19, pass through coupling capacitance 5 and connect respectively with signal output terminal 6, its base stage is passed through biasing resistor 4 and is connected with earth point.The 1st audio signal input end 7, the base stage of amplifying the transistor 1 of usefulness by coupling capacitance 8 and the 1st switching diode 10 together links, and the interface of coupling capacitance 8 and the 1st switching diode 10 selects voltage supply terminal 17 to link by resistance 9 with the 1st audio signal.
In addition, the grounded emitter type amplifies the transistor 20 of usefulness, when amplifying the 2nd audio signal, constitutes the high pass active filter.Amplify the transistor 20 of usefulness, its emitter links with earth point by earth resistance 21, collector electrode is selected voltage supply terminal 18 by resistance 23 with the 2nd audio signal and is linked respectively by coupling capacitance 22 and the 2nd switching diode 15 base stage with the transistor 1 that amplifies usefulness, and its base stage connects respectively with earth point with the 2nd audio signal feeding terminal 18 and by biasing resistor 25 by biasing resistor 24.The 2nd audio signal input end 11 links by the 1st and the 2nd electric capacity 12, the 13 same base stages of amplifying the transistor 20 of usefulness of mutual series connection, and the interface of the 1st and the 2nd electric capacity 12,13 links by the emitter of feedback resistance 14 with the transistor 20 that amplifies usefulness.The interface of coupling capacitance 22 and the 2nd switching diode 15 selects voltage supply terminal 18 to link by resistance 16 with the 2nd audio signal.Like this, the transistor the 20, the 1st of utilization amplification usefulness and the 2nd electric capacity 12,13 and feedback resistance 14 have just constituted the high pass active filter.
Now, select voltage (FMsw) (at this moment, selecting voltage supply terminal 18 not apply any voltage to the 2nd audio signal) if select voltage supply terminal 17 to apply the 1st audio signal for the 1st audio signal, then the 1st switching diode 10 just is in on-state.At this moment,,, put on the transistor 1 that amplifies usefulness, after the transistor 1 through amplifying usefulness amplifies, export from signal output terminal 6 by coupling capacitance 5 by coupling capacitance the 8, the 1st switching diode 10 in the 1st audio signal of sub 7 inputs of the 1st audio signal input end.
On the other hand, select voltage (AMsw) (at this moment selecting voltage supply terminal 17 not apply any voltage) if select voltage supply terminal 18 to apply the 2nd audio signal for the 2nd audio signal to the 1st audio signal, the transistor 20 that then amplifies usefulness just is in operating state, simultaneously, the 2nd switching diode 15 also is in on-state.At this moment,,, put on the base stage of the transistor 20 that amplifies usefulness, amplify by the transistor 20 that amplifies usefulness through the 1st and the 2nd electric capacity 12,13 in the 2nd audio signal of the 2nd audio signal input end 11 inputs.Then, the 2nd audio signal puts on the base stage of the transistor 1 that amplifies usefulness by coupling capacitance 22 and the 2nd switching diode 15, after the transistor 1 through amplifying usefulness amplifies, exports from signal output terminal 6 by coupling capacitance 5.
Like this, when the 2nd audio signal is amplified, the high pass active filter that utilization is made of the transistor the 20, the 1st that amplifies usefulness and the 2nd electric capacity 12,13 and feedback resistance 14, the composition of frequency below 25Hz of the 2nd audio signal decayed, suppressed the output of the auxiliary signal composition of frequency 25Hz.
Above-mentioned amplifier circuit for sound frequency signal in the past, when amplifying the 2nd audio signal, at first to utilize the transistor 20 of the amplification usefulness that constitutes the high pass active filter to amplify, amplify with the transistor 1 that amplifies usefulness again then, thereby its problem is that not only the circuit composition is complicated, and element is many, the manufacturing cost height.
The present invention is exactly in order to address the above problem, and its objective is provides a kind of circuit of simplifying to form, and reduces the amplifier circuit for sound frequency signal of element, reduction manufacturing cost.
For achieving the above object, amplifier circuit for sound frequency signal of the present invention, utilization can be amplified selectively to the 1st and the 2nd audio signal, grounded emitter type amplifies uses transistor, when the 2nd audio signal is amplified, comprise this amplification transistor, constitute a high pass active filter the 2nd audio signal.
According to above-mentioned formation, amplification to the 1st and the 2nd audio signal, it is with the transistor of same amplification usefulness, and make it to have characteristic to the high pass active filter of the 2nd audio signal, so just can obtain entire circuit form simplify, element quantity reduces, amplifier circuit for sound frequency signal cheap for manufacturing cost.
In an embodiment of the present invention, amplifier circuit for sound frequency signal includes: 1. amplify the transistor of usefulness, its base stage can be imported the 1st or the 2nd audio signal selectively, and emitter is by grounding through resistance, and the 1st or the 2nd audio signal is exported by collector electrode; 2. the 1st and the 2nd electric capacity is connected between the transistorized base stage of the 2nd audio signal input end and amplification usefulness; 3. feedback resistance is connected in the interface of the 1st and the 2nd electric capacity and amplifies between the transistorized emitter of usefulness; Utilize the transistor that amplifies usefulness, the 1st and the 2nd electric capacity and feedback resistance constitutes the high pass active filter to the 2nd audio signal.
In addition, in the preferred example of example of the present invention, amplifier circuit for sound frequency signal is as follows: between the transistorized base stage of the 1st audio signal input end and amplification usefulness, connecting the 1st switch; Between the transistorized base stage of the 1st and the 2nd electric capacity of connecting mutually and amplification usefulness, connecting the 2nd switch; The the 1st and the 2nd switch both one of under the admittance state, start selectively, the transistor that utilize to amplify usefulness selectively amplifies the 1st audio signal or the 2nd audio signal.
Furthermore, in instantiation of the invention process, amplifier circuit for sound frequency signal is as follows: the 1st audio signal is the restituted signal of fm broadcast signal, the 2nd audio signal is the restituted signal of amplitude modulation broadcasting signal, and the high pass active filter can be eliminated the stereo auxiliary signal in the restituted signal of amplitude modulation broadcasting signal.
According to these embodiment, when the transistor that the 1st and the 2nd audio signal utilization is amplified usefulness amplifies selectively, the 1st audio signal uses the transistor that amplifies usefulness to amplify, and the 2nd audio signal uses the transistor of the amplification usefulness with high-pass type active filter characteristic to carry out the one-level amplification.In other words, the 2nd audio signal, and, use the transistor of auxiliary amplification usefulness to amplify with high pass active filter characteristic unlike in the past amplifier circuit for sound frequency signal, more particularly, be not to use the transistor that amplifies usefulness to carry out two utmost points to amplify.
Therefore, obtained to compare with amplifier circuit for sound frequency signal in the past, quantity reduces amplifier circuit for sound frequency signal cheap for manufacturing cost thereby integrated circuit is formed the simplification element.
Below, to embodiments of the invention, be illustrated with reference to diagram.
Fig. 1 represents the forming circuit figure according to examples of implementation of amplifier circuit for sound frequency signal of the present invention.
Fig. 2 represents the performance plot of the necessary band signal amplification characteristic of amplifier circuit for sound frequency signal.
Fig. 3 represents the circuit diagram of the example that amplifier circuit for sound frequency signal in the past constitutes.
In the amplifier circuit for sound frequency signal of present embodiment shown in Figure 1, when identical in its element and the amplifier circuit for sound frequency signal example in the past that Fig. 3 represents, then mark same code name.
Picture as shown in Figure 1, in the amplifier circuit for sound frequency signal of present embodiment, the 2nd audio signal (audio signal after the demodulation of amplitude modulation broadcasting signal) input terminal 11, by the 1st, the 2nd electric capacity 12,13 and the 2nd switching diode 15 of mutual series connection, the base stage of amplifying the transistor 1 of usefulness together links; 1st, the interface of the 2nd electric capacity 12,13 links by the emitter of feedback resistance 14 with the transistor 1 that amplifies usefulness; The interface of the 2nd electric capacity 13 and the 2nd switching diode 15 selects voltage supply terminal 18 to link by resistance 16 with the 2nd audio signal.Like this, utilize transistor the 1, the 1st, the 2nd electric capacity 12,13 and the feedback resistance 14 that amplifies usefulness, constituted the high-pass type active filter.In addition, in the amplifier circuit for sound frequency signal of present embodiment, the part beyond these circuit are formed, identical with audio amplifier circuit in the past shown in Figure 3, so the explanation that those circuit are formed is omitted.
Press the amplifier circuit for sound frequency signal of present embodiment of above-mentioned formation, it is as follows to make situation mutually:
When receiving fm broadcast signal, (at this moment select voltage supply terminal 18 not apply any voltage to the 2nd audio signal) when selecting voltage supply terminal 17 to apply the 1st audio signal selection voltage (FMsw) to the 1st audio signal, the 1st switching diode 10 just is in on-state.At this moment, the 1st audio signal from 7 inputs of the 1st audio signal input end, by coupling capacitance the 8, the 1st switching diode 10, put on the base stage of the transistor 1 that amplifies usefulness, after transistor 1 through amplifying usefulness amplifies, export to subsequent conditioning circuit (not expression on the figure) from signal output terminal 6 by coupling capacitance 5.
Corresponding, when receiving the amplitude modulation broadcasting signal, (at this moment select voltage supply terminal 17 not apply any voltage to the 1st audio signal) when selecting voltage supply terminal 18 to apply the 2nd audio signal selection voltage (AMsw) to the 2nd audio signal, the 2nd switching diode 15 just is in on-state.At this moment, the 2nd audio signal from 11 inputs of the 2nd audio signal input end, the the 1st, the 2nd electric capacity 12,13 and the 2nd switching diode 15 by mutual series connection, put on the base stage of the transistor 1 that amplifies usefulness, after transistor 1 through amplifying usefulness amplifies, export to subsequent conditioning circuit (not diagram) from signal output terminal 6 by coupling capacitance 5.In addition, the part of the 2nd audio signal, the emitter by the transistor 1 that amplifies usefulness by feedback resistance 14, feeds back to the interface of the 1st, the 2nd electric capacity 12,13.
Here, the capacity of the 1st, the 2nd electric capacity 12,13 is respectively C
1, C
2, the resistance of feedback resistance 14 is R
1, for example, select C
1=0.033 μ F, C
2=0.1 μ F, R
1During=10K Ω, have wave band amplification characteristic by the amplification circuits of transistor the 1, the 1st, the 2nd electric capacity 12,13 that amplifies usefulness and the high pass active filter characteristic that feedback resistance 14 constitutes, for the 1st audio signal just like the curve of Fig. 2 1. shown in, for the 2nd audio signal just like the curve of Fig. 2 2. shown in.So being the stereo auxiliary signal composition of 25Hz, the frequency that the 2nd audio signal is contained just decayed widely.
Like this, according to present embodiment, utilize 1 pair the 1st in the transistor and the 2nd audio signal of amplifying usefulness to amplify selectively, and constitute amplifying circuit for the 2nd audio signal with high pass active filter characteristic, so obtained circuit form simple, element quantity reduces, amplifier circuit for sound frequency signal cheap for manufacturing cost.
As described above, according to the present invention, utilize the transistor that amplifies usefulness to the 1st and the 2nd audio signal Amplify selectively, have the high-pass type active filter and consist of for the 2nd audio signal The amplifying circuit of characteristic is so with comparing with the amplifier circuit for sound frequency signal of living, its effect is: obtain Thereby got integrated circuit and formed the minimizing of simplification element quantity, audio frequency letter cheap for manufacturing cost Number amplifying circuit.
Claims (4)
1. amplifier circuit for sound frequency signal comprises: 1. be used to the transistor that amplifies, its base stage can be imported the 1st or the 2nd audio signal selectively, and its emitter is by ground resistance earth, and the above-mentioned the 1st or the 2nd audio signal is exported by collector electrode; 2. the 1st and the 2nd electric capacity is connected between the 2nd audio signal input end and the above-mentioned transistorized base stage that is used to amplify; 3. feedback resistance, be connected in the above-mentioned the 1st and the interface and the above-mentioned transistorized emitter that is used to amplify of the 2nd electric capacity between; It is characterized in that: utilize described amplification with transistor, the described the 1st and the 2nd electric capacity and described feedback resistance, form high pass active filter for above-mentioned the 2nd audio signal.
2. according to the amplifier circuit for sound frequency signal of claim 1, it is characterized in that: also comprise the 1st switch between the transistorized base stage that is connected in the 1st audio signal input end and above-mentioned amplification usefulness, be connected in the 2nd switch between the transistorized base stage of the 1st and the 2nd electric capacity of above-mentioned mutual series connection and above-mentioned amplification usefulness, the the 1st and the 2nd switch both one of under conducting state, start selectively, utilize the transistor of above-mentioned amplification usefulness, described the 1st audio signal or the 2nd audio signal are amplified selectively.
3. according to the amplifier circuit for sound frequency signal of claim 2, it is characterized in that: described the 1st audio signal is the restituted signal of frequency modulation (FM) broadcast singal, above-mentioned the 2nd audio signal is the restituted signal of amplitude modulation (AM) broadcast singal, and above-mentioned high pass active filter can be eliminated the stereo auxiliary signal in the restituted signal of described amplitude modulation broadcasting signal.
4. according to the amplifier circuit for sound frequency signal of claim 1, it is characterized in that: described the 1st audio signal is the restituted signal of fm broadcast signal, above-mentioned the 2nd audio signal is the restituted signal of amplitude modulation broadcasting signal, and described high pass active filter can be eliminated the stereo auxiliary signal in the restituted signal of above-mentioned amplitude modulation broadcasting signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15819196A JP3339546B2 (en) | 1996-06-19 | 1996-06-19 | Audio signal amplifier circuit |
| JP158191/96 | 1996-06-19 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1169061A CN1169061A (en) | 1997-12-31 |
| CN1089967C true CN1089967C (en) | 2002-08-28 |
Family
ID=15666264
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 97111852 Expired - Fee Related CN1089967C (en) | 1996-06-19 | 1997-06-19 | Amplifier circuit for sound frequency signal |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3339546B2 (en) |
| CN (1) | CN1089967C (en) |
| MY (1) | MY118005A (en) |
-
1996
- 1996-06-19 JP JP15819196A patent/JP3339546B2/en not_active Expired - Fee Related
-
1997
- 1997-06-13 MY MYPI9702662 patent/MY118005A/en unknown
- 1997-06-19 CN CN 97111852 patent/CN1089967C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| MY118005A (en) | 2004-08-30 |
| CN1169061A (en) | 1997-12-31 |
| JPH1013264A (en) | 1998-01-16 |
| JP3339546B2 (en) | 2002-10-28 |
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