JP2007181037A - Ic for oscillator, and voltage-controlled crystal oscillator using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IC for an oscillator which can be simplified including component management by reducing the number of components, and to provide a voltage-controlled oscillator using the same. <P>SOLUTION: The IC 1 for oscillator is configured, so that an IC chip 1a for oscillation having integrated circuit elements forming an oscillation circuit together with a crystal resonator 2 is firmly fixed on a conductive plate 5, and a lead terminal 7 electrically connected to the IC chip 1a for oscillation is exposed to the external surface and is molded with a resin 9. This IC 1 has a configuration in which a semiconductor chip of a variable capacitance diode having the oscillation circuit of a voltage-controlled type is firmly fixed on the conductive plate 5, and is molded with the resin 9 together with the IC chip. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an IC chip for an oscillator and a voltage controlled crystal oscillator (hereinafter referred to as a voltage controlled oscillator) using the IC chip, and more particularly to a voltage controlled oscillator simplified by reducing the number of components.

(Background of the Invention)
Since the crystal oscillator has high frequency stability, the voltage controlled oscillator according to this is adopted as a reference signal source of a PLL control circuit, for example. In recent years, many of the circuit elements constituting the voltage controlled oscillator have been integrated, the number of parts is reduced, and the miniaturization is promoted, contributing to the downsizing of electronic devices.

(Example of conventional technology)
4 and 5 are diagrams for explaining a conventional example, FIG. 4 is a circuit diagram of a voltage controlled oscillator, FIG. 5 (a) is a plan view in the manufacturing process of the oscillator IC, and FIG. ) Is a sectional view of the same.

  The voltage controlled oscillator generally includes an oscillator IC 1, a crystal resonator 2, a varicap diode 3, and an extension coil 4. In the oscillator IC 1, for example, an oscillation IC chip 1 a which is a bare chip is fixed on the conductive plate 5, and each IC terminal (not shown) on the circuit function surface (one main surface) and the lead terminal 7 connected to the frame 6 are bonded by wire bonding. They are connected by a gold wire 8 and integrated by a resin mold 9. Then, the frame 6 is divided individually.

  The oscillation IC chip 1a is formed by integrating a crystal oscillator 2 and at least a dividing capacitor 10 (ab) forming an oscillation circuit and an oscillation amplifier 11 including an inverter. Each IC terminal on the circuit function surface (one main surface) includes a power supply terminal (Vcc), an output terminal (Vout), a cathode connection terminal (VDc) of the varicap diode 3, a ground terminal (E), and a crystal terminal (X1). ) And a dummy terminal (NC). Note that the conductive plate 5 extends from the lead terminal 7 (E) and the dummy terminal (NC) for grounding, and the lead terminals 7 other than them are independent of the conductive plate 5. These lead terminals 7 are arranged on both sides of the IC chip.

  The crystal resonator 2 has reactance characteristics (resonance characteristics) as shown in FIG. 6 (solid line), and an inductive region between the series resonance point fs and the parallel resonance point fp is used. Thereby, it functions as an inductor component. Then, the dividing capacitor 10 (ab) and the resonance circuit 12 in the oscillation IC chip 1a are formed. The oscillation amplifier 11 in the oscillation IC chip is composed of, for example, a C-MOS type inverter, and is connected to the resonance circuit 12 for feedback amplification. In short, the resonance circuit 12 and the oscillation amplifier 11 form an oscillation closed loop.

  The oscillation frequency generally depends on the resonance frequency of the resonance circuit 12 and is accurately determined by a series equivalent capacitance on the circuit side viewed from both ends of the crystal resonator 2 so-called load capacitance. That is, the resonance frequency between the inductor component of the crystal unit 2 and the series equivalent capacitance is the oscillation frequency.

  The varicap diode 3 is connected in parallel with one of the dividing capacitors 10a, and a control voltage Vc is applied to the connection point. Reference numeral 13 is a DC blocking capacitor, and 14 is a harmonic blocking resistor. The extension coil 4 is connected in series to the crystal unit 2 in the resonance circuit 12. In short, both of them are inserted into the resonance circuit 12 in the oscillation closed loop.

  The varicap diode 3 is formed by integrating a semiconductor chip (hereinafter referred to as a VD chip) 3a which is a bare chip in the same manner as the IC chip by a resin mold 9 (FIG. 7). In this case, the anode serving as the lower surface of the VD chip 3a is fixed to one lead terminal 7 '(VDa), and the cathode serving as the upper surface is attached to the other lead terminal 7' (VDc) by wire bonding. 8 and resin molding. The cathode of the VD chip 3a is connected to the VD terminal 7 (VDc) of the oscillator IC 1 and the anode is connected to the ground terminal 7 (E).

  Then, the control voltage Vc is applied as a reverse voltage to the cathode of the varicap diode 3 through the harmonic blocking resistor 14. As a result, the load capacitance changes to vary the oscillation frequency. The varicap diode 3 can be replaced (also used) with one of the divided capacitors 10a, for example. Further, both can be varicap diodes 3. The harmonic element resistor 14 is also externally attached because the varicap diode 3 is externally attached as a discrete.

Further, since the extension coil 4 is connected in series to the crystal resonator 2, the inductor component is increased as shown by the curve (dotted line) in FIG. 6, so that the series resonance point fs is moved to the low frequency side and fs ′. And Thereby, the inductive region of the crystal unit 2 is expanded, and the variable range of the oscillation frequency can be expanded. In addition, since it is necessary to change the reactance value according to the characteristic of each crystal oscillator 2, the extension coil 4 is a discrete type.
JP 2001-44757 A JP 2001-217651 A

(Problems of conventional technology)
However, in the voltage controlled oscillator having the above configuration, the oscillation IC chip 1a and the VD chip 3a are the same semiconductor chip, but the VD chip 3a has a super-step structure and is different from the oscillation IC chip 1a in which the oscillation circuit is integrated. The manufacturing process is different. Therefore, the varicap diode 3 cannot be integrated on the IC chip, and becomes a VD chip 3a independent of this.

  This increases the number of components of the voltage controlled oscillator, complicates component management, increases the number of steps for mounting on the oscillation substrate, and decreases productivity. In addition, there is a problem in that downsizing is hindered by increasing the mounting area for the oscillation substrate.

(Object of invention)
The present invention provides an oscillator IC 1 that can be simplified including parts management by reducing the number of parts, and a voltage controlled oscillator using the same.

  In the present invention, as shown in the claims (Claim 1), an oscillation IC chip in which circuit elements forming an oscillation circuit together with a crystal resonator are integrated is fixed on a conductive plate, and the oscillation IC In the oscillator IC that is resin-molded by exposing the lead terminal electrically connected to the chip to the outer surface, a semiconductor chip of a varicap diode having a voltage-controlled oscillation circuit is fixed on the conductive plate, The resin mold is used together with the IC chip.

  According to the second aspect of the present invention, an oscillation IC chip in which circuit elements that form an oscillation circuit together with a crystal resonator are integrated is fixed on a conductive plate, and a lead terminal electrically connected to the oscillation IC chip is removed. An oscillation IC exposed on the surface and resin-molded, a varicap diode having the oscillation circuit as a voltage control type, and an extension coil that lowers the series resonance frequency of the crystal resonator and widens the frequency variable range. In the voltage controlled crystal oscillator, the semiconductor chip of the varicap diode is fixed on the conductive plate and resin-molded together with the IC chip.

  According to the first and second aspects of the present invention, since the VD chip is fixed to the conductive plate to which the oscillation IC chip is fixed and resin-molded, the oscillation IC and the voltage control type in which the oscillation circuit is integrated are provided. The so-called VD chip is modularized. As a result, the number of parts constituting the voltage controlled oscillator can be reduced, and parts management, productivity, and downsizing can be promoted to simplify the whole.

  FIG. 1 is a plan view of a voltage-controlled oscillator IC for explaining an embodiment of the present invention during the manufacturing process. In addition, description of the same part as a prior art example is simplified or abbreviate | omitted.

  The voltage-controlled oscillator IC 1 is formed by integrally molding an oscillation IC chip 1a integrated with at least an oscillation circuit and a VD chip 3a (a semiconductor chip for the varicap diode 3). That is, the oscillation IC chip 1a and the VD chip 3a are fixed to the conductive plate 5 of the oscillator IC 1 described above. Here, the projecting portion 5a is provided on the conductive plate 5 having the ground potential, and the anode serving as the lower surface of the VD chip 3a is fixed on the projecting portion. The protruding portion 5a protrudes between the cathode connection terminal 7 (VDc) and the lead terminal 7 (Vout) adjacent thereto.

  The cathode on the upper surface of the VD chip 3a is connected to the lead terminal 7 (VDc) to which the VD terminal of the oscillator IC 1 is connected by a gold wire 8 for wire bonding. Then, one end portion of the oscillation IC chip 1a, the conductive plate 5, the wire bonding gold wire 8 and each lead terminal 7 connected thereto is integrated by a resin mold 9, and the other end portion of the lead terminal 7 is exposed to the outer surface. To do. In addition, after resin molding, it cut | disconnects from the flame | frame 6 and is divided | segmented into each IC chip 1 for oscillators.

  FIG. 2 is a circuit diagram of a voltage controlled oscillator using such an oscillator IC 1, and shows a modularized oscillator IC 1 in which a dotted line frame portion is a voltage controlled type. According to this, the varicap diode 3 is integrated into the oscillator IC 1. Therefore, the mounting area can be reduced as shown in the layout diagram of FIG. 3 (plan view) with respect to the set substrate as compared with the conventional example. However, the third (a) is an example of the arrangement according to the present invention, the same figure (b) is an arrangement example according to the conventional example, and the reference numeral 16 is a circuit pattern.

  In this case, the resin mold and the pair of lead terminals 7 'covering the conventional VD chip 3a are not necessary, and the resin mold 9 and the lead terminal 7 (VDc) of the oscillation IC 1 are also used. Therefore, it is possible to obtain the oscillation IC 1 as a voltage control type module having a small mounting area. Further, since the frame 6 for manufacturing the varicap diode 3 is also used as the frame 6 of the oscillation IC 1, the manufacturing process can be simplified.

(Other matters)
In the above embodiment, the high-frequency blocking resistor is arranged outside the oscillation IC, but can be integrated into the oscillator IC 1. The oscillation amplifier of the oscillation circuit uses an inverter amplifying element, but can be similarly applied to a transistor, for example.

It is a top view in the manufacturing process of IC for oscillators explaining one Embodiment of this invention. 1 is a circuit diagram of a voltage controlled oscillator using an oscillation IC chip according to an embodiment of the present invention. FIG. It is a comparison figure with the prior art example explaining the effect of one Embodiment of this invention, The figure (a) is this invention, The figure (b) is a layout of a prior art example. It is a circuit diagram of a voltage controlled oscillator for explaining a conventional example. It is a figure explaining a prior art example, the figure (a) is a top view in the manufacturing process of IC for oscillators, and the figure (a) is sectional drawing. FIG. 6 is a reactance characteristic diagram of a crystal resonator for explaining a conventional example. It is a top view in the manufacturing process of the varicap diode explaining a prior art example.

Explanation of symbols

  1 Oscillator IC, 2 Crystal resonator, 3 Varicap diode, 4 Extension coil, 5 Conductive plate, 6 Frame, 7, 7 'Lead terminal, 8 Gold wire, 9 Resin mold, 10 Split capacitor, 11 Oscillation amplifier, 12 resonant circuit, 13 DC blocking capacitor, 14 harmonic blocking resistor.

Claims (2)

  An oscillation IC chip that integrates a circuit element that forms an oscillation circuit together with a crystal resonator is fixed on a conductive plate, and a lead terminal electrically connected to the oscillation IC chip is exposed on the outer surface and resin molded. In this oscillator IC, a semiconductor chip of a varicap diode whose voltage is controlled by the oscillation circuit is fixed on the conductive plate and is resin-molded together with the IC chip.   An oscillation IC chip, in which circuit elements that form an oscillation circuit together with a crystal resonator are integrated, is fixed on a conductive plate, and lead terminals electrically connected to the oscillation IC chip are exposed on the outer surface and resin molded. In the voltage controlled crystal oscillator, comprising: the oscillation IC; the varicap diode that makes the oscillation circuit a voltage control type; and the expansion coil that lowers the series resonance frequency of the crystal resonator to widen the frequency variable range. A voltage-controlled crystal oscillator, wherein a semiconductor chip of a cap diode is fixed on the conductive plate and resin-molded together with the IC chip.

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