WO2009004933A1

WO2009004933A1 - Am/fm radio receiver and receiving semiconductor integrated circuit used for same

Info

Publication number: WO2009004933A1
Application number: PCT/JP2008/061280
Authority: WO
Inventors: Takeshi Ikeda; Hiroshi Miyagi
Original assignee: Nsc Co., Ltd.
Priority date: 2007-07-05
Filing date: 2008-06-13
Publication date: 2009-01-08
Also published as: JP2009017286A

Abstract

The first-stage amplifier of an AM receiver circuit and the first-stage amplifier of an FM receiver circuit are contained in an IC (2) as differential amplifier circuits (3, 4). The AM differential amplifier circuit (3) is connected to a first pad (P1) connected to the duplex antenna for AM/FM. An FM separation capacitor (C1) and the FM differential amplifier circuit (4) are connected parallel to the AM differential amplifier circuit (3). Consequently, a pad capacitor (Cp) is formed between the first pad (P1) and the board, and allowed to function as a capacitor for absorbing only the signal in the FM frequency band and passing the signalin the AM frequency band. Therefore, the AM separation coil which has been conventionally an external component is made unnecessary.

Description

AM Z F M radio receiver and receiving semiconductor integrated circuit used therefor

Technical field

The present invention relates to a radio receiver capable of receiving both an AM radio wave and an FM radio wave, and a receiving semiconductor integrated circuit used for the radio receiver.

And FM signal to the FM receiver circuit and FM signal to the AM receiver circuit.

Rice field 1

This relates to radio receivers that are not mixed.

Background art

Conventionally, in-vehicle AM Z FM radio receivers that can receive both AM radio waves and FM radio waves have been made so that AM radio waves and FM radio waves can be received by a common antenna element. When receiving AM radio waves and FM radio waves using a shared antenna, it is necessary to prevent AM radio signals from interfering with FM receiver circuits and FM radio signals from interfering with AM receiver circuits. For this purpose, an AM separation circuit for separating an AM signal and an FM separation circuit for separating an FM signal are connected to the base end of the antenna element (for example, see Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 8 — 1 1 6 2 8 4

Fig. 1 is a circuit diagram showing the configuration of the tuner section of a conventional AMZ FM radio receiver that can receive AM radio waves and FM radio waves with a shared antenna. In Fig. 1, the radio wave received by the common antenna 1 1 for AM radio waves and FM radio waves is sent to the AM radio wave (AM frequency band signal) and FM radio wave (by the coil L 1 1 and capacitor C 1 1). FM frequency band signal). The coil LI 1 is an AM separating coil in which an inductor is set so that signals in the AM frequency band can pass but signals in the FM frequency band can be blocked. That is, the coil L 1 1 acts as a low impedance for the AM frequency band and allows signals in the AM frequency band to pass. On the other hand, it acts as a high impedance for the FM frequency band and blocks the passage of signals in the FM frequency band.

Capacitor C I 1 is a capacitor for FM separation whose capacitance is set so that signals in the FM frequency band can pass but signals in the AM frequency band can be blocked. That is, the capacitor C 1 1 acts as a high impedance for a low AM frequency band, and blocks the passage of signals in the AM frequency band. On the other hand, it acts as a low impedance for the high frequency band of FM and allows the FM frequency band signal to pass.

The AM signal separated by the coil L I 1 is supplied to the AM receiving circuit 12. In the AM receiver circuit 1 2, the AM signal that has passed through the bypass capacitor C is fed by a first-stage amplifier composed of a junction field effect transistor (junction FET) or a MO S transistor (MO SFET) Tr 1 1. The amplified AM signal is output to the mixer unit 13 at the next stage via the bipolar transistor T r 1 2.

On the other hand, the FM signal separated by the capacitor C 11 is supplied to the FM receiver circuit 14. In the FM receiver circuit 14, only the FM signal of a specific frequency is amplified in the FM tuning circuit 15 composed of the coil L 1 2 and the variable capacitance diode (paractor) D 1 1. Next, the FM signal is amplified by the first-stage amplifier composed of two cascode-connected FET transistors T r 1 3 and T r 14, and the amplified FM signal is converted into the mixer section at the next stage. 1 Output to 6.

AM signal mixer section 1 3 and later circuits (not shown) and FM signal Both the circuits after the mixer section 16 (not shown) are integrated on a semiconductor chip (IC) 20 by a CMO S (Complementary Metal Oxide Semiconductor) process. On the other hand, the coil L 1 1 for AM separation, the capacitor C 1 1 for FM separation, the AM receiver circuit 1 2 and the FM receiver circuit 14 are

It is configured as an external part of I C 20.

The transistor T r 1 2 of the AM receiver circuit 1 2 is generally composed of bipolar transistors that are easy to match. AM receiver circuit

1 2 transistor T r 1 1 and FM receiver circuit 1 4 transistors T r 1 3, T r 1 4 generally have a large input impedance and input capacitance S / J, junction type It is configured using a field effect transistor. Both bipolar and junction field effect transistors are C

It is difficult to integrate on the same IC20 as the MOS transistor of the MOS process, so they are configured as external parts of IC20.

Further, the coil L 11 and the capacitor C 11 are provided in front of the AM receiving circuit 12 and FM receiving circuit 14 which are external parts. For this reason

It is physically difficult to integrate the coil L 1 1 and the capacitor C 1 1 on the IC 20. Also, the coil L 1 1 is a high impedance element for the FM frequency band. I to act as a sea urchin, since the inductor data is necessary force ^s to greatly, it is technically and flame arbitrary to integrate into IC 2 0 above. Therefore, the reel L 11 and the capacitor C 11 are closed as external components of the IC 20. Disclosure of the invention

However, the above conventional technique has a problem that the number of external parts of I c is large, which is an obstacle to downsizing the radio receiver. Book The invention has been made to solve such problems, and in an AMZF M radio receiver configured to be able to receive AM radio waves and FM radio waves with a shared antenna, an external component of the IC is provided. The purpose is to reduce the number of points so that the size can be reduced.

In order to solve the above-described problems, in the present invention, the AM amplifier first-stage amplifier and the FM receiver first-stage amplifier are each incorporated as a differential amplifier circuit in an integrated circuit, and the AMZ FM shared antenna is connected. An AM differential amplifier circuit is connected to one pad of the integrated circuit, and an FM isolation capacitor and FM differential amplifier circuit are connected in parallel with the AM differential amplifier circuit. Connected.

According to the present invention configured as described above, the AM differential amplifier circuit and the FM differential amplifier circuit can be configured by the MOS transistor, which is conventionally an external component of the IC. The first amplifier of the AM receiver circuit and the first amplifier of the FM receiver circuit can be integrated in the IC. On the IC of the CMOS process, the capacitance (hereinafter referred to as pad capacitance) formed between one pad to which the AM differential amplifier circuit is connected and the substrate is reduced. For this reason, the pad capacity acts as a capacity that absorbs only the FM frequency band signal and allows the AM frequency band signal to pass therethrough. This eliminates the need for an AM separation coil that was previously an external component. As a result, the number of external parts of I C is significantly reduced, and the A M F M radio receiver can be downsized. Brief Description of Drawings

FIG. 1 is a diagram illustrating a configuration example of a tuner unit of a conventional AM / FM radio receiver.

Figure 2 shows AMZFM using the semiconductor integrated circuit for reception according to the present embodiment. It is a figure which shows the structural example of the tuner part of a radio receiver. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a circuit diagram showing a configuration example of the tuner unit of the AMZFM radio receiver using the receiving semiconductor integrated circuit according to the present embodiment. As shown in FIG. 2, the AMZFM radio receiver of this embodiment includes a common antenna 1 that receives AM radio waves and FM radio waves, and a receiving semiconductor integrated circuit (to which the common antenna 1 is connected) ( IC) 2. I C 2 is a semiconductor chip composed of the CMO S process.

In the configuration of I C 2, P 1, P 2 and P 3 are nodes.

In the first pad P 1 (corresponding to one pad of the present invention), the shared antenna 1 is connected to the outside of the IC 2. The second and third packs K P 2,

P 3 (corresponding to another pad of the present invention) This is a coil constituting the “−” part of the FM tuning circuit 5, and is connected to the outside of the L 2 force S IC 2, and the FM tuning circuit

A variable capacitance diode D 1 (corresponding to the variable capacitance circuit of the present invention) constituting a part of 5 is connected to the internal side of I C 2.

Here, the variable capacitance diode 'D 1 is used as an example of the variable capacitance circuit, but is not limited to this. For example, a variable capacitance * circuit may be configured by a plurality of capacitors having different capacitance values and a switch for selecting one of the plurality of capacitors.

Further, in the IC 2, the AM differential amplifier circuit 3 is connected to the first pad P 1. The AM differential amplifier circuit 3 differentially amplifies the AM frequency band signal received by the shared antenna 1. This AM differential amplifier circuit 3 includes four p MOS transistors M1 to M4. M l and M 2 constitute an input differential amplifier, and the AM radio signal received by the shared antenna 1 is input to one of the p MO S transistors M l, and the other p MO S transistor A signal of bias voltage V _{B 1} is input to M2. M 3 and M 4 form a differential amplifier, and a signal of bias voltage V _{B 2} is input to both p MO S transistors M 3 and M 4. The AM signal amplified by the AM differential amplifier circuit 3 is output to the AM mixer unit 6 at the next stage.

A pad capacitance C p having a small capacitance value is formed between the first pad P 1 to which the AM differential amplifier circuit 3 is connected and the substrate (ground). This pad capacitance C _P functions as a capacitance that absorbs only signals in the FM frequency band. That is, pad capacitance C p is to act as a high Npi dance for low frequency bands of AM, signal AM frequency band does not flow to the pad capacitance C _P Karagu run mode. On the other hand, the pad capacitance C _P acts as a low impedance for the high frequency band of FM and shorts it to the ground. Do not supply to the dynamic amplification circuit 3.

Capacitors C 2 and C 3 serving as a low-pass filter are connected to the two differential output lines connected from the AM differential amplifier circuit 3 to the AM mixer section 6. Of the above-mentioned good sea urchin, but the pad capacitance C _P to absorb the signal of the FM frequency band, is also conceivable that which can not be completely absorbed. The low-pass filter consisting of capacitors C 2 and C 3 is set to have a frequency characteristic that cuts off the FM frequency band (attenuates the signal abruptly above the AM frequency band). By providing such capacitors C 2 and C 3, it is possible to more reliably suppress FM signal interference to the AM receiver circuit.

Further, a high-pass filter including a resistor R a and a capacitor C a is connected to the input differential pair M l and M 2 of the AM differential amplifier circuit 3. This The high-pass filter has a frequency characteristic that cuts off a low-frequency region of 50 to 60 Hz or lower. This high-pass filter functions as a hum removal filter for removing hum caused by electromagnetic induction due to the earth potential difference. Although not shown in Fig. 1, in the conventional radio receiver, a coil having a large inductance such as several mH to 50 mH had to be connected to the antenna 11 in order to remove hum. On the other hand, in the present embodiment, it is possible to remove the ham without any external components only by forming a high-pass filter including the resistor Ra and the capacitor Ca in the IC 2.

An FM separation capacitor C 1 is also connected to the first pad P 1 of I C 2 in parallel with the AM differential amplifier circuit 3. The FM separation capacitor C 1 is an FM separation capacitor whose capacitance is set so that signals in the FM frequency band can pass but signals in the AM frequency band can be blocked. In other words, the FM separation capacitor C 1 acts as a high impedance for the AM frequency band and blocks the passage of signals in the AM frequency band. On the other hand, it acts as a low impedance for the FM frequency band and allows signals in the FM frequency band to pass.

The FM differential amplifier circuit 4 and the FM tuning circuit 5 are connected to the subsequent stage of the FM isolation capacitor C 1. The FM tuning circuit 5 is composed of a variable capacitance diode D 1 integrated inside I C 2 and a coil L 2 connected as an external component outside I C 2. The FM signal separated by the FM separation capacitor C 1 is amplified in the FM tuning circuit 5 only by the FM signal having a specific frequency, and is output to the FM differential amplification circuit 4.

The FM differential amplifier circuit 4 amplifies the FM frequency band signal received by the shared antenna 1 and passed through the FM separation capacitor C 1. This FM differential amplifier circuit 4 is composed of four n MOS transistors M5 to M8. It is.

M 5 and Μ 6 constitute an input differential amplifier, and an FM radio signal received by the shared antenna 1 and passed through the FM separation capacitor C 1 is input to one of the n MO S transistors M 5 . Signal of the bias voltage V _{B 4} is input to the p MO S transistor motor M 6 of one cormorants also. M 7 and M 8 constitute a differential pair, and a signal of bias voltage V _{B 3} is input to both nMOS transistors M 7 and M 8. The FM signal amplified by the FM differential amplifier circuit 4 is output to the FM mixer section 7 in the next stage.

As described above in detail, in this embodiment, the first amplifier of the AM receiver circuit and the first amplifier of the FM receiver circuit are integrated into the IC 2 as differential amplifier circuits 3 and 4, respectively. The AM differential amplifier circuit 3 is connected to the first pad P 1 to which the shared antenna 1 is connected, and the FM differential capacitor C is connected in parallel with the AM differential amplifier circuit 3. 1 and FM differential amplifier circuit 4 were connected.

According to the AMZFM radio receiver of the present embodiment configured as described above, the AM differential amplifier circuit 3 and the FM differential amplifier circuit 4 are converted into MOS transistors in the same manner as the circuits after the mixer sections 6 and 7. It can be configured more. For this reason, the AM amplifier circuit first stage amplifier and FM receiver circuit first stage amplifier, which were formerly external components of IC 20 as shown in Fig. 1, are integrated into IC 2. as shown in Fig. 2. You can.

On the CMOS process IC 2, a pad capacitance C _P having a small capacitance value is provided between the first pad P 1 to which the AM differential amplifier circuit 3 is connected and the substrate (ground). It is formed. This pad capacitance C _P functions as a capacitance that absorbs only signals in the FM frequency band. This eliminates the need for the AM separation coil L 11, which was previously an external component as shown in FIG.

From the above, according to the AMZFM radio receiver of this embodiment, In comparison, the number of external components of IC 2 is significantly reduced. That is, as shown in FIG. 2, the external components of IC 2 are only the common antenna 1 and the coil L 2 of the FM tuning circuit 5. Therefore, most circuits can be integrated in IC 2 to reduce the size of the AMZ FM radio receiver.

The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereby. . That is, the present invention can be implemented in various forms without departing from the spirit or the main features thereof. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention is useful for an AMZFM radio receiver, for example, an in-vehicle radio receiver, in which an AM radio signal is not mixed into the FM receiver circuit and an FM radio signal is not mixed into the AM receiver circuit. .

Claims

1. AM radio ops FM A shared antenna that receives FM radio waves, and a receiving semiconductor integrated circuit to which the shared antenna is connected,

The receiving semiconductor integrated circuit has one pad to which the shared antenna is connected, and α blue

An AM differential amplifier circuit that is connected to the one pad and amplifies the AM radio wave received by the shared antenna;

Of 1

A car connected in parallel with the AM differential amplifier circuit from the one pad above.

A high-impedance range for the AM frequency band

For the FM frequency band, an FM isolation capacitor that acts as a low impedance,

An AM / FM radio comprising an FM differential amplifier circuit that is connected to the FM separation capacitor and is received by the shared antenna and that amplifies the FM radio wave that has passed through the FM separation capacitor. Receiving machine.

2. The receiving semiconductor integrated circuit further includes a variable capacitance circuit for an FM tuning circuit connected to the FM isolation capacitor,

The variable capacitance circuit includes a coil for the FM tuning circuit connected to the outside of the receiving semiconductor integrated circuit via another pad different from the one pad. The AM ZFM radio receiver according to claim 1.

3. AM radio and one pad to which a shared antenna that receives FM radio is connected,

A controller connected in parallel with the AM differential amplifier circuit from the one pad. An FM isolation capacitor that acts as a high impedance for the AM frequency band and acts as a low impedance for the FM frequency band;

A receiving semiconductor integrated circuit comprising: an FM differential amplifier circuit that amplifies the FM radio wave that is connected to the FM separation capacitor, received by the shared antenna, and passed through the FM separation capacitor.

4. The receiving semiconductor integrated circuit according to claim 3, wherein the AM differential amplifying circuit and the FM differential amplifying circuit are configured by a MOS transistor.