JP2006032805A - Voltage control oscillation circuit and semiconductor integrated device and wireless communication device using the circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage control oscillation circuit desirable for integration on the same chip because it rarely malfunctions for noise and to provide a semiconductor integrated device and a wireless communication device that employ the above oscillation circuit. <P>SOLUTION: This voltage control oscillation circuit comprises an 8-shaped coil 13 connecting in series the looped coils 11 and 12 so that they can form a point symmetry, a capacitor 16 with variable capacitance diodes 14 and 15 connected to the 8-shaped coil 13 in parallel and a differential amplifier 19 having transistors 17 and 18. The 8-shaped coil 13, capacitor 16 and differential amplifier 19 are positioned symmetrically so that the induced noise arising on the 8-shaped coil 13 will be an in-phase noise for the input terminal of the differential amplifier 19. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a voltage controlled oscillation circuit, and more particularly to a voltage controlled oscillation circuit with less malfunction due to noise, a semiconductor integrated device using the voltage controlled oscillation circuit, and a wireless communication device.

  A wireless communication device such as a mobile communication terminal typified by a mobile phone has a voltage controlled oscillator (VCO) in which an oscillation frequency can be varied by an externally applied voltage in an RF (radio frequency) signal processing unit. is doing.

  The voltage-controlled oscillation circuit is required to minimize the coupling with the surrounding electromagnetic field during high-density mounting in order to reduce the size of the wireless communication device.

  2. Description of the Related Art Conventionally, a voltage controlled oscillation circuit is known in which a coil, a variable capacitance diode whose capacitance can be changed according to an applied voltage, and a transistor are integrated on a substrate (for example, see Patent Document 1).

  In the voltage controlled oscillation circuit used in the wireless communication device disclosed in Patent Document 1, looped series-connected coils that are reversed from each other by printed wiring are formed on a support substrate, and elements other than the coil are formed on the semiconductor substrate. For example, a capacitor, a transistor, or the like is formed. The coil, the capacitor, and the transistor are electrically connected by bringing a bump formed on the back surface of the semiconductor chip into contact with the printed wiring.

  However, the coil disclosed in Patent Document 1 in which the coils of the left and right reversed shapes are connected in series is in-phase connection of the two coils. Therefore, the coil has electromagnetic waves caused by external electromagnetic waves and high-frequency currents flowing through other circuits. Inductive noise coupled with the field is likely to occur. As a result, the voltage controlled oscillation circuit has a problem that spurious is generated by induction noise and the oscillation frequency fluctuates. In particular, fluctuations in the oscillation frequency increase due to noise having a frequency close to the resonance frequency.

  In addition, since the high frequency current generated by the voltage controlled oscillation circuit itself may affect the peripheral circuit, it is difficult to integrate the voltage controlled oscillation circuit and the peripheral circuit such as a high frequency signal processing circuit on one chip. There's a problem.

Therefore, since it is necessary to store the substrate on which the voltage controlled oscillation circuit is mounted in a shielded casing, there is a problem that it is difficult to reduce the size of the apparatus.
JP 2002-252324 A (page 4-6, FIG. 1)

  The present invention provides a voltage controlled oscillation circuit that is less likely to malfunction due to noise, a semiconductor integrated device, and a wireless communication device using the voltage controlled oscillation circuit.

  In order to achieve the above object, a voltage controlled oscillation circuit according to an aspect of the present invention includes an eight-shaped coil connected in series so that loop-shaped coils are point-symmetric with each other, and one anode having the eight-shaped coil. A variable capacitance diode connected to one end of the coil, the other anode connected to the other end of the 8-shaped coil, and the cathode connected in common; the collector of one transistor is the base of the other transistor and the 8 A differential amplifier that is connected to one end of the U-shaped coil, the collector of the other transistor is connected to the base of the one transistor and the other end of the 8-shaped coil, and the emitter is commonly connected. It is characterized by.

  The voltage controlled oscillation circuit according to another aspect of the present invention includes a first eight-shaped coil connected in series so that the loop coils are point-symmetric with each other, and one anode of the first eight-shaped coil. A variable capacity diode connected to one end of the letter-shaped coil, the other anode connected to the other end of the first eight-shaped coil, and the cathode connected in common, and the loop-shaped coil are point-symmetric with each other. And the collector of one transistor is connected to the base of the other transistor and one end of the second 8-shaped coil, and the collector of the other transistor is A differential amplifier connected to the base of the one transistor and the other end of the second 8-shaped coil and having an emitter connected in common, wherein the first and second 8-shaped coils are electromagnetic It is characterized in that it is bound to one another by guide.

  According to the present invention, since the 8-shaped coils connected in series so that the loop-shaped coils are point-symmetric with each other are connected to the differential amplifier, inductive noise due to an external electromagnetic field is generated at the input end of the differential amplifier. Can be in-phase noise.

  As a result, the common-mode noise cancels each other, so that the stability of the oscillation frequency of the voltage controlled oscillation circuit is improved. Therefore, it is possible to provide a highly accurate wireless communication device that is not affected by external noise.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 are diagrams showing a voltage controlled oscillation circuit according to a first embodiment of the present invention, FIG. 1 is a plan view of the voltage controlled oscillation circuit integrated on a semiconductor substrate, and FIG. 2 is a circuit showing an equivalent circuit thereof. 3 is a cross-sectional view thereof, FIG. 3A is a cross-sectional view taken along the line AA in FIG. 1 and viewed in the direction of the arrow, and FIG. 3B is a cross-sectional view taken along the line BB in FIG. It is sectional drawing which cut | disconnected along and was seen in the arrow direction.

  As shown in FIG. 1, the voltage controlled oscillation circuit 10 integrated on the semiconductor substrate of the present embodiment has an 8-shaped coil 13 connected in series so that the loop-shaped coils 11 and 12 are point-symmetric with each other. And a capacitor 16 connected in parallel to the figure-shaped coil 13 and the variable capacitance diodes 14 and 15 connected in series so that the cathodes face each other, and the output of the parallel resonance circuit of the figure-shaped coil 13 and the capacitor 16 Transistors 17 and 18 to be amplified have a differential amplifier 19 connected to the edge.

  In the figure-shaped coil 13, a loop-shaped coil 11 and a loop-shaped coil 12 obtained by rotating the coil 11 180 degrees around one end of the coil 11 are connected in series at the rotation center. Arrows a and b indicate the direction of current flowing in the loop coils 11 and 12 at a certain time.

  The variable capacitance diodes 14 and 15 are arranged in line symmetry so as to be opposed to each other with respect to the line BB, and the transistors 17 and 18 are arranged in line symmetry near the variable capacitance diodes 14 and 15.

As shown in FIG. 2, the capacitor 16 includes variable capacitance diodes 14 and 15, the anode A <b> 1 of the variable capacitance diode 14 is connected to the node A of the coil 11, and the anode A <b> 2 of the variable capacitance diode 15 is the node of the coil 12. Connected to B.
The cathodes K1 and K2 are commonly connected to the control voltage input terminal 21. A control voltage Vcont is applied to the control voltage input terminal 21, and the capacitances of the variable capacitance diodes 14 and 15 are changed by the control voltage.

The differential amplifier 19 includes transistors 17 and 18. The collector C1 of the transistor 17 is connected to the base B2 of the transistor 18 and the node A of the coil 11. The collector C2 of the transistor 18 is connected to the base B1 of the transistor 17 and the coil 12. Connected to node B. The emitters E1 and E2 are commonly grounded.
The collectors C1 and C2 are connected to bias current input terminals 22 and 23, respectively. A bias current is applied to the bias current input terminals 22 and 23, and the differential amplifier 19 is driven by the bias current.

  Thus, a parallel resonance circuit of the figure-shaped coil 13 and the capacitor 16 and an oscillation circuit based on the positive feedback action of the differential amplifier 19 are configured, and oscillates at the parallel resonance frequency.

  As shown in FIG. 3, the voltage controlled oscillation circuit 10 is formed by integrating an 8-shaped coil 13, a capacitor 16, and a differential amplifier 19 on a semiconductor substrate 31.

  A variable capacitance utilizing a junction capacitance generated when a reverse bias is applied to a pn junction in a region where an insulating film 32, for example, a silicon oxide film, is formed on a semiconductor substrate 31 and then a part of the insulating film 32 is removed by etching. The diodes 14 and 15 are formed so that the cathodes K 1 and K 2 face each other and are connected in series by a wiring 33.

  Similarly, the transistors 17 and 18 are formed close to each other between the variable capacitance diodes 14 and 15, and are connected to each other via the wiring 34. The wiring 33 and the wiring 34 are insulated and separated by an insulating film (not shown).

  For example, loop coils 11 and 12 having a line width of about 40 μm, a film thickness of about 3 μm, a diameter of about 220 μm, and an inductance of about 0.3 nH are formed on the insulating film 32 by Al wiring.

  The anode A1 of the variable capacitance diode 14 is connected to the node A of the coil 11 via the via 35, and the anode A2 of the variable capacitance diode 15 is connected to the node B of the coil 12 via the via 36.

  That is, the capacitor 16 and the differential amplifier 19 are formed on the upper surface of the semiconductor substrate 31, and the 8-shaped coil 13 is formed on the insulating film 32 formed on the semiconductor substrate 31.

  In the figure-shaped coil 13 connected in series so that the loop-shaped coils 11 and 12 are point-symmetric with each other, the magnetic fields of the coils 11 and 12 strengthen each other inside the figure-shaped coil 13, and A magnetic field distribution is formed so that the magnetic fields of the coils 11 and 12 cancel each other at a distance from the outside of the character coil 13.

  Thereby, inductive noise generated in the 8-shaped coil 13 by an external electromagnetic field can be in-phase noise with respect to the input terminal of the differential amplifier 19. As a result, the common-mode noise cancels each other, so that the stability of the oscillation frequency of the voltage controlled oscillation circuit 10 can be improved.

  Further, since the magnetic fields far from the outside of the figure-shaped coil 13 cancel each other and are weakened, it is possible to reduce the influence on the peripheral circuit. As a result, it is easy to integrate the voltage controlled oscillation circuit 10 and the peripheral circuit on the same chip, and further, there is an advantage that the casing shield can be simplified.

  FIG. 4 is a block diagram showing a configuration of a wireless communication apparatus using the voltage controlled oscillation circuit 10 shown in FIG.

  As shown in FIG. 4, the wireless communication device 40 of this embodiment includes an antenna 41 that transmits or receives a radio signal, a switch 42 that selects whether the antenna 41 transmits or receives a radio signal, Signal transmitting means 43 for outputting a radio wave signal obtained by processing the input signal inputted from the antenna 41 to the antenna 41, and a signal receiving means 44 for processing the radio wave signal received by the antenna 41 and outputting it to the outside.

  The signal transmission means 43 includes an input signal processing circuit 45 that processes a signal input from the outside, a modulation circuit 47 that modulates the output signal of the first voltage controlled oscillation circuit 46 by the output signal of the input signal processing circuit 45, and a modulation A power amplifier 48 that amplifies the output signal of the circuit 47 and outputs the amplified signal to the antenna 41.

  The signal receiving means 44 includes a low noise amplifier 49 that amplifies the radio signal received by the antenna 41, a mixer 51 that demodulates the radio signal by mixing the output of the low noise amplifier 49 and the output signal of the second voltage controlled oscillation circuit 50, And an output signal processing circuit 52 that processes the demodulated signal and outputs the processed signal to the outside.

  This makes it possible to transmit externally input signals such as audio / image signals compressed by a predetermined compression method and to encode or decode received signals to reproduce the original audio / image signals due to noise malfunction. It is possible to do without.

  As described above, according to this embodiment, since the 8-shaped coil 13 connected in series so that the loop coils 11 and 12 are point-symmetric with each other is connected to the differential amplifier 19, Inductive noise due to the electromagnetic field can be in-phase noise with respect to the input terminal of the differential amplifier 19.

  As a result, the common-mode noise cancels each other, so that the stability of the oscillation frequency of the voltage controlled oscillation circuit 10 is improved. Therefore, it is possible to provide a highly accurate wireless communication device that is not affected by external noise.

  Here, the case where the wireless communication device 40 includes both the signal transmission unit 43 and the signal reception unit 44 has been described, but only one of them may be used.

  5 to 7 are diagrams showing a voltage controlled oscillation circuit according to a second embodiment of the present invention. FIG. 5 is a plan view of the voltage controlled oscillation circuit integrated on a semiconductor substrate. FIG. FIG. 5 (b) is a plan view showing a second 8-shaped coil, FIG. 6 is a circuit diagram showing an equivalent circuit thereof, and FIG. 7 is a sectional view thereof. 7A is a cross-sectional view taken along the line CC in FIG. 5 and viewed in the direction of the arrow, and FIG. 7B is cut along the line DD in FIG. 5 and viewed in the direction of the arrow. It is sectional drawing.

  In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different portions will be described.

  This embodiment is different from the first embodiment in that a parallel resonant circuit having an 8-shaped coil and a capacitor and a differential amplifier for positive feedback amplification of the output of the parallel resonant circuit are electrically separated and magnetically generated by electromagnetic induction. It is to be combined.

  That is, as shown in FIG. 5, the voltage controlled oscillation circuit 60 of this embodiment includes a parallel resonant circuit 61 having a capacitor 16 connected in parallel to an 8-shaped coil 13 and looped coils 62 and 63. It has an 8-shaped coil 64 connected in series so as to be symmetrical, and a differential amplifier 19 connected in parallel to the 8-shaped coil 64, and is electrically separated from the parallel resonant circuit 61, and is electromagnetically induced. And an electromagnetically coupled differential amplifier 65 that is magnetically coupled.

  As shown in FIG. 6, the parallel resonant circuit 61 has an 8-shaped coil 13 and a capacitor 16 connected in parallel, and the magnetically coupled differential amplifier 65 has an 8-shaped coil 64 and a differential amplifier 19 connected in parallel. . The 8-shaped coil 13 and the 8-shaped coil 64 are electrically separated and are magnetically coupled by electromagnetic induction.

  As shown in FIG. 7, the 8-shaped coil 64 on the insulating film 66 has, for example, a line width of about 40 μm, a film thickness of about 3 μm, a diameter of about 220 μm, and an inductance of about 0.3 nH, similar to the loop coils 11 and 12. Loop-shaped coils 62 and 63, and are formed at the same position as the 8-shaped coil 13 on the insulating film 32 so as to be opposed to the 8-shaped coil 13. The insulating film 66 electrically separates the 8-shaped coil 13 and the 8-shaped coil 64 from each other.

  The thickness of the insulating film 66 is not particularly limited as long as it is a distance at which the figure-shaped coil 13 and the figure-shaped coil 64 can be magnetically coupled, but about 3 to 6 μm is appropriate. The TEOS (tetraethoxysilane) film can be easily formed as long as it is a film excellent in step coverage, high flatness, embedding characteristics, etc. Etc. are suitable.

  Since the voltage-controlled oscillation circuit 60 is electrically separated into the parallel resonance circuit 61 and the electromagnetic coupling differential amplifier 65 by the 8-shaped coil 13 and the 8-shaped coil 64, the parallel resonance circuit 61 and the electromagnetic coupling differential amplifier are separated. 65 can be operated under optimum conditions.

  For example, in the parallel resonance circuit 61, the capacitor 16 can be varied without excess or deficiency so as to minimize the deterioration of the Q of the entire resonator, and can be operated so as to cover the variable range with good linearity. In the magnetic coupling differential amplifier 65, the bias current can be set so that the differential amplifier 19 operates at the optimum operating point.

  As described above, the voltage controlled oscillation circuit 60 of this embodiment includes the parallel resonance circuit 61 and the magnetic coupling differential amplifier 65 which are electrically separated and magnetically coupled. There is an advantage that the circuit 61 and the magnetic coupling differential amplifier 65 can be operated under optimum conditions.

  In the above-described embodiment, the case where the 8-shaped coils connected in series so that the loop-shaped coils are point-symmetric with each other has been described, but the present invention is not limited to this, and the two The same effect can be obtained if the coils are arranged so as to be point-symmetric.

  For example, it may be an 8-shaped coil in which a spiral coil and a rectangular coil are connected in series so as to be point-symmetric with each other. Design can be freely made as long as it is within allowable ranges such as required inductance and Q value of the coil and layout on the semiconductor substrate.

1 is a plan view showing a voltage controlled oscillation circuit according to Embodiment 1 of the present invention. 1 is a circuit diagram showing an equivalent circuit of a voltage controlled oscillation circuit according to Embodiment 1 of the present invention. FIG. 3A is a cross-sectional view illustrating the voltage controlled oscillation circuit according to the first embodiment of the present invention. FIG. 3A is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a cross-sectional view taken along the line BB in FIG. 2 and viewed in the direction of the arrow. 1 is a wireless communication apparatus having a voltage controlled oscillation circuit according to a first embodiment of the present invention. 5A is a plan view showing a voltage controlled oscillation circuit according to a second embodiment of the present invention, FIG. 5A is a plan view showing a first 8-shaped coil, and FIG. 5B is a second 8-shaped coil. The top view which shows a coil. The circuit diagram which shows the equivalent circuit of the voltage control oscillation circuit which concerns on Example 2 of this invention. FIG. 7A is a cross-sectional view showing a voltage controlled oscillation circuit according to the second embodiment of the present invention. FIG. 7A is a cross-sectional view taken along the line CC in FIG. FIG. 6 is a cross-sectional view taken along the line DD in FIG. 5 and viewed in the direction of the arrow.

Explanation of symbols

10, 60 Voltage-controlled oscillation circuit 11, 12, 62, 63 Loop-shaped coil 13, 648-shaped coil 14, 15 Variable capacitance diode 16 Capacitor 17, 18 Transistor 19 Differential amplifier 21 Control voltage input terminal 22, 23 Bias Current input terminal 31 Semiconductor substrate 32, 66 Insulating film 33, 34 Wiring 35, 36 Via 40 Wireless communication device 41 Antenna 42 Switch 43 Signal transmission means 44 Signal reception means 45 Input signal processing circuit 46 First voltage control oscillation circuit 47 Modulation Circuit 48 Power amplifier 49 Low noise amplifier 50 Second voltage control oscillation circuit 51 Mixer 52 Output signal processing circuit 61 Parallel resonance circuit 65 Electromagnetic coupling differential amplifier

Claims (5)

8-shaped coils connected in series so that the loop-shaped coils are point-symmetric with each other;
A variable capacitance diode having one anode connected to one end of the 8-shaped coil, the other anode connected to the other end of the 8-shaped coil, and a cathode commonly connected;
The collector of one transistor is connected to the base of the other transistor and one end of the 8-shaped coil, and the collector of the other transistor is connected to the base of the one transistor and the other end of the 8-shaped coil. And a voltage controlled oscillation circuit comprising a differential amplifier having emitters connected in common. A first eight-shaped coil connected in series so that the loop coils are point-symmetric with each other;
A variable capacitance diode having one anode connected to one end of the first 8-shaped coil, the other anode connected to the other end of the first 8-shaped coil, and a cathode commonly connected;
A second eight-shaped coil connected in series so that the loop-shaped coils are point-symmetric with each other;
The collector of one transistor is connected to the base of the other transistor and one end of the second 8-shaped coil, and the collector of the other transistor is connected to the base of the one transistor and the second 8-shaped coil. A differential amplifier connected to the other end of the power source and having a common emitter connected thereto,
The voltage controlled oscillation circuit, wherein the first and second 8-shaped coils are coupled to each other by electromagnetic induction.   2. The semiconductor integrated device having the voltage controlled oscillation circuit according to claim 1, wherein the differential amplifier, the variable capacitance diode, and the 8-shaped coil are integrated on the same chip. A semiconductor integrated device.   3. The semiconductor integrated device having the voltage controlled oscillation circuit according to claim 2, wherein the differential amplifier, the variable capacitance diode, and the first and second 8-shaped coils are integrated on the same chip. A semiconductor integrated device, wherein the first 8-shaped coil and the second 8-shaped coil are formed to face each other at the same position on different planes. Signal transmitting means for modulating the output signal of the first voltage controlled oscillator circuit according to claim 1 or 2 based on an input signal input from outside, and transmitting the modulated output signal from an antenna;
Signal receiving means for demodulating a received signal received by the antenna using an output signal of the second voltage controlled oscillation circuit according to claim 1 or 2, and outputting the demodulated received signal to the outside;
A wireless communication apparatus comprising at least one of the following.

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