JP5075716B2 - Semiconductor integrated circuit device - Google Patents

Description

  The present invention relates to a semiconductor integrated circuit device, and more particularly to a semiconductor integrated circuit device including an amplifier including an electrostatic protection circuit.

  Oscillation circuits using solid-state vibrators such as crystal vibrators and ceramic vibrators are widely used in various electronic devices. The oscillation circuit is often constituted by an inverting amplifier or a differential amplifier in which a solid oscillator is connected in parallel with a bias resistor in a feedback path.

  For example, Patent Document 1 describes a Colpitts-type crystal oscillation circuit that feeds back from a reverse-phase output of a differential amplifier to an in-phase input via a crystal resonator. This circuit inputs the NRZ reception data change point detection pulse signal to the negative phase input of the differential amplifier, and extracts the timing signal that is phase-synchronized with the NRZ reception data change point detection pulse signal from the in-phase output of the differential amplifier. It functions as a timing extraction circuit using an oscillator.

  Patent Document 2 discloses an oscillation circuit that includes a protection circuit at each input / output terminal of an inverting amplifier, and further includes a capacitor between the input terminal of the inverting amplifier and the protection circuit. This circuit prevents a leak current flowing into or out of the input terminal from the protection circuit by the capacitive element.

JP 60-165850 A US Pat. No. 6,320,473

  The following analysis is given in the present invention.

  When an oscillation circuit using a solid vibrator is mounted on a semiconductor integrated circuit device, an external terminal is provided in the semiconductor integrated circuit device, and the solid vibrator is connected to the external terminal. In the semiconductor integrated circuit device, the external terminal is exposed to the outside, and thus is affected by the outside. Especially, the influence due to static electricity sometimes damages the semiconductor integrated circuit device. Therefore, it is common to provide an electrostatic protection circuit connected to the external terminal inside the semiconductor integrated circuit device so as to prevent damage to the semiconductor integrated circuit device when static electricity is applied to the external terminal.

  By the way, in recent years, with the fine patterning of semiconductor integrated circuit devices, the power supply voltage of semiconductor integrated circuit devices has been reduced, and the threshold value of devices has been lowered. For this reason, the leakage current in the input / output protection circuit is increased, and it is not rare that the value of the leakage current becomes several μA.

  On the other hand, the value of the bias resistor connected in parallel with the solid-state vibrator between the input and output of the inverting amplifier or the differential amplifier is very high, and is usually from several hundred Ω to 1 MΩ in some cases. Therefore, especially when the leakage current increases at a high temperature, the bias point at the input end of the amplifier shifts, the oscillation waveform is distorted, and sometimes the oscillation stops.

  By the way, in the oscillation circuit described in Patent Document 2, leakage current is blocked by a capacitive element provided between the input terminal and the protection circuit. However, when the oscillation circuit is configured in a semiconductor integrated circuit device, the capacitive element occupies a large area. Therefore, when the capacitive element is mounted in the semiconductor integrated circuit device, the semiconductor integrated circuit device may be increased in size.

  The inventor of the present invention has come up with a configuration that stably oscillates even when the number of leakage current blocking capacitance elements is reduced.

A semiconductor integrated circuit device according to one aspect (side surface) of the present invention includes a first external terminal capable of connecting one end of an external circuit, a second external terminal capable of connecting the other end of the external circuit, The first resistance element, the second resistance element, the inverting input terminal are connected to the first external terminal and one end of the first resistance element, and the output terminal is connected to the second external terminal and the first resistance element. A differential amplifier connected to the other end and connecting a non-inverting input terminal to a bias supply source via a second resistance element, a first electrostatic protection circuit connected to the inverting input terminal, and a non-inverting input terminal A differential electrostatic amplifier further comprising an inverting output terminal, configured to output an output signal from the inverting output terminal to the internal circuit, and inverting the bias supply source It shall be the output terminal.
A semiconductor integrated circuit device according to another aspect (side surface) of the present invention includes a first external terminal capable of connecting one end of an external circuit, a second external terminal capable of connecting the other end of the external circuit, The first resistance element, the second resistance element, the inverting input terminal are connected to the first external terminal and one end of the first resistance element, and the output terminal is connected to the second external terminal and the first resistance element. A differential amplifier connected to the other end and connecting a non-inverting input terminal to a bias supply source via a second resistance element, a first electrostatic protection circuit connected to the inverting input terminal, and a non-inverting input terminal A second electrostatic protection circuit connected to the first resistance element, and the bias supply source is a predetermined division point of the first resistance element.

  According to the present invention, when the leakage current in the electrostatic protection circuit increases, the bias voltages of the inverting input terminal and the non-inverting input terminal both fluctuate in the same direction, and the fluctuation of the DC voltage at the output of the differential amplifier is suppressed. be able to. Therefore, an oscillation circuit having a small circuit scale that stably oscillates in a wide temperature range is configured.

  A semiconductor integrated circuit device according to an embodiment of the present invention includes a first external terminal capable of connecting one end of an external circuit, a second external terminal capable of connecting the other end of the external circuit, and a first resistor. The element, the second resistance element, and the inverting input terminal are connected to the first external terminal and one end of the first resistance element, and the output terminal is connected to the second external terminal and the other end of the first resistance element. And a differential amplifier that connects the non-inverting input terminal to the bias supply source via the second resistance element, a first electrostatic protection circuit that is connected to the inverting input terminal, and a non-inverting input terminal. A second electrostatic protection circuit.

  In the semiconductor integrated circuit device according to the embodiment of the present invention, the differential amplifier may further include an inverting output terminal and output an output signal from the inverting output terminal to the internal circuit.

  In the semiconductor integrated circuit device according to the embodiment of the present invention, the bias supply source may be an inverting output terminal.

  In the semiconductor integrated circuit device according to the embodiment of the present invention, the bias supply source may be a predetermined division point of the first resistance element.

  The semiconductor integrated circuit device according to the embodiment of the present invention may further include a third electrostatic protection circuit connected to the output terminal.

  In the semiconductor integrated circuit device according to the embodiment of the present invention, the external circuit is a circuit including a solid-state vibrator and preferably functions as an oscillation circuit.

  Hereinafter, it will be described in detail with reference to the drawings in accordance with embodiments.

  FIG. 1 is a circuit diagram of a semiconductor integrated circuit device according to a first embodiment of the present invention. In FIG. 1, a semiconductor integrated circuit device 10 includes a differential amplifier OP, resistance elements R1 and R2, external terminals P1 and P2, and electrostatic protection circuits 11a, 11b, and 11c. In the differential amplifier OP, the inverting input terminal (−) is connected to the external terminal P1, one end of the resistor element R1, and the electrostatic protection circuit 11b, and the output terminal is connected to the external terminal P2, the other end of the resistor element R1, and the electrostatic protection circuit. 11c, and the non-inverting input terminal (+) is connected to the electrostatic protection circuit 11a and to the inverting output terminal via the resistance element R2. In this case, it is preferable to make the resistance values of the resistance elements R1 and R2 equal. The electrostatic protection circuits 11a, 11b, and 11c, for example, connect two diodes connected in series in the reverse direction between the power source and the ground, and connect the connection point of the two diodes to the non-inverting input terminal ( +), An inverting input terminal (−), and an output terminal.

  Further, the semiconductor integrated circuit device 10 externally connects both ends of the crystal resonator XTL between the external terminals P1 and P2, and connects the other end of the capacitive element C1 whose one end is grounded to the external terminal P1. The other end of the capacitive element C2 whose one end is grounded is connected to P2 to constitute an oscillation circuit. Further, the output OUT from the oscillation circuit is given to the internal circuit of the semiconductor integrated circuit device 10 (not shown) from the inverting output terminal of the differential amplifier OP. This inverted output terminal is not connected to the outside of the semiconductor integrated circuit device. Capacitance elements C1 and C2 may be mounted inside the semiconductor integrated circuit device as necessary.

  In the semiconductor integrated circuit device 10 having such a configuration, it is assumed that a leakage current is generated in the electrostatic protection circuit. Here, a leakage current flowing from the power supply side to the resistance element R1 via the electrostatic protection circuit 11b is I1, and a leakage current flowing from the power supply side to the resistance element R2 via the electrostatic protection circuit 11a is I2. Since the electrostatic protection circuits 11a and 11b are in the semiconductor integrated circuit device 10 and manufactured by the same process, they are equivalent and have the same leakage currents I1 and I2. Further, the DC potentials of the output terminal and the inverted output terminal of the differential amplifier OP are equal. Therefore, by making the resistance values of the resistance elements R1 and R2 equal, the potential fluctuations due to the leakage currents of the inverting input terminal (−) and the non-inverting input terminal (+) of the differential amplifier OP become equal. That is, even when the leakage currents I1 and I2 increase due to a temperature rise or the like, the potential increases at the inverting input terminal (−) and the non-inverting input terminal (+) are equal, and the output terminal and the inverting terminal of the differential amplifier OP are inverted. It is possible to prevent fluctuations in the DC potential of the output terminal. For this reason, the semiconductor integrated circuit device 10 can perform a stable oscillation operation over a wide temperature range. The leakage current also flows through the electrostatic protection circuit 11c. However, since the impedance at the output terminal of the differential amplifier OP is low, the potential at the output terminal does not fluctuate due to the leakage current flowing through the electrostatic protection circuit 11c.

  In the above description, the leak current has been described as flowing from the power source side. On the other hand, even when a leak current flows out to the ground side, the potential drops at the inverting input terminal (−) and the non-inverting input terminal (+) are equal, and similarly, the DC power of the output terminal and the inverting output terminal of the differential amplifier OP. The fluctuation of the position can be prevented.

  Further, the inverting output terminal of the differential amplifier OP is not directly output as a terminal outside the semiconductor integrated circuit device 10. Therefore, even if it is used in a place with a lot of environmental noise, the influence of noise on the internal circuit can be extremely reduced. Of course, noise that can be input from the external terminal P1 is amplified by the differential amplifier OP. However, the upper limit of the frequency of the differential amplifier OP is 1 to 2 orders of magnitude lower than that of a general oscillation circuit constituted by a single-ended circuit.

  FIG. 2 is a circuit diagram of a semiconductor integrated circuit device according to the second embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 represent the same items, and the description thereof is omitted. The semiconductor integrated circuit device 10a of FIG. 2 divides the resistance element R1 of FIG. 1 into two series-connected resistance elements R3 and R4, and the resistance element R5 corresponding to the resistance element R1 is a non-inversion of the differential amplifier OP. It connects between an input terminal (+) and the connection point of resistive element R3, R4. In this case, it is preferable to make the resistance values of the resistance elements R3 and R5 equal.

  In the semiconductor integrated circuit device 10a having such a configuration, it is assumed that a leakage current is generated in the electrostatic protection circuit as in the first embodiment. Here, the value of the leakage current flowing from the power supply side to the resistance element R3 via the electrostatic protection circuit 11b is equal to the value of the leakage current flowing from the power supply side to the resistance element R5 via the electrostatic protection circuit 11a. Therefore, by making the resistance values of the resistance elements R3 and R5 equal, the potential fluctuations due to the leakage current at the inverting input terminal (−) and the non-inverting input terminal (+) of the differential amplifier OP become equal. Therefore, similarly to the first embodiment, the semiconductor integrated circuit device 10a can perform a stable oscillation operation.

  FIG. 3 is a circuit diagram of a semiconductor integrated circuit device according to the third embodiment of the present invention. 3, the same reference numerals as those in FIG. 1 represent the same items, and the description thereof is omitted. A semiconductor integrated circuit device 10b of FIG. 3 includes a differential amplifier OPa in which an inverting output terminal is omitted instead of the differential amplifier OP, and an output terminal is connected to an internal circuit of the semiconductor integrated circuit device 10a as an output OUT. A resistance element R6 corresponding to the resistance element R1 is connected between the non-inverting input terminal (+) of the differential amplifier OPa and the bias supply source Vb. In this case, it is preferable that the resistance values of the resistance elements R1 and R6 are equal, and the potential of the bias supply source Vb is equal to the DC potential (amplitude center potential) of the output terminal of the differential amplifier OPa.

  In the semiconductor integrated circuit device 10b having such a configuration, it is assumed that a leakage current is generated in the electrostatic protection circuit as in the first embodiment. Here, the value of the leakage current flowing from the power supply side to the resistance element R1 via the electrostatic protection circuit 11b is equal to the value of the leakage current flowing from the power supply side to the resistance element R6 via the electrostatic protection circuit 11a. Therefore, the resistance values of the resistance elements R1 and R6 are made equal, and the potential of the bias supply source Vb is made equal to the direct current potential (amplitude center potential) of the output terminal of the differential amplifier OPa, whereby the inverting input of the differential amplifier OPa. The potential fluctuations due to the leakage current at the terminal (−) and the non-inverting input terminal (+) become equal. Therefore, like the first embodiment, the semiconductor integrated circuit device 10b can perform a stable oscillation operation.

  FIG. 4 is a circuit diagram of a semiconductor integrated circuit device according to the fourth embodiment of the present invention. 4, the same reference numerals as those in FIG. 3 represent the same items, and the description thereof is omitted. The semiconductor integrated circuit device 10c of FIG. 4 includes a resistance element R7 between the power supply and the non-inverting input terminal (+) of the differential amplifier OPa, and the non-inverting input terminal (+) of the differential amplifier OPa and the ground. A resistance element R8 is provided between them. In this case, the resistance value of the resistance element R1 is equal to the resistance value of the parallel connection of the resistance elements R7 and R8, and the potential at the connection point of the resistance elements R7 and R8 and the DC potential (amplitude center) of the output terminal of the differential amplifier OPa. It is preferable that the potential is equal.

  In the semiconductor integrated circuit device 10c having such a configuration, it is assumed that a leakage current is generated in the electrostatic protection circuit as in the first embodiment. Here, the value of the leakage current flowing from the power supply side to the resistance element R1 via the electrostatic protection circuit 11b is equal to the value of the leakage current flowing from the power supply side to the resistance elements R7 and R8 via the electrostatic protection circuit 11a. Therefore, the resistance value of the resistance element R1 is equal to the resistance value of the parallel connection of the resistance elements R7 and R8, and the potential at the connection point of the resistance elements R7 and R8 is equal to the DC potential of the output terminal of the differential amplifier OPa. As a result, potential fluctuations due to leakage currents at the inverting input terminal (−) and the non-inverting input terminal (+) of the differential amplifier OPa become equal. Therefore, as in the third embodiment, the semiconductor integrated circuit device 10c can perform a stable oscillation operation.

  In the above third and fourth embodiments, the example using the differential amplifier OPa in which the inverting output terminal is omitted is shown. However, the present invention is not limited to this, and the differential amplifier OP having an inverting output terminal may be used to supply the bias to the non-inverting input terminal (+) as in the third and fourth embodiments. Needless to say, it is good.

  In the above description, the electrostatic protection circuit connected to the inverting input terminal and the electrostatic protection circuit connected to the non-inverting input terminal are described as being the same. However, since the non-inverting input terminal is a terminal that is not connected to the external terminal, a circuit having leakage characteristics similar to the electrostatic protection circuit attached to the external terminal can be connected to the non-inverting input terminal. Since the electrostatic protection circuit has a purpose of consuming electrostatic energy, the circuit size is made large. If a circuit having leakage characteristics similar to that of the electrostatic protection circuit is used, the circuit size can be reduced correspondingly, thereby contributing to improvement in the degree of integration.

  It should be noted that the disclosures of the aforementioned patent documents and the like are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea.

1 is a circuit diagram of a semiconductor integrated circuit device according to a first embodiment of the present invention. FIG. 6 is a circuit diagram of a semiconductor integrated circuit device according to a second embodiment of the present invention. FIG. 6 is a circuit diagram of a semiconductor integrated circuit device according to a third example of the present invention. FIG. 6 is a circuit diagram of a semiconductor integrated circuit device according to a fourth example of the present invention.

Explanation of symbols

10, 10a, 10b, 10c Semiconductor integrated circuit devices 11a, 11b, 11c Electrostatic protection circuit C1, C2 Capacitance elements I1, I2 Leakage current OP, OPa Differential amplifier OUT Outputs P1, P2 External terminals R1-R8 Resistance element Vb Bias Supply source XTL Quartz crystal

Claims (7)

A first external terminal capable of connecting one end of an external circuit;
A second external terminal enabling connection of the other end of the external circuit;
A first resistance element;
A second resistance element;
An inverting input terminal is connected to the first external terminal and one end of the first resistance element, an output terminal is connected to the second external terminal and the other end of the first resistance element, and a non-inverting input terminal A differential amplifier that connects to a bias source via the second resistive element;
A first electrostatic protection circuit connected to the inverting input terminal;
A second electrostatic protection circuit connected to the non-inverting input terminal;
Equipped with a,
The differential amplifier further includes an inverting output terminal,
It is configured to output an output signal from the inverting output terminal to an internal circuit,
The semiconductor integrated circuit device according to claim to Rukoto and the inverting output terminal of the bias source. A first external terminal capable of connecting one end of an external circuit;
A second external terminal enabling connection of the other end of the external circuit;
A first resistance element;
A second resistance element;
An inverting input terminal is connected to the first external terminal and one end of the first resistance element, an output terminal is connected to the second external terminal and the other end of the first resistance element, and a non-inverting input terminal A differential amplifier that connects to a bias source via the second resistive element;
A first electrostatic protection circuit connected to the inverting input terminal;
A second electrostatic protection circuit connected to the non-inverting input terminal;
Equipped with a,
The semiconductor integrated circuit device according to claim to Rukoto a predetermined division point of the bias supply said first resistor element. The differential amplifier further includes an inverting output terminal,
3. The semiconductor integrated circuit device according to claim 2 , wherein an output signal is output from the inverting output terminal to an internal circuit.   The first resistance element is divided into third and fourth resistance elements by the predetermined dividing point;
  The inverting input terminal is connected to one end of the third resistance element,
  The output terminal is connected to one end of the fourth resistance element,
  The second resistance element is connected to the other end of the third resistance element and the other end of the fourth resistance element,
  4. The semiconductor integrated circuit device according to claim 2, wherein a resistance value of the second resistance element is equal to a resistance value of the third resistance element.   5. The semiconductor integrated circuit device according to claim 1, further comprising a third electrostatic protection circuit connected to the output terminal.   6. The semiconductor integrated circuit device according to claim 1, wherein the external circuit is a circuit including a solid vibrator and functions as an oscillation circuit.   A first capacitive element connected to the first external terminal;
  A second capacitive element connected to the second external terminal;
  The semiconductor integrated circuit device according to claim 1, further comprising:

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