JPH0336121Y2 - - Google Patents

Description

[Detailed description of the invention] This idea relates to a grounding circuit for a receiver, and its feature is that the grounding line of a circuit in which both high-frequency current and low-frequency current exist is connected via a capacitor, respectively. By connecting to the nearest ground point of the chassis and commonly connecting to the low frequency ground point of the chassis via an inductor,
For high-frequency currents, use the shortest multi-point grounding method.
Furthermore, low frequency current can be grounded at one point, resulting in improved S/N ratio and significantly improved sound quality.

Generally, in high frequency circuits, it is desirable to ground each amplifier stage at the shortest possible distance.
In contrast to multi-point grounding as shown in Figure 1A, in low frequency circuits it is common to use a single point grounding as shown in Figure 1B to prevent loop effects. It is.

However, in devices such as receivers that have both high-frequency circuits and low-frequency circuits, if the high-frequency circuit is grounded at multiple points, the signal current, including the power supply current, will flow through the chassis and return to the power supply. In some cases, the S/N ratio deteriorates due to the ripple component of the power supply, or a loop is created, resulting in induced hum.

The purpose of this invention is to improve the drawbacks of the conventional devices described above, by providing a grounding circuit that provides multi-point grounding for high-frequency currents and one-point grounding for low-frequency currents. be.

An embodiment of this invention will be described with reference to FIG.

Tuner's high frequency amplification section RF1 and detection section RF
2 ground lines are connected to the nearest ground points 1a and 1c of the chassis 1 through capacitors C for each stage, and are also connected to a common low frequency ground point 1d through coils L. There is.

An LC filter is provided between each high frequency stage RF1 and RF2 and the power supply 3 to prevent feedback.

The ground line of the antenna input terminal 2 is connected via a capacitor C to the nearest ground point 1a, and via a coil L to a common low frequency ground point 1d.

The demodulator AF and output terminal 4, through which only low frequency current flows, are connected directly to the common low frequency ground point 1.
connected to d.

High frequency amplifier section RF1, detection section RF2 and demodulator
The AF signal transmission paths are each coupled by a capacitor C'.

With this configuration, the high frequency current of each circuit is grounded via the capacitor C at the shortest distance in each stage, and the low frequency current is common to the low frequency ground point via the coil L. Grounded.

In other words, multi-point grounding is used for high-frequency currents, and one-point grounding is used for low-frequency currents, so the high-frequency currents are separated from the power supply and low-frequency currents, and the S/N ratio due to the ripple component of the power supply is reduced. It is possible to prevent deterioration and feedback of the output signal to the input.

FIG. 3 shows a case in which the present invention is implemented in the input terminal section 2 of a receiver using a loop antenna.

In front of the capacitor Co provided between the input circuit, the ground line is connected to the nearest ground point of the chassis 1 via the capacitor C, and is also connected to the common low frequency ground point 1d via the coil L. The operation and effect are the same as those of the previous embodiment. In addition, in the above example,
Although a configuration including a capacitor C and a coil L is shown, it goes without saying that the configuration may be configured using other capacitors and inductors.

As explained above, the grounding circuit of the receiver, etc. of this invention connects the grounding line of the circuit in which both high-frequency current and low-frequency current exist to the nearest grounding point of the chassis via a capacitor, respectively. By commonly connecting to the low-frequency ground point of the chassis via an inductor, it is possible to provide multi-point grounding with the shortest distance for high-frequency currents, and one-point grounding for low-frequency currents. is possible,
This improves the S/N ratio and significantly improves the sound quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is a block diagram of one embodiment of this invention, and FIG. 3 is a plan view of another embodiment. 1...Shade, 1a, 1b, 1c...Earth point, 1d...Low frequency earth point, 2...
Antenna input terminal, 3...power supply, 4...output terminal.

Claims (1)

[Scope of utility model registration request] Connect the ground lines of the circuits in which both high-frequency current and low-frequency current exist to the nearest ground point of the chassis through capacitors, and
A grounding circuit for a receiver, etc., characterized in that each of the grounding points is commonly connected to a low frequency grounding point of a chassis via an inductor.