JPS5918758Y2 - External circuit connection device for multifunctional integrated circuits - Google Patents

Description

[Detailed explanation of the invention] By highly integrating circuits that are currently constructed using independently manufactured parts, it is possible to replace the entire circuit or multiple functional parts with a single integrated circuit. is being carried out.

Therefore, the more functions built into the circuit, the more the integrated circuit can be unified.

However, among such multi-functional and highly integrated circuits, there is a tuner integrated circuit, which has a high degree of completeness but has the disadvantage that its degree of freedom is reduced.

In other words, if a certain part of the integrated circuit, such as an intermediate frequency amplification circuit or a detection circuit, does not meet the target specifications, the integrated circuit We had no choice but to abandon the entire recruitment process.

In particular, characteristic deterioration of the S/N ratio and distortion rate in the detection circuit is fatal for FM tuners, and when such a situation occurs, it is necessary to adopt it in another integrated circuit, or to change the main signal system and control system. Measures were taken to configure each independently.

This idea is to enable the use of such an integrated circuit by having an external circuit take over the operation of that part when the detection circuit that determines the performance of the tuner cannot meet the target specifications in such a tuner integrated circuit. An embodiment of this invention will be described below with reference to the drawings.

That is, this embodiment shows an FM tuner in which an intermediate frequency amplification circuit, a detection circuit, a signal control circuit, and an instruction circuit are integrated.

In FIG. 1, 1 and 2 are intermediate frequency amplifier circuits, 3 is a detection circuit, 4 is a signal level detection circuit, 5 is a muting circuit, and 6 is a tuning instruction circuit.

Assume that in this integrated circuit, the S/N ratio or distortion rate of the detection circuit 3 does not satisfy the target.

That is, if the specifications of the circuits other than this detection circuit are satisfied, as shown in Fig. 2, the signal is taken out from the input side of the detection circuit 3, and it is separated into a signal with a satisfactory S/N ratio or distortion factor. The main signal, for example, an audio signal, is used as an input to the configured external detection circuit 7, and the detection circuit 3, which is configured as an old product circuit, requires a particularly high S/N ratio and distortion rate, for example, as a muting or tuning instruction circuit. Used for control signals for circuit parts that are not used.

FIG. 3 is a concrete example of the block diagram shown in FIGS. 1 and 2, and parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals.

In addition, the part surrounded by the dashed-dotted line in the figure is integrated.

In this figure, numeral 31 constitutes a part of the detection circuit 3.

Ll is an inductance coil connected between terminals 8 and 9 of integrated circuit A. Although it is desirable to accommodate this within integrated circuit A as much as possible, due to its shape, it is unavoidable to install it outside of it. It will be done.

Further, a parallel circuit of an inductance coil L2 and a capacitor C2 is connected between terminals 9 and 10.

Furthermore, a center meter M1 is connected between terminals 10 and 7, and one end of this meter is connected to one end of a parallel circuit of coils L2 and C2.

R is the protection resistance of the center meter.

7 is an external detection circuit, which is connected to one end of the coil L1 (terminal 8 of the integrated circuit A) via a capacitor C1.

That is, since a part of the signal supplied from the intermediate frequency amplification circuit 1.2 to the detection circuit 3 is superimposed on the terminal 8, by inputting this signal to the external detection circuit 8, the main signal is output from this detection circuit. This is to extract the signal output.

As mentioned above, this idea replaces the function of the detection circuit in the tuner integrated circuit that does not meet the target specifications with an externally connected circuit that has the same function but has good specifications. It can be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of this invention, FIG. 2 is a block diagram of the main part, and FIG. 3 is a circuit diagram showing a specific example.

Claims (1)

[Scope of utility model registration request] An external detection circuit is connected to the intermediate frequency amplifier circuit output terminal of the integrated circuit constituting at least the intermediate frequency amplifier circuit, the detection circuit, the muting circuit, and the tuning instruction circuit, and when the characteristics of the detection circuit in the integrated circuit are not satisfied, the external detection circuit is connected. External circuit connection of a tuner integrated circuit, characterized in that a detection output of a main signal is obtained from a detection circuit, and a signal from the detection circuit in the integrated circuit is used as a control signal for the muting circuit or tuning instruction circuit. Device.