a2) United States Patent (10) Patent No:—US 6,603,343 B2
`
`Yamaguchiet al.
`(45) Date of Patent:
`Aug. 5, 2003
`
`
`US006603343B2
`
`(54) PHASE CORRECTION CIRCUIT FOR
`TRANSISTOR USING HIGH-FREQUENCY
`SIGNAL
`
`5,617,048 A *
`6,278,313 Bl *
`
`4/1997 Ward et ale .cseccscsssssen 327/143
`8/2001 Kakuta et al. ccc 327/317
`
`FOREIGN PATENT DOCUMENTS
`
`(75)
`
`Inventors: Mamiko Yamaguchi, Tokyo (JP);
`Yoshinobu Sasaki, Tokyo (JP)
`(73) Assignee: Mitsubishi Denki Kabushiki Kaisha,
`Tokyo (JP)
`
`JP
`JP
`IP
`
`3-258008
`11-74367
`1137713
`-
`
`11/1991
`3/1999
`2
`/1999
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`(21) Appl. No.: 10/171,983
`(22)
`Filed:
`Jun. 17, 2002
`(65)
`Prior Publication Data
`US 2003/0112054 A1 Jun. 19, 2003
`
`(30)
`Foreign Application Priority Data
`Dec. 18, 2001
`(IP) wos ieeeeeceesseesecneeeenaes 2001-384257
`(S51)
`Int. C1?eee H03L 35/00; HO3K 17/78
`(52) US. C1. cece cescnseeeecnesenseecenseesenecassenees 327/513
`(58) Field of Search oo... eee 327/512, 513,
`327/580, 584, 314, 317, 320, 325, 326
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`* cited by examiner
`
`Primary Examiner—My-Trang Nu Ton
`(74) Attorney, Agent, or Firm—Leydig, Voit & Mayer, Ltd.
`(57)
`ABSTRACT
`In order to stabilize a phase of an output signal of a
`transistor, a phase correction circuit includes: a) a circuit
`element connected in parallel to a gate of the transistor, an
`:
`:
`'
`a
`impedance including a reactance changing in response to a
`potential difference; and b) a voltage control circuit
`to
`decrease the reactance component
`in response to the
`increase in potential of the gate, wherein total reactance
`component of the circuit element and the transistor is
`maintained to a predetermined value. Because of the func-
`tion of the phase correction circuit, another circuit using the
`.
`.
`output signal of the transistor can work correctly.
`
`3,584,233 A *
`
`6/1971 Cath et al. vices 327/362
`
`4 Claims, 6 Drawing Sheets
`
`CIRCUIT Me a ee ee eee ee ee ee eee ee wee ae
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`HIGH-FREQUENCY
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`1
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`EXHIBIT 1001
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`EXHIBIT 1001
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`1
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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 1 of6
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`US 6,603,343 B2
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`2
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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 2 of6
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`US 6,603,343 B2
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`Fig.4
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`Vab
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`2.0
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`1.5
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`3
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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 3 of6
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`US 6,603,343 B2
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`Fig.7
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`1.5
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`2.0
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`Vab
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`Cd
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`Cd2
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`Cd1
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`Fig.9
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`Cd+Ccas
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`4
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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 4 of6
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`US 6,603,343 B2
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`Fig. 10
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`Vg2=—5V t
`Vgl=—-1V
`ae me ee ee ew wm ee ee ee ee em ee eee
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`5
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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 5 of6
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`US 6,603,343 B2
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`Fig.12A
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`Fig.12B
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`VIA-HOLE 110
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`G
`
`FET 100
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`[>] }
`|
`~100 ===}DIODE 21
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`
` VIA-HOLE 111
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`Fig.13A
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`Fig.13B
`
`[pd
`
`FET 100
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`VIAHOLE 112
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`41~
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`424
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`—~100 a }oie 41,42
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`6
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`

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`U.S. Patent
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`Aug. 5, 2003
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`Sheet 6 of6
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`US 6,603,343 B2
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`Fig.14 PRIOR ART
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`7
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`US 6,603,343 B2
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`1
`PHASE CORRECTION CIRCUIT FOR
`TRANSISTOR USING HIGH-FREQUENCY
`SIGNAL
`
`FIELD OF THE INVENTION
`
`The present invention relates to a phase correction circuit
`for a transistor using a high-frequency signal, which is used
`for a radio communication device, for example.
`
`BACKGROUND OF THE INVENTION
`
`It has been well knownto those skilled in the art that a
`threshold voltage V,,, of a gate of a transistor is increased
`by an increase in the temperature of the transistor. If the
`threshold voltage V,,; has been increased, a high-level
`voltage of a control signal supplied to the gate needs to
`increase up to a value correspondingto the increased thresh-
`old voltage V;,,, so that the transistor can work correctly.
`Otherwise, other circuits provided on the downstream side
`of the transistor and using an output signal of the transistor
`cannot work correctly.
`In order to solve the problem, a temperature compensa-
`tion circuit has been proposed so far. The circuit supplies a
`compensation voltage which increases together with the
`increase in temperature of the transistor, so that the transistor
`can work correctly, even if the high-level voltage of the
`control signalis fixed irrelevant to its temperature change.
`FIG. 14 shows a depletion type n-channel field effect
`transistor 100 of which a gate is connected to not only a
`control signal
`line but also a temperature compensation
`circuit 10. A threshold voltage V;,, of the transistor 100 is
`-1.5V. Adrainofthe transistor 100 is supplied with a voltage
`Vcc. A source of the transistor 100 is connected to the
`ground. Also, the drain of the transistor 100 is connected to
`a high-frequency circuit 200.
`The temperature compensation circuit 10 functions as a
`potential dividing circuit. The circuit 10 has a load circuit 11
`and a resistor 12 connected in series to the load circuit 11.
`The joint P1 between the load circuit 11 and the resistor 12
`is connected to the gate of the transistor 100. More
`particularly, the load circuit 11 has three diodes 11a, 11b and
`11c, connected in series and supplied with a forward bias. A
`terminal 13 beside the load circuit 11 is supplied with
`Vgl=—lv. A terminal 14 beside the resistor 12 is supplied
`with Vg2=—5v. A resistance Rd of the load circuit 11 is
`increased by a temperature increase. This is caused by a
`well-known temperature characteristic of the diode being
`supplied with forward bias, ie., each resistance of the
`forward biased diode 11a, 11b and 11c is increased by the
`temperature increase.
`A potential of the joint P1, or a compensation voltage
`being supplied to the gate of the transistor 100 is increased
`by an increase in resistance Rdofthe load circuit 11 with the
`temperature increase. An incremental ratio of the compen-
`sation voltage for the temperature increase is determined
`identically to that of the threshold V,,, of the transistor 100
`for the temperature increase. Therefore, the transistor 100
`can work correctly, even if the high-level voltage control
`signal is not changed with the increase in temperature of the
`transistor 100.
`
`As described above, the temperature compensation circuit
`10 can supply the compensation voltage increasing together
`with the increase in temperature of the transistor 100 to the
`gate of the transistor 100. If the transistor 100 having the
`temperature compensation circuit 10 is used as a transistor
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`for a high-frequencycircuit, it causes a problem that a phase
`of output signal from the transistor 100 is shifted together
`with the increase in supply voltage, because a depletion
`capacitance increases together with the increase in supply
`voltage. If an amountof phase shift is increased, a following
`high-frequency circuit 200 can not work correctly.
`As the phase correction circuit for a transistor using a
`high-frequency signal, several circuits have been proposed
`in various documents: a phase temperature compensation
`high frequency amplifier in JP A 03-258008, a semiconduc-
`tor device and amplifier in JP A 11-74367, and a peaking
`circuit in JP A 01-137713, for example.
`The phase temperature compensation high frequency
`amplifier in JP A 03-258008 has a circuit functioning as a
`phase correction circuit. The circuit has a varactor diode and
`a potential dividing circuit, adjusting a supply voltage of the
`varactor diode. The potential dividing circuit uses a positive
`thermistor having a resistance varying with its temperature.
`It is well known by those skilled in the art that the relation-
`ship of the capacitance of the varactor diode to the supply
`voltage is determined by a state of a p-n junction. Thatis, at
`the step junction, the depletion capacitance of the varactor
`diode changes in simple proportion to the square root of the
`supply voltage.
`In addition, at
`the graded junction,
`the
`depletion capacitance of the varactor diode changes in
`inverse proportion to the cube root of the supply voltage. On
`the contrary,
`the depletion capacitance of the transistor
`changes in simple proportion to the increase of its tempera-
`ture. Therefore a compensated phase does not indicate any
`constant value in relation to its temperature change, or
`cannot have a linear relationship as described in JP A
`03-258008.
`In addition,
`the semiconductor chip size
`becomes large because the amplifier needs to include not
`only the varactor diode but also a potential dividing circuit.
`The semiconductor device and amplifier in JP A 11-74367
`uses a diode that is inverse connected to another diode in an
`equivalent circuit of a transistor. The circuit supplies an
`inverse bias to the inverse connected diode. An electric
`
`potential of the inverse bias is set the same potential of the
`diode in the equivalent circuit. Therefore the capacitance
`changes of each of the diodes are canceled and therefore
`secondary unsymmetrical wave distortion can be removed.
`Nevertheless, this circuit cannot correct a phase shift caused
`by the increase in threshold voltage.
`In addition, JP A
`11-74367 fails to disclose any circuit to correct a phase shift
`being caused by the temperature increase.
`The peaking circuit in JP A 01-137713 can adjust a phase
`of an output signal from a transistor by meansofa side-gate
`at a constant environment temperature. However,the circuit
`is not constructed to correct a phase shift caused by the
`increase in threshold voltage V,,,; due to the temperature
`increase. Also, in this third document,there is no description
`of a circuit to correct a phase shift caused by the temperature
`increase. In addition, the compensation circuit described in
`the third document is an only circuit to cancellation an
`influence from the side-gate.
`SUMMARYOF THE INVENTION
`
`Therefore, a purpose of the present inventionis to provide
`a phase correction circuit to stabilize a phase of an output
`signalof the transistor, even if its gate potential is increased
`by a temperature compensation function, the temperature
`increase and the other reasons.
`
`To this end, the phase correction circuit for the transistor
`using high-frequency signal, comprising: a) a circuit ele-
`ment connected in parallel to a gate of the transistor together
`
`8
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`US 6,603,343 B2
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`3
`with a control signal line, an impedance including a reac-
`tance componentof the circuit element being changed by a
`potential difference between an input terminal and an output
`terminal of the circuit element; and b) a voltage control
`circuit for adjusting a supply voltage to the circuit element
`to decrease the reactance component
`in response to an
`increase in potential of the gate, wherein a total value of
`reactance components of the circuit element and the tran-
`sistor is set to a predetermined value, so that another circuit
`using an output of the transistor can work correctly.
`In another aspect of the present invention,
`the circuit
`element may be a diode of which a cathode is connected to
`the gate of the transistor. In this case, the voltage control
`circuit supplies predetermined reverse bias to the diode.
`In another aspect of the present invention,
`the circuit
`element may be a diode of which a cathode is connected
`directly or indirectly to the gate of the transistor and a
`transmission line connected in series to the anode or cathode
`of the diode. In this case, the voltage control circuit supplies
`predetermined reverse bias to the diode.
`the circuit
`In another aspect of the present invention,
`element may be two diodes of that the cathodes connected
`each other. One anode of the two diodes is connected to the
`gate ofthe transistor. In this case, the voltage control circuit
`supplies predetermined reverse bias to another anode of the
`two diodes.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`of the
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`of the
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`of the
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`of the
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`of the
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`FIG. 1 is a circuit diagram showing a phase correction
`circuit of a first embodiment;
`FIG. 2 is a temperature characteristic diagram
`threshold V7;;
`FIG. 3 is a temperature characteristic diagram
`resistance Rd;
`FIG. 4 is a temperature characteristic diagram
`potential voltage of the point P1;
`FIG. 5 is a temperature characteristic diagram
`depletion capacitance C,,, of the transistor;
`FIG. 6 is a temperature characteristic diagram
`potential voltage of V,,;
`FIG. 7 is a characteristic of the depletion capacitance Cd
`of the diode in relation to the potential voltage V,,,;
`FIG. 8 is a temperature characteristic diagram of the
`depletion capacitance Cd of the diode;
`FIG. 9 is a temperature characteristic diagram of the
`capacitance C,.+Cd;
`FIG. 10 is a circuit diagram showing a phase correction
`circuit of a second embodiment;
`FIG. 11 is a circuit diagram showing a phase correction
`circuit of a third embodiment;
`FIG. 12A is a partial circuit diagram showing the phase
`correction circuit of the first embodiment;
`FIG. 12Bis a diagram showinga partial layout pattern of
`the phase correction circuit of the first embodiment;
`FIG. 13A is a partial circuit diagram showing the phase
`correction circuit of the third embodiment;
`FIG. 13B is a diagram showinga partial layout pattern of
`the phase correction circuit of the third embodiment; and
`FIG. 14 is a circuit diagram showing a transistor with a
`well-known temperature compensation circuit.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`With reference to the drawings, several embodiments of
`the present invention will be described in detail hereinafter.
`It should be noted that like reference numerals designate like
`parts throughout the drawings.
`
`4
`FIRST EMBODIMENT
`
`FIG. 1 showsa transistor 100 for high-frequency signal of
`whicha gate is connected to not only a control signal line but
`also a well-known temperature compensation circuit 10 and
`a phase correction circuit 20. The transistor 100 is a deple-
`tion type n-channelfield effect transistor and its threshold
`Vez 18 -1.5V at a temperature T1. A drain of the transistor
`100 is supplied with a supply voltage Vcc. A source of the
`transistor 100 is connected to a ground. Also, a drain of the
`transistor 100 is connected to a high-frequencycircuit 200.
`As shownin FIG. 2, the threshold V,,, of the transistor 100
`increases from -1.5V to -1.0V when the transistor’s tem-
`
`perature increases T1 to T2.
`Before a detail explanation about the phase correction
`circuit 20 is described, a simple explanation about
`the
`temperature compensation circuit 10 will be made.
`The temperature compensation circuit 10 functions as a
`potential dividing circuit. The circuit 10 has a load circuit 11
`and a resistor 12 connected in series to the load circuit 11.
`A joint P1 between the load circuit 11 and the resistor 12 is
`connectedto the gate of the transistor 100. More particularly,
`the load circuit 11 has three diodes Ila, 11b and 11c
`connected in series and supplied with forward bias. A
`terminal 13 beside the load circuit 11 is supplied with
`Vel=-1V. A terminal 14 beside the resistor 12 is supplied
`with Vg2=-5V.
`As shownin FIG. 3, a resistance Rd of the load circuit 11
`increases Rd1 to Rd2 together with an increase in tempera-
`ture T1 to T2. Also, as shownin FIG. 4, a potential voltage
`of the point P1, or a compensation voltage being supplied to
`the gate of the transistor 100, increases by 0.5V in response
`to an increase in resistance Rd. The change ratio of the
`compensation voltage in the temperature increaseis set to be
`substantially identical to that of the threshold V,,, in the
`temperature increase. Therefore, the transistor 100 always
`can work correctly, even if the high-level voltage of the
`control signal does not changes by the temperature increase.
`However,
`the temperature increase causes not only an
`increase in threshold V,,, but also an increase in depletion
`capacitance. For example, when the compensation voltage
`(the potential voltage of the point P1) is increased by 0.5V,
`a depletion capacitance Cg,, between the gate and the
`source of the transistor 100 is increased from Cg., to Ces>
`as shownin FIG. 5.
`
`The phase correction circuit 20 includes the reactance
`component Cd of its impedance to decrease inversely with
`the increase in depletion capacitance C,, caused by the
`temperature increase. Therefore, the total capacitance of Cg.
`and Cd approaches to a substantially constant value, as
`shown in FIG. 9.
`
`The phase correction circuit 20 is connected to the gate of
`the transistor 100 together with the control signal line. The
`phase correction circuit 20 has a diode 21 as a circuit
`element of which a reactance componentofits impedanceis
`varied by a potential difference of between an input terminal
`and an output terminal of the diode 21.
`Acathodeof the diode 21 is connected with the gate ofthe
`transistor 100. An anode of the diode 21 is connected with
`
`the voltage-supplying terminal 22. The voltage terminal 22
`is supplied with Vg3=-3V. Therefore, a potential of the gate
`is always higher than a potential of the terminal 22.
`The phase correction circuit 20 having diode 21 and the
`terminal 22, functioning as a voltage control circuit, adjusts
`potential difference between the input
`terminal and the
`output
`terminal of the diode 21 in order to decrease a
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`US 6,603,343 B2
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`reactance componentof the diode 21 in accordance with an
`increase in potential of the gate of the transistor 100.
`The depletion capacitance Cd of the diode 21 decreases
`inversely with the increase in potential of the gate of the
`transistor 100 in orderthat the total capacitance of Cg, and
`Cd reaches a substantially constant value, so that the fol-
`lowing high-frequency circuit 200 using an output signal of
`the transistor 100 can function correctly.
`FIG. 6 shows a temperature characteristic diagram of a
`potential difference Vab between a terminal-a and a
`terminal-b of the diode 21. The potential difference Vab
`increases from 1.5V to 2.0V in response to the increase in
`temperature from T1 to T2 (T2>T1). This change is caused
`by an increase in voltage supplied to the gate of the transistor
`100. This voltage increment is caused by a function of a
`temperature compensation circuit 10 with the temperature
`increase.
`
`FIG. 7 showsa character of the depletion capacitance Cd
`to the potential difference Vab. The depletion capacitance Cd
`decreases from Cd2 to Cdl (Cd1<Cd2) in response to the
`increase in potential difference Vab. This change is caused
`by a well-known character of an inverse connected and
`inverse biased pin diode.
`FIG. 8 shows a temperature characteristic diagram of the
`depletion capacitance Cd. The depletion capacitance Cd
`decreases from Cd2 to Cdl in response to the increase in
`temperature from T1 to T2 (T2>T1). This change is caused
`by the increase in temperature from T1 to T2 (T2>T1) due
`to the function of the temperature compensation circuit 10
`with the temperature increase.
`FIG. 9 shows a temperature characteristic diagram of the
`total capacitance of Cd and C,,. The total capacitance of Cd
`and C,, is maintained constantirrelevant to the temperature.
`This can be attained by the set of an appropriate diode 21 of
`which a temperature characteristic of depletion capacitance
`Cd has an inverse temperature characteristic of depletion
`capacitance C,, of the transistor 100.
`The phrase of “Thetotal capacitance of Cd and C,,, shows
`a constant value” meansthat a phase shift caused by the total
`capacitance of Cd and C,,, provides no adverse affect to the
`high-frequencycircuit 200. Also, this definition of “the total
`capacitance of Cd and C,,, shows a constant value” can be
`used in each phasecorrection circuits 20,30 in the following
`embodiments.
`
`In an embodiment of semiconductor circuit having the
`transistor 100 of which the gate is connected with the
`temperature compensation circuit 10 and the phase correc-
`tion circuit 20, a size of the semiconductor circuit can be
`reduced, in compared with another semiconductor circuit
`using the transistor 100 connected with the circuit 10 and an
`adjusting means for adjusting the phase of the output signal
`of the transistor 100, because the phase correction circuit 20
`has a simple construction. Specifically,the circuit 20 has one
`diode 21 and twolines supplying an inverse bias that varies
`with a voltage of the gate of the transistor 100 to the diode
`21. However, in the case where the transistor 100 connected
`with the circuit 10 and the adjusting meansare used for the
`semiconductor circuit, the adjusting means need two com-
`plex circuits. One circuit is a detecting circuit for detecting
`a reference signal and an amount of a phase shift, and
`anothercircuit is an adjusting circuit for adjusting a shifted
`signal according to the reference signal. Each phase correc-
`tion circuit 30,40 in the following embodiments described
`below can also reduce the semiconductor circuit size by
`similar reasons.
`
`SECOND EMBODIMENT
`
`FIG. 10 shows a transistor 100 of which the gate is
`connected with the temperature compensation circuit 10 and
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`a phase correction circuit 30. The drain of the transistor 100
`is supplied with Vcc. The source of the transistor 100 is
`connected to a ground. Also, the drain of the transistor 100
`is connected to the high-frequency circuit 200.
`The phase correction circuit 30 uses a loaded line type
`phase device as a circuit element which is connected in
`parallel to the gate of the transistor 100 together with a
`control signal line, and of which an impedance including
`reactance componentis changed by the potential difference
`between its input and output terminals. The loaded line type
`device has a diode 31 and a transmission line 32. A cathode
`of the diode 31 is turnedto the gate of the transistor 100. The
`transmission line 32 is connected serially to the diode 31.
`Also, in the phase correction circuit 30, a terminal 34 of
`the transmission line 32 is connected to the gate of the
`transistor 100. A terminal 31 of an anode of the diode 31 is
`supplied with Vg3=-3V. Therefore, the circuit 30 can func-
`tion as a voltage control circuit that can adjust the supply
`voltage to the diode 31 in order to decrease the reactance
`component according to the increase in potential of the gate
`of the transistor 100.
`
`The phase correction circuit 30 of second embodiment has
`not only a phase correctable function effected by a diode 21
`of the phase correction circuit 20 of first embodiment but
`also an additional phase correctable function effected by a
`reactance componentof the transmission line 32. Therefore,
`the phase correction circuit 30 can adjust flexibly a phase of
`an output signal of the transistor 100 to a request of the
`high-frequency circuit 200.
`It should be noted that, a connecting order of the diode 31
`and the transmission line 32 is replaceable.
`THIRD EMBODIMENT
`
`FIG. 11 showsthe transistor 100 of which the gate is
`connected not only to the control signal line but also to the
`temperature compensation circuit 10 and a phase correction
`circuit 40 of third embodiment. The drain of the transistor
`
`100 is supplied with power supply Vcc. The source of the
`transistor 100 is connected to a ground. Also,the drain of the
`transistor 100 is connected to the high-frequency circuit 200.
`The phase correction circuit 40 uses two diodes 41,42 of
`which cathodes are connected to each other to form a circuit
`
`element which is connected in parallel to the gate of the
`transistor 100 together with a control signal line, and of
`which the impedance including reactance component
`is
`changed by the potential difference between its input and
`output terminals. Because both cathodes of the diodes 41,42
`are formed into a single unit in a semiconductorcircuit, a
`size of layout pattern can be reduced.
`Also, in the phase correction circuit 40, an anode of the
`diode 42 is connected to the gate of the transistor 100. A
`terminal 43 of the anode of the diode 41 is supplied with
`Vg3=-3V in order to set a potential of the gate of the
`transistor 100 higher than a potential of the terminal 43.
`Therefore,
`the circuit 40 can work as a voltage control
`circuit which adjusts the supply voltage to the diode 41 in
`order to decrease the reactance component in accordance
`with the increase in potential of the gate of the transistor 100.
`FIG. 12A showsa connecting phase of the diode 21 of the
`phase correction circuit 20 of first embodiment and the
`transistor 100. FIG. 12B shows a layout pattern of the
`connecting phase. As shown in FIG. 12B,
`in the phase
`correction circuit 20, two via-holes 110,111 are needed in the
`layout pattern.
`FIG. 13A shows a connecting phase of the diodes 41,42
`of the phase correction circuit 40 of the third embodiment
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`US 6,603,343 B2
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`7
`and the transistor 100. FIG. 13B shows a layout pattern of
`the connecting phase. As shown in FIG. 13B, since the
`cathodes of the diodes 41,42 are made with a single unit,
`only one via-hole 112 is needed in the layout pattern.
`Comparing with two layout patterns in FIG. 12B and FIG.
`13B,it can be understoodthat the phase correction circuit 40
`could be reduced in size corresponding to one via-hole.
`As described above, the phase correction circuits 20,30
`and 40 according to the embodiments 1,2 and 3 can stabilize
`the phase shift of the output signal of the transistor 100 by
`maintaining the total capacitance of Cd and C,, in the
`predetermined constant value, even if the supply voltage to
`the gate of the transistor 100 is increased by, for example,
`the function of the temperature compensation circuit 10, so
`that the following circuit using the output signal of the
`transistor 100 can work correctly.
`Whatis claimedis:
`1. A phase correction circuit for a transistor, comprising:
`a circuit element having an output terminal connected to
`a gate of a transistor to which a control signal line is
`connected, and an input terminal, wherein the circuit
`element has a reactance that changes with potential
`difference between the input terminal and the output
`terminal; and
`a voltage control circuit supplying a voltage to the input
`terminal of the circuit element so that the reactance of
`
`8
`the circuit element decreases in response to an increase
`in potential of the gate, wherein a sum of the reactance
`of the circuit element and a gate-source reactance of the
`transistor remains substantially constant.
`2. The phase correction circuit according to claim 1,
`wherein the circuit elementis a diode having an anodeas the
`input terminal and a cathode as the output terminal, the
`cathode of the diode is connectedto the gate of the transistor,
`and the voltage control circuit supplies a reverse bias to the
`anode of the diode.
`3. The phase correction circuit according to claim 1,
`wherein the circuit element
`includes a diode having an
`anode as the inputs terminal and a cathode as the output
`terminal, the cathode being connected directly, or indirectly
`to the gate ofthe transistor, and including a transmission line
`serially connected to one of the anode and cathode of the
`diode, wherein the voltage control circuit supplies a reverse
`bias to the anode of the diode.
`
`10
`
`15
`
`4. The phase correction circuit according to claim 1,
`wherein the circuit element includesfirst and second diodes
`
`20
`
`the cathodes are
`having respective anodes and cathodes,
`connected to each other, the anode of the first diode is the
`output terminal connected to the gate of the transistor and,
`the voltage control circuit supplies a reverse bias to the
`anode of the second diode as the input terminal.
`*
`*
`*
`*
`*
`
`25
`
`11
`
`11
`
`