JPH0763153B2 - AM / FM receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a semiconductor integrated circuit in which an AM / FM receiver has an AM and FM intermediate frequency section formed on the same chip.

[Conventional technology]

Fig. 2 shows a conventional example of an AM / FM receiver. In FIG. 2, reference numerals 1 and 3 are AM and FM receiving antennas, 2, 4 are AM and FM high-frequency amplifier circuits, and 5 and 8 are AM and FM intermediate frequency sections. Reference numerals 6 and 9 denote AM and FM intermediate frequency processing circuits, respectively, and 11 denotes a switching circuit for switching the operation of the AM intermediate frequency section 5 and the FM intermediate frequency section 8.
In addition, T1 and T2 indicate AM and FM intermediate frequency output terminals, respectively, and T3 indicates a control signal input terminal of the switching circuit. Next, this conventional example will be described. As shown in Fig. 2, the AM / FM receiver has a recent technical trend. As shown in Fig. 2, the AM and FM intermediate frequency units 5 and 8 are externally attached to the semiconductor integrated circuit 12 configured on the same chip.
The mainstream is a configuration in which high-frequency amplifier circuits 2 and 4 for FM and FM are connected. Considering the case of receiving either AM broadcast or FM broadcast in FIG. 2 here, assuming that it is AM broadcast.
A control signal is input from the control signal input terminal T3 to the switching circuit 11 for switching the operation between the AM intermediate frequency section 5 and the FM intermediate frequency section 8,
The AM intermediate frequency unit 5 is in the operating state, and the FM intermediate frequency unit 8 is in the stopped state. However, for AM connected externally, F
The high frequency amplifier circuits 2 and 4 for M have the power supply terminals as the switching circuit.
Since they are not controlled by 11, both are in the operating state. In this case, the operation of the FM high-frequency amplifier circuit 4 is unnecessary, and there is a drawback that the power loss due to the current consumed here makes the total power consumption of the AM / FM receiver large. This is because the operation of the AM high-frequency amplifier circuit 2 is not necessary even when operating as an FM receiver, and the above-mentioned drawbacks occur.

[Problems to be solved by the invention]

An object of the present invention is to obtain power saving of an AM / FM receiver configured by using a semiconductor integrated circuit in which the AM intermediate frequency section and the FM intermediate frequency section as described above are configured on the same chip.

[Means for solving problems]

The present invention is for AM and F in which an AM intermediate frequency section 5 and an FM intermediate frequency section 8 are connected to a semiconductor integrated circuit 12 configured on the same chip.
AM intermediate frequency unit 5 and FM for controlling M high-frequency amplifier circuits 2 and 4
The gain control circuits 7 and 10 inside the intermediate frequency section 8 are respectively connected, and the operations of the AM and FM intermediate frequency signal processing circuits 6 and 9 and the AM and FM intermediate frequency sections 5 and 8 are controlled as the gain control circuits 7 and 10, respectively. An AM / FM receiver characterized by being connected to a switching circuit 11 for switching.

〔Example〕

 The present invention will now be described in more detail with reference to the drawings.

FIG. 1 shows the principle of the present invention. In FIG. 1, the AM intermediate frequency part 5 and the FM intermediate frequency part 8 in the semiconductor integrated circuit 12 are AM
And AM high frequency amplifier circuits 2 and 4 are connected to the AM intermediate frequency section 5 and the FM intermediate frequency section 8 inside the gain control circuits 7 and 10, respectively. It is connected. The gain control circuits 7 and 10 are connected to a switching circuit 11 for switching the operation of the AM intermediate frequency section 5 and the FM intermediate frequency section 8. Next, the principle of operation according to the present invention will be described. First, supposing that the AM receiver operates as an AM receiver, the switching circuit 11 for switching the operation controls the AM intermediate frequency section 5 to the operating state and the FM intermediate frequency section 8 to the stop state. At this time, the gain control circuit 10 inside the FM intermediate frequency unit 8
Does not operate according to the control input signal from the FM intermediate frequency signal processing circuit 9, but enters the operating state according to the control input signal from the switching circuit 11 for switching the operation. As a result, the operation of the high-frequency amplifier circuit 4 for FM, which has been in the operating state in the conventional AM reception, is controlled and brought into a stopped state. The same applies to the case where the FM receiver operates. As a result, the operation of the high frequency amplifier circuit that is not on the receiving side can be controlled, and the total power consumption of the AM / FM receiver can be reduced.

Next, FIGS. 3 and 4 will be described as specific circuit embodiments. First, FIG. 3 is a high-frequency amplifier circuit according to the present invention (corresponding to the high-frequency amplifier circuits 2 and 4 for AM and FM in FIG. 1).
Indicates. In FIG. 3, the input signal from the receiving antenna is amplified by the transistor Q10 input to the input terminal T5 connected to the gate of the source-grounded high frequency amplification transistor Q10. Where R1 is the bias resistor and C1,
The resonant circuit formed by L1 is the output resistance of the transistor Q10. The transistor Q1 connected between the drain of the transistor Q10 and the resonant circuit is
Is a transistor for controlling the drain current of the transistor Q10 by the control voltage input to the control signal output terminal T6 connected to the base of the transistor Q10 and thereby controlling the gain of the transistor Q10. The terminal T7 is an output terminal of the high frequency amplifier circuit, and T4 is a power supply terminal.

Next, FIG. 4 shows a specific example of the switching circuit 11 in the semiconductor integrated circuit 12 shown in FIG. In FIG. 4, consider a case where the AM intermediate frequency unit 5 is in the operating state and the FM intermediate frequency unit 8 is in the stopped state. In this case, the control signal input terminal T3 of the switching circuit
A voltage signal that is sufficiently lower than the reference voltage terminal T8 is input to. Then, the transistor Q6 side of the transistors Q6 and Q7, which are a differential pair in the switching circuit, is turned off, the transistor Q7 side is turned on, and the transistor Q4 connected to the collector of the transistor Q6 side is turned off.
The transistor Q5 connected to the collector on the Q7 side is turned on. Next, the output current of the switching circuit is not input to the bases of the transistors Q2 and Q3 connected to the emitters of the transistors Q4 and Q5 on the transistor Q2 side, and the output of the switching circuit is on the transistor Q3 side. The current is input and it turns on. As a result, at the control output terminal T6 side, the voltage level changed by the control signal from the AM intermediate frequency section is output without being affected by the control signal from the switching circuit, and at the control output terminal T6 'side, the FM intermediate frequency section operates. It is not affected by this and is connected to T6 'by the control signal from the switching circuit. A voltage level is output so that the operation of the high frequency amplifier circuit as shown in FIG. 3 is stopped.

〔The invention's effect〕

As described above, according to the present invention, the semiconductor integrated circuit 12
By controlling the high-frequency amplifier circuit for the AM and FM connected externally to the receiver, which is unnecessary for the function of the receiver, the high-frequency amplifier circuit for the AM / FM receiver can reduce the total power consumption.

[Brief description of drawings]

1 is a principle diagram of the present invention, FIG. 2 is a conventional example of an AM / FM receiver, FIG. 3 is an embodiment of a high frequency amplifier circuit shown in FIG. 1, and FIG. 4 is a semiconductor integrated circuit shown in FIG. An embodiment of the circuit 12, especially for the switching circuit, is shown. 1 ... AM receiving antenna, 2 ... AM high-frequency amplifier circuit, 3 ...
FM receiving antenna, 4 ... FM high frequency amplifier circuit, 5 ... AM intermediate frequency section, 6 ... AM intermediate frequency signal processing circuit, 7 ... AM gain control circuit, 8 ... FM intermediate frequency section, 9 ... FM intermediate frequency signal processing Circuit, 10 ... FM gain control circuit, 11 ... Switching circuit, 12 ... Semiconductor integrated circuit, 13 ... Rectifier circuit, T1 ... AM receiver output terminal, T2 ... FM
Receiver output terminal, T3 ... Switching circuit control signal input terminal, T4
… Power supply terminal, T5… Received signal input terminal, T6, T6 ′… Control signal output terminal, T7… High frequency amplifier output terminal, T8… Reference voltage terminal, Q1, Q2, Q3, Q4, Q5, Q6, Q7… Transistor, R1, R
2, R3, R4, R5 ... Resistor, C1, C2 ... Capacitor, L1 ... Inductor, l _O ... Current source

Claims (1)

[Claims] 1. An AM high-frequency amplifier circuit in which an AM intermediate-frequency signal processing circuit and an FM intermediate-frequency signal processing circuit are formed on the same semiconductor substrate, and which is connected to the outside of the semiconductor substrate at the preceding stage of the AM intermediate-frequency signal processing circuit. And an AM / FM equipped with a high-frequency amplifier circuit for FM connected to the preceding stage of the FM intermediate-frequency signal processing circuit
In the receiver, the AM intermediate frequency signal processing circuit and AM
A gain control circuit for controlling the gain of the high frequency amplification circuit for FM, and an FM gain control circuit for controlling the gain of the FM intermediate frequency signal processing circuit and the high frequency amplification circuit for FM. Control signal of, not the receiving side
The AM gain control circuit or FM gain control circuit is controlled, and the output of the controlled AM or FM gain control circuit causes the AM
Alternatively, an AM / FM receiver characterized by stopping the operation of the high frequency amplifier circuit for FM.