JP2001244743A - Quadratic function generator and tcxo controller using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a TCXO (temperature compensated crystal oscillation) which is controller so that it can be operated at a low power supply voltage. SOLUTION: The TCXO controller 100, operated at a low-voltage power supply of about 2.0 V, consists of a linear frequency generating circuit 200 to generate currents I210, I210a proportional to a difference between an ambient temperature T and a reference temperature To, a O-the order function generating circuit 300 to generate a fixed current I206a nearly constant with respect to the ambient temperature T, a quadratic function generating circuit 400 that uses the current I210 to generate a current I120 proportional to a square of the difference between the ambient temperature T and the reference temperature To, a controller (adjustment circuit) 500 to adjust the currents I210, I210a, I206a, and I120, a current-voltage conversion resistor 110 that converts a sum of the currents I210a, I206a, and I120 into a control voltage Vin, and a voltage controlled crystal oscillator circuit (VCXO) 600 that controls the oscillated frequency according to the voltage Vin, having a temperature characteristic of a quasi- cubic function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for generating an output current proportional to the square of the difference between the ambient temperature and a reference temperature.
The present invention relates to a quadratic function generator and a TCXO (temperature compensated crystal oscillation) controller using the same.

[0002]

2. Description of the Related Art The free-running oscillation frequency of a crystal oscillation circuit fluctuates greatly with a change in ambient temperature, represented by a substantially cubic function, due to the physical structure of the crystal oscillator. JP 9
JP-A-153104 discloses a TCXO control device for compensating for this variation. According to the publication,
A control function of a cubic function is generated using a cubic function generating circuit for generating an output current proportional to the cube of the difference between the ambient temperature and the reference temperature, and the voltage is used as a voltage-controlled crystal oscillation circuit ( VCXO).

[0003]

In the conventional TCXO control device, when the power supply voltage is low, the cubic function generating circuit does not operate particularly at low temperatures, and the error from the ideal cubic function increases. was there. Specifically, since a current proportional to the difference between the ambient temperature and the reference temperature had to flow through a series circuit of three diodes, the forward voltage of each diode was about 0.7 V.
Considering that only 3V is required, the cubic function generation circuit is 2.4V
The above power supply voltage was required.

An object of the present invention is to realize a TCXO control device operable at a low power supply voltage.

Another object of the present invention is to provide a quadratic function generator suitably used for the TCXO controller.

[0006]

In order to achieve the above object, a TCXO control device according to the present invention uses a zero-order function generation circuit, a first-order function generation circuit, and a quadratic function generation circuit to calculate the output current of each of them. A control voltage having a temperature characteristic of a pseudo cubic function is generated, and the crystal oscillation frequency is controlled according to this voltage. Various forms of the quadratic function generator suitably used in the TCXO control device will be described later. However, by adopting a quadratic function generating circuit instead of the cubic function generating circuit, at least according to a certain form, The power supply voltage is reduced only by the forward voltage of one diode, that is, about 0.7V.

[0007]

FIG. 1 shows an example of the configuration of a quadratic function generator according to the present invention. Quadratic function generator 10 of FIG.
Is for discharging an output current I proportional to the square of the difference between the ambient temperature T and the reference temperature To to the load 12. The cathode side of the first diode D11 is grounded, and the anode side is connected to the ambient temperature. T is connected to a fixed current Io substantially constant with respect to T, its contact is connected to the non-inverting input terminal of the operational amplifier 11, the cathode of the second diode D12 is grounded, and its anode is connected to the third diode. D13 to the cathode side, the anode side of which is connected to the ambient temperature T and the reference temperature To.
, The collector of which is connected to the base of an NPN-type first transistor Q11 whose collector is connected to the power supply Vcc, and the emitter of which is connected to the inverting input terminal of the operational amplifier 11. , A PNP-type second transistor Q1 whose output is connected to the base of the operational amplifier 11
2 and the output current I
Is configured to exhale.

In FIG. 1, a current Io flowing through D11 is a fixed current which is substantially constant with respect to an ambient temperature T, and a current It flowing through D12 and D13 is represented by an ambient temperature T and a reference temperature To.
And it is represented by It = Io × (T−To).

The potential V11 of the anode of D11 is represented by the following equation, where k is the Boltzmann constant, q is the amount of charge of electrons, and Is is the saturation current. V11 = kT / q × ln (Io / Is) The potential V12 of the anode of D13 is expressed as follows: V12 = 2 kT / q × ln (It / Is). Here, assuming that the base-emitter voltage of Q11 is Vbe11, the potential V13 of the emitter of Q12 is V13.
Is Becomes

Here, when the gain of the operational amplifier 11 is high, since negative feedback is applied, it can be considered that the voltage V11 at the non-inverting input terminal is equal to the voltage V13 at the inverting input terminal. Therefore, from V11 = V13, I = Io × (T−To) ² , and the output current I is proportional to the square of the difference between the ambient temperature T and the reference temperature To. Moreover, since the forward voltages of D12 and D13 are each about 0.7 V, the circuit of FIG.
At low voltage Vcc. The configuration of Io and It in the above description will be described later in detail.

FIG. 2 shows another configuration example of the quadratic function generator according to the present invention. The quadratic function generator 20 of FIG.
An output current I proportional to the square of the difference between the ambient temperature T and the reference temperature To is drawn from the load 22 (complementary to FIG. 1). The anode of the first diode D21 is connected to the power supply Vcc. The cathode side is connected to a fixed current Io substantially constant with respect to the ambient temperature T, the contact is connected to the non-inverting input terminal of the operational amplifier 21, and the anode side of the second diode D22 is connected to the power supply Vcc. Then, the cathode side is connected to the anode side of the third diode D23, the cathode side is connected to a current It proportional to the difference between the ambient temperature T and the reference temperature To, and the contact is connected to a collector grounded. Connected to the base of a first PNP-type transistor Q21, the emitter of which is connected to the inverting input terminal of the operational amplifier 21 and the second NPN-type transistor whose output is connected to the base. Connected to the emitter of the transistor Q22, and is configured to draw the output current I by its collector.

In FIG. 2, a current Io flowing through D21 is a fixed current which is substantially constant with respect to the ambient temperature T, and a current It flowing through D22 and D23 is represented by the ambient temperature T and the reference temperature To.
And it is represented by It = Io × (T−To).

The potential V21 of the cathode of D21 is represented by the following equation, where k is Boltzmann's constant, q is the amount of charge of electrons, and Is is the saturation current: V21 = Vcc-kT / q × ln (Io / Is). The potential V22 of the cathode of D23 is expressed as follows: V22 = Vcc-2kT / q × ln (It / Is). Here, assuming that the base-emitter voltage of Q21 is Vbe21, the potential V23 of the emitter of Q22 is V23.
Is Becomes

Here, when the gain of the operational amplifier 21 is high, since negative feedback is applied, it can be considered that the voltage V21 at the non-inverting input terminal is equal to the voltage V23 at the inverting input terminal. Therefore, from V21 = V23, I = Io × (T−To) ² , and the output current I is proportional to the square of the difference between the ambient temperature T and the reference temperature To. Moreover, since the forward voltages of D22 and D23 are each about 0.7 V, even if it is considered that only 0.3 V is required to configure It, the circuit of FIG.
At low voltage Vcc.

FIG. 3 shows still another configuration example of the quadratic function generator according to the present invention. The quadratic function generator 30 of FIG.
Outputs an output current I proportional to the square of the difference between the ambient temperature T and the reference temperature To to the load 32. The other end of the resistor R31 having one end connected to the power supply Vcc is connected to the ambient temperature T.
Is connected to a substantially constant fixed current Io, and its contact is connected to the non-inverting input terminal and the collector of the operational amplifier
c, the emitter is connected to the base of the first transistor Q31 of NPN type, its emitter is connected to a current It proportional to the difference between the ambient temperature T and the reference temperature To, and its contact is grounded. PNP type second transistor Q
32, the emitter of which is connected to the power supply V at one end.
cc is connected to the other end of a fixed current Io which is substantially constant with respect to the ambient temperature T, and its collector is connected to the power supply Vcc.
Is connected to the base of a third transistor Q33 of the NPN type, whose emitter is connected to a current It proportional to the difference between the ambient temperature T and the reference temperature To, and its contact is
PNP type fourth transistor Q having a collector grounded
34, the emitter of which is connected to the operational amplifier 3
1 and an output of the operational amplifier 31 are connected to the emitter of an NPN-type fifth transistor Q35 connected to the base, the collector of which is connected to the power supply Vcc.
Is connected to the base and collector of a PNP-type sixth transistor Q36, and the emitter is connected to a power supply Vcc.
Is connected to the base of a PNP-type seventh transistor Q37 connected to the second transistor Q3, and the output current I is discharged from its collector.

In FIG. 3, the current Io flowing through R31 and the current Io flowing through the emitter of Q32 are fixed currents substantially constant with respect to the ambient temperature T. Current It flowing to the emitter of Q31 and Current It flowing to the emitter of Q33
Is proportional to the difference between the ambient temperature T and the reference temperature To, and is represented by It = Io (T-To).

The potential V31 at the base of Q31 is expressed as follows: V31 = Vcc-Io × R31. The potential V32 at the base of Q32 is
Assuming that the base-emitter voltage of V.31 is Vbe31, k is the Boltzmann constant, q is the amount of charge of electrons, and Is is the saturation current, V32 = V31−Vbe31 = Vcc−Io × R31−kT / q × ln (It / Is). Since the current Io flows through the emitter of Q32, if the base-emitter voltage of Q32 is Vbe32, the potential V33 of the base of Q33 is V33 = V32 + Vbe32 = Vcc-Io * R31-kT / q * ln (It / Is ) + KT / q × ln (Io / Is). Since the current It flows through the emitter of Q33,
Assuming that the base-emitter voltage of Q33 is Vbe33, the potential V34 of the base of Q34 is as follows: V34 = V33-Vbe33 = Vcc-Io * R31-2kT / q * ln (It / Is) + kT / q * ln (Io / Is). The current flowing to the emitter of Q34 is equal to the current flowing to the collector of Q36, and this current is equal to the current I flowing to the collector of Q37. Therefore, if the base-emitter voltage of Q34 is Vbe34, the potential V35 of the emitter of Q35 becomes V35 = V34 + Vbe34 = Vcc-Io * R31-2kT / q * ln (It / Is) + kT / q * In (Io / Is) + kT / q * In (I / Is)

Here, when the gain of the operational amplifier 31 is high, since negative feedback is applied, it can be considered that the voltage V31 at the non-inverting input terminal is equal to the voltage V35 at the inverting input terminal. Therefore, from V31 = V35, I = Io × (T−To) ² , and the output current I is proportional to the square of the difference between the ambient temperature T and the reference temperature To. In addition, for example, Io × R31 = 0.
When R31 is set to be 4V, since Vbe31 is about 0.7V, even if it is considered that only 0.3V is required to configure It, the input side circuit of the operational amplifier 31 in FIG. At low voltage Vcc. However,
Since about 2.0 V is required for the series circuit of Q34, Q35 and Q36, the entire circuit of FIG.
It can work with.

FIG. 4 shows still another configuration example of the quadratic function generator according to the present invention. Quadratic function generator 40 of FIG.
Is a circuit that draws an output current I proportional to the square of the difference between the ambient temperature T and the reference temperature To from the load 42 (complementary to FIG. 3). A PNP-type first transistor Q4, which is connected to a fixed current Io substantially constant with respect to the temperature T, and has its contact point connected to the non-inverting input terminal of the operational amplifier 41 and the collector to the ground.
1 connected to a current It proportional to the difference between the ambient temperature T and the reference temperature To, and its contact is connected to a second power supply of the NPN type having a collector connected to the power supply Vcc.
, The emitter of which is connected to the other end of a fixed current Io having one end grounded and substantially constant with respect to the ambient temperature T, and the contact thereof connected to the third collector of a PNP type grounded collector. Of the transistor Q43, its emitter is connected to a current It proportional to the difference between the ambient temperature T and the reference temperature To, and its contact is connected to a fourth NPN-type collector whose collector is connected to the power supply Vcc. Connected to the base of transistor Q44, the emitter is connected to the inverting input terminal of operational amplifier 41, and the emitter of the fifth PNP transistor Q45 whose output is connected to the base of the operational amplifier 41, and the collector of Q45 is connected. Is connected to the base and the collector of an NPN-type sixth transistor Q46 whose emitter is grounded, and which is connected to an emitter whose ground is grounded.
Connected to the base of a PN-type seventh transistor Q47,
The output current I is drawn by the collector.

In FIG. 4, the current Io flowing through R41 and the current Io flowing through the emitter of Q42 are fixed currents substantially constant with respect to the ambient temperature T. Current It flowing to the emitter of Q41 and Current It flowing to the emitter of Q43
Is proportional to the difference between the ambient temperature T and the reference temperature To, and is expressed by It = Io × (T−To).

The potential V41 at the base of Q41 is expressed as follows: V41 = Io × R41. Also, the base potential V42 of Q42 is Q
Assuming that the base-emitter voltage of 41 is Vbe41, k is Boltzmann's constant, q is the amount of charge of electrons, and Is is the saturation current, V42 = V41 + Vbe41 = Io * R41 + kT / q * ln (It / Is) . Since the current Io flows through the emitter of Q42, assuming that the base-emitter voltage of Q42 is Vbe42, the base potential V43 of Q43 is as follows: V43 = V42−Vbe42 = Io × R41 + kT / q × ln (It / Is) − kT / q × ln (Io / Is). Since the current It flows through the emitter of Q43,
Assuming that the base-emitter voltage of Q43 is Vbe43, the potential V44 of the base of Q44 is as follows: V44 = V43 + Vbe43 = Io × R41 + 2 kT / q × ln (It / Is) −kT / q × ln (Io / Is) The current flowing to the emitter of Q44 is equal to the current flowing to the collector of Q46, and this current is equal to the current I flowing to the collector of Q47. Therefore, if the base-emitter voltage of Q44 is Vbe44, the potential V45 of the emitter of Q45 becomes V45 = V44−Vbe44 = Io × R41 + 2 kT / q × ln (It / Is) −kT / q × ln (Io / Is) −kT / q × ln (I / Is)

Here, when the gain of the operational amplifier 41 is high, since negative feedback is applied, it can be considered that the voltage V41 at the non-inverting input terminal is equal to the voltage V45 at the inverting input terminal. Therefore, from V41 = V45, I = Io × (T−To) ² , and the output current I is proportional to the square of the difference between the ambient temperature T and the reference temperature To. In addition, for example, Io × R41 = 0.
When R41 is set to be 4V, since Vbe41 is about 0.7V, the input side circuit of the operational amplifier 41 in FIG. At low voltage Vcc. However,
Since about 2.0 V is required for the series circuit of Q54, Q55 and Q56, the entire circuit of FIG.
It can work with.

FIG. 5 shows still another configuration example of the quadratic function generator according to the present invention. The quadratic function generator 50 of FIG.
Outputs an output current I proportional to the square of the difference between the ambient temperature T and the reference temperature To to the load 52. The other end of the resistor R51 having one end connected to the power supply Vcc is connected to a diode D
The cathode side is connected to a fixed current Io substantially constant with respect to the ambient temperature T, and the cathode side is connected to the base of a PNP-type first transistor Q51 whose collector is grounded. Connect and connect its emitter,
The emitter is connected to the collector of a PNP-type second transistor Q52 connected to the power supply Vcc, the contact is connected to the non-inverting input terminal of the operational amplifier 51, and the anode of D51 is connected to the NPN-type third transistor. Connected to the base of Q53, the emitter of which is connected to ambient temperature T and reference temperature T.
o, the collector of which is connected to the base of a fourth PNP transistor Q54 whose collector is grounded, and whose emitter is connected to a fifth PNP transistor whose emitter is connected to the power supply Vcc. Of the transistor Q55, and the base of an NPN-type sixth transistor Q56 whose collector is connected to the power supply Vcc.
PNP whose emitter is connected to the power supply Vcc
PNP connected to the collector and base of a seventh transistor Q57 of the same type and having the emitter connected to the power supply Vcc
NPN-type transistor Q58 having a collector connected to the base and the emitter of a ninth transistor Q59 of an NPN type having a grounded emitter and a collector connected to the base of an eighth transistor Q58 having a grounded emitter. Q
60, the collector of which is connected to the emitter of Q56, and the collector of which is grounded.
1 is connected to the base of the transistor Q61, its emitter is connected to the inverting input terminal of the operational amplifier 51, and its base is connected to the output of the operational amplifier 51.
And the collector of the transistor Q62, the emitter of which is connected to the base and collector of a thirteenth PNP-type transistor Q63 whose emitter is connected to the power supply Vcc, and the base of Q52, and the base of Q55. And an emitter connected to the base of a PNP-type fourteenth transistor Q64 connected to the power supply Vcc, so as to discharge the output current I from its collector.

In FIG. 5, the current Io flowing through D51 is a fixed current which is substantially constant with respect to the ambient temperature T, and the current It flowing through the emitter of Q53 is the ambient temperature T and the reference temperature To.
And it is represented by It = Io × (T−To).

The potential V51 of the anode of D51 is represented by the following equation: V51 = Vcc-Io × R51. Further, the potential V52 of the emitter of the transistor Q53 is determined by setting the base-emitter voltage of the transistor Q53 to Vbe.
53, k is Boltzmann's constant, q is the amount of electron charge, I
When s is a saturation current, V52 = V51−Vbe53 = Vcc−Io × R51−kT / q × ln (It / Is). The current flowing through the emitter of Q54 is Q55
Since this current is equal to the current I flowing to the collector of Q64, if the base-emitter voltage of Q54 is Vbe54, the potential V53 of the emitter of Q54 is V53 = V52 + Vbe54 = Vcc-Io × R51−kT / q × ln (It / Is) + kT / q × ln (I / Is) The current flowing to the emitter of Q56 is equal to the current flowing to the collector of Q60, this current is equal to the current flowing to the collector of Q59, this current is equal to the current flowing to the collector of Q57, and this current is the current flowing to the emitter of Q53. Since it is equal to It, assuming that the base-emitter voltage of Q56 is Vbe56, the potential V54 of the emitter of Q56 is as follows: V54 = V53−Vbe56 = Vcc−Io × R51-2kT / q × ln (It / Is) + kT / q × ln (I / Is). The current flowing to the emitter of Q61 is equal to the current flowing to the collector of Q63, and this current is equal to the current I flowing to the collector of Q64. Therefore, if the base-emitter voltage of Q61 is Vbe61, the potential V55 of the emitter of Q61 becomes V55 = V54 + Vbe61 = Vcc-Io * R51-2kT / q * ln (It / Is) + 2kT / q * ln (I / Is)

On the other hand, the potential V56 of the cathode of D51 is as follows: V56 = Vcc-Io * R51-kT / q * ln (Io
/ Is). The current flowing to the emitter of Q51 is equal to the current flowing to the collector of Q52, and this current is equal to the current I flowing to the collector of Q64. Therefore, when the base-emitter voltage of Q51 is Vbe51, the potential V57 of the emitter of Q51 becomes V57 = V56 + Vbe51 = Vcc−Io × R51−kT / q × ln (Io / Is) + kT / q × ln (I / Is)

Here, when the gain of the operational amplifier 51 is high, since negative feedback is applied, it can be considered that the voltage V57 at the non-inverting input terminal is equal to the voltage V55 at the inverting input terminal. Therefore, from V55 = V57, I = Io × (T−To) ² , and the output current I is proportional to the square of the difference between the ambient temperature T and the reference temperature To. In addition, for example, Io × R51 = 0.
When R51 is set to be 4V, since Vbe53 is about 0.7V, the input side circuit of operational amplifier 51 in FIG. At low voltage Vcc. However,
Since about 2.0 V is required for the series circuit of Q61, Q62 and Q63, the entire circuit of FIG.
It can work with.

FIG. 6 shows still another configuration example of the quadratic function generator according to the present invention. Quadratic function generator 70 of FIG.
Is a circuit for drawing an output current I proportional to the square of the difference between the ambient temperature T and the reference temperature To from the load 72 (complementary to FIG. 5), and connecting the other end of the resistor R71 having one end grounded to the diode D71. NP, whose anode is connected to a fixed current Io substantially constant with respect to the ambient temperature T, and whose contact is connected to the collector of the power supply Vcc.
Connected to the base of an N-type first transistor Q71, the emitter of which is connected to the collector of an NPN-type second transistor Q72 whose emitter is grounded, and to the non-inverting input terminal of the operational amplifier 71; The cathode of D71 is connected to the base of a third transistor Q73 of the PNP type, the emitter is connected to a current It proportional to the difference between the ambient temperature T and the reference temperature To, and the collector is connected to the power supply Vc.
c, the collector of an NPN-type fifth transistor Q75 whose emitter is connected to the base of the fourth transistor Q74, the emitter of which is connected to the base of the fourth transistor Q74.
PNP-type sixth transistor Q having a collector grounded
The collector of Q73 is connected to the collector and base of an NPN-type seventh transistor Q77 whose emitter is grounded, and the base of an NPN-type eighth transistor Q78 whose emitter is grounded. The collector is connected to the collector and base of a ninth transistor Q79 of the PNP type whose emitter is connected to the power supply Vcc, and the collector is connected to the base of a tenth transistor Q80 of the PNP type whose emitter is connected to the power supply Vcc. The collector is connected to the emitter of Q76, the collector is connected to the base of an eleventh transistor Q81 of the PNP type connected to the power supply Vcc, the emitter is connected to the inverting input terminal of the operational amplifier 71, And a PNP-type twelfth transistor Q82 having a base connected to the output of the operational amplifier 71. Connected to emitter, the collector is connected to the base and collector of the 13th transistor Q83 of NPN type whose emitter is grounded, and Q72
The base of the transistor Q75 and the base of an NPN-type fourteenth transistor Q84 whose emitter is grounded are connected to each other, and the collector of the transistor Q84 draws the output current I.

In FIG. 6, the current Io flowing through D71 is a fixed current which is substantially constant with respect to the ambient temperature T, and the current It flowing through the emitter of Q73 is between the ambient temperature T and the reference temperature To.
And it is represented by It = Io × (T−To).

The potential V71 of the cathode of D71 is expressed as follows: V71 = Io × R71 Further, the potential V72 of the emitter of the transistor Q73 is equal to the base-emitter voltage of the transistor Q73 being Vbe.
73, k is Boltzmann's constant, q is the amount of electron charge, I
If s is a saturation current, V72 = V71 + Vbe73 = Io × R71 + kT / q × ln (It / Is). The current flowing through the emitter of Q74 is Q75
Since this current is equal to the current I flowing to the collector of Q84, if the base-emitter voltage of Q74 is Vbe74, the potential V73 of the emitter of Q74 becomes V73 = V72−Vbe74 = Io × R71 + kT / q × ln (It / Is) −kT / q × ln (I / Is) The current flowing to the emitter of Q76 is equal to the current flowing to the collector of Q80, this current is equal to the current flowing to the collector of Q79, this current is equal to the current flowing to the collector of Q77, and this current is the current flowing to the emitter of Q73. Since it is equal to It, assuming that the base-emitter voltage of Q76 is Vbe76, the potential V74 of the emitter of Q76 is given by: Is). The current flowing through the emitter of Q81 is equal to the current flowing through the collector of Q83, and this current is equal to the current I flowing through the collector of Q84. Therefore, when the base-emitter voltage of Q81 is Vbe81, the potential V75 of the emitter of Q81 becomes V75 = V74−Vbe81 = Io × R71 + 2 kT / q × ln (It / Is) −2 kT / q × ln (I / Is)

On the other hand, the potential V76 of the anode of D71 is as follows: V76 = Io × R71 + kT / q × ln (Io / Is) The current flowing to the emitter of Q71 is equal to the current flowing to the collector of Q72, and this current is equal to the current I flowing to the collector of transistor Q84.
Assuming that the base-emitter voltage of Vbe71 is Vbe71, Q7
The potential V77 of the emitter 1 is as follows: V77 = V76−Vbe71 = Io × R71 + kT / q × ln (Io / Is) −kT / q × In (I / Is)

Here, when the gain of the operational amplifier 71 is high, since negative feedback is applied, it can be considered that the voltage V77 at the non-inverting input terminal is equal to the voltage V75 at the inverting input terminal. Therefore, from V75 = V77, I = Io × (T−To) ² , and the output current I is proportional to the square of the difference between the ambient temperature T and the reference temperature To. In addition, for example, Io × R71 = 0.
When R71 is set to 4 V, since Vbe73 is about 0.7 V, the input side circuit of the operational amplifier 71 in FIG. At low voltage Vcc. However,
Since about 2.0 V is required for the series circuit of Q81, Q82 and Q83, the entire circuit of FIG.
It can work with.

FIG. 7 shows a configuration example of a TCXO control device according to the present invention. TCXO control device 100 of FIG.
Is a current I proportional to the difference between the ambient temperature T and the reference temperature To.
A first-order function generating circuit 200 for generating the first and second constant currents I2 and I210a;
06a, a zero-order function generation circuit 300 for generating
210, the difference between the ambient temperature T and the reference temperature To
Quadratic function generation circuit 400 for generating current I120 proportional to the power, and controller (adjustment circuit) for adjusting I210, I210a, I206a, and I120
500 and a current-voltage conversion resistor 1 for converting the sum of I210a, I206a and I120 into a control voltage Vin.
10 and a voltage-controlled crystal oscillation circuit (VCXO) 600 for controlling the oscillation frequency according to Vin, and can be operated with a low-voltage power supply of about 2.0 V.

FIG. 8 is a circuit diagram of the linear function generating circuit 200 shown in FIG.
3 shows an example of the detailed configuration. This linear function generating circuit 20
0 indicates four blocks, that is, a bandgap type current / voltage generation circuit 220, a first current supply circuit 240, and a second
, And a third current supply circuit 280.

FIG. 9 shows a detailed configuration example of the bandgap type current / voltage generating circuit 220 in FIG. The circuit shown in FIG. 9 outputs a voltage Vt that is substantially constant with respect to the ambient temperature T. The circuit shown in FIG.
22 and two NPN transistors 223, 224
And two resistors 225 and 226. One NPN transistor 223 has a size n times as large as that of the other NPN transistor 224. This circuit adjusts Vt to 1.2 V, so that the transistor 22
It can operate at a low voltage Vcc of 1.5 V by adding a saturation voltage of 2 (0.3 V).

FIG. 10 shows the first current supply circuit 2 shown in FIG.
40 shows an example of a detailed configuration. The circuit of FIG. 10 receives the voltage Vt and the 4-bit adjustment signal To from the controller 500, and outputs currents I206, I216, and I252 that are substantially constant with respect to the ambient temperature T. , An operational amplifier 241, three NPN transistors 242, 250, 251 and one resistor 243.
And three PNP transistors 244, 248, 24
9 is provided. Further, in the circuit of FIG. 10, the base voltage V
four PNP transistors 245 sharing bc,
Four PNP transistors 246 each having a base-collector directly connected, and four NP transistors for switching.
And an N-type transistor 247.

According to the circuit of FIG.
Is subjected to voltage-current conversion. Assuming that this current is I242, I242 = Vt / R243, and when the resistor 243 is a resistor having a substantially constant temperature characteristic with respect to the ambient temperature T, the I242 becomes a substantially constant current with respect to the ambient temperature T. Therefore, Vbc is substantially constant with respect to the ambient temperature T. The discharge current I206 is
Equal to the collector current of transistor 249, which is the collector current of transistor 244, i.e., I242
be equivalent to. I216 sets the collector current of transistor 248 equal to I206 to transistors 250 and 251
And the current mirror circuit is configured to invert the current into a drawn current, and I216 = -I206 holds. The current I252 is also substantially constant with respect to the ambient temperature T, and the magnitude of the current is determined according to the To adjustment bit (four bits in FIG. 10).
7 are minimum when all four base voltages are H, and maximum when all are low. As shown in FIG.
52 is an output current I 210 of the second current supply circuit 260
To be adjusted.

FIG. 11 shows the second current supply circuit 2 shown in FIG.
60 shows a detailed configuration example. The circuit of FIG. 11 receives the base voltage Vbc and the 4-bit adjustment signal A from the controller 500 and outputs a current I210 proportional to the difference between the ambient temperature T and the reference temperature To. Corresponding to the 4-bit signal A, four PNP transistors 261 sharing Vbc,
Four PNP transistors 2 whose collectors are directly connected
62, and four NPN transistors 263 for switching. Further, the circuit of FIG.
NPN transistors 264, 265, 266,
Two PNP transistors 267, 268, three resistors 269, 270, 271 and a resistance adjusting circuit 276
And The resistance value adjustment circuit 276 includes two resistors 272 and 273 and two zener diodes 274 and
75.

According to the circuit of FIG.
The current I264 flowing into the collector of
Similarly, the current is substantially constant with respect to the ambient temperature T,
It is determined according to the A adjustment bit (four bits in FIG. 11), and becomes minimum when all four base voltages of the transistor 263 are H, and becomes maximum when all are L. This current I
264 is input to the current mirror circuit, and outputs a current I210 proportional to the difference between the ambient temperature T and the reference temperature To.

More specifically, since the current flowing through the resistor 269 is I264, the current I265 flowing through the collector of the transistor 265 is equal to that of the transistors 264 and 265.
Neglecting the difference in base-emitter voltage of
The resistance values of 69 and 270 are set to R269 and R27, respectively.
When it is set to 0, I265 = I264 × R269 / R270
Becomes The resistors 269 and 270 and the resistors 271 and 272
And 273 are resistors having different temperature characteristics. The former primary temperature coefficient is α1, the secondary temperature coefficient is β1, the latter primary temperature coefficient is α2, and the secondary temperature coefficient is β2, R0.269, R0.2 at the reference temperature To
When expressed as 70, R0.271, R0.272 and R0.273, I265 = I264 × R0.269 (1 + α1 (T−To) + β1 (T−To) ² ) /R0.270 (1 + α1 (T−To)) + Β1 (T−To) ² ) = I264 × R0.269 / R0.270 Further, assuming that the resistance value of the resistor 271 is R271, the current I266 flowing through the collector of the transistor 266 is I266 = I264 × R269 / R271 = I264 × R0.269 (1 + α1 (T−To) + β1 (T−To) ² ) /R0.271 ( ¹ + α2 (T-To) + β2 (T-To) ² ). When α1 and β1 are small and β2 is negligible, I266 = I264 × R0.269 / R0.271 (1
+ Α2 (T−To)).

Here, the resistance value adjusting circuit 276 will be described. When a resistance having a first temperature characteristic and a resistance having a second temperature characteristic are diffused and formed on a semiconductor integrated circuit, the method of manufacturing the resistance of the first temperature characteristic and the method of manufacturing the resistance of the second temperature characteristic are usually different from each other. However, even with the same mask pattern, the values of both resistors may be different. Therefore, the resistance 2 of the second temperature characteristic
71, 272, 273 are prepared, these resistors are connected in parallel, and the electrode P3 is connected to the junction of the resistors 271, 272, 273.
The electrode P1 is connected to the other end of the resistor 272, and the electrode P2 is connected to the other end of the resistor 273. The resistance value between the electrode P3 and the ground can be measured by a measuring device connected to the outside. Zener diodes 274 and 275 are connected to the resistors 272 and 273, and the path between each resistor and the ground is cut off in the initial state. Electrode P1 or P
When a short-circuit path is provided in the Zener diodes 274 and 275 by applying a voltage or current between the resistor 2 and the ground, the resistor 271 can be connected to the resistor 272 or 273 in parallel. The value can approximately match the value of resistor 270. In this way, two types of resistors having different temperature characteristics but substantially equal resistance values can be provided on the semiconductor integrated circuit.

Using the resistance adjusting circuit 276, it can be considered that R0.270 = R0.271, and the collector current I268 of the transistor 268 becomes the collector current I2 of the transistor 267.
65, so when α2 is sufficiently small, I210 = I268−I266 = I264 × R0.269 / R0.270 × (1-1 / (1 + α2 (T−To)) ≒ I264 × R0.269 / R0. 270 × α2 (T−To), and I210 is proportional to the difference between the ambient temperature T and the reference temperature To.

FIG. 12 shows the third current supply circuit 2 shown in FIG.
80 shows a detailed configuration example. The circuit of FIG. 12 receives the base voltage Vbc and the 4-bit adjustment signal B from the controller 500 and outputs a current I210a proportional to the difference between the ambient temperature T and the reference temperature To. In response to the 4-bit signal B, four PNP transistors 281 sharing Vbc, four PNP transistors 282 each having a base-collector directly connected, and four NPN transistors for switching. And a type transistor 283. Further, the circuit of FIG.
Three NPN transistors 284, 285, 286
, Two PNP transistors 287, 288, 3
Resistors 289, 290, 291 and resistance adjustment circuit 2
96. The resistance adjustment circuit 296 includes two resistors 292 and 293 and two zener diodes 29.
4,295. P4, P5 and P6 are resistance value adjusting electrodes.

According to the circuit of FIG. 12, similarly to the circuit of FIG. 11, the current I flowing into the collector of transistor 284
284 is a substantially constant current with respect to the ambient temperature T,
It is determined according to the B adjustment bit (4 bits in FIG. 12), and becomes minimum when all four base voltages of the transistor 283 are H, and becomes maximum when all L are L. The resistances 289 and 290 and the resistances 291, 292 and 293 have different temperature characteristics, and a current I210a is generated from I284 by a current mirror circuit in proportion to the difference between the ambient temperature T and the reference temperature To.

FIG. 13 shows a zero-order function generating circuit 30 in FIG.
0 shows a detailed configuration example. This zero-order function generation circuit 3
Reference numeral 00 denotes the input of the base voltage Vbc and the input of a 4-bit adjustment signal C from the controller 500 to output a fixed current I206a substantially constant with respect to the ambient temperature T. In response to the above, there are provided four PNP transistors 301 sharing Vbc, four PNP transistors 302 each having a base-collector directly connected, and four NPN transistors 303 for switching. ing.

According to the circuit of FIG. 13, I206a is a substantially constant current with respect to the ambient temperature T, is determined according to the C adjustment bit (four bits in FIG. 13), and has four bases of the transistor 303. When the voltages are all H, the voltage becomes minimum, and when the voltages are all L, the voltage becomes maximum. The first to third current supply circuits 240, 260, 280 and the zero-order function generation circuit 300 can operate at a low voltage Vcc of 1.7V.

FIG. 14 shows the quadratic function generation circuit 40 shown in FIG.
0 shows a detailed configuration example. This quadratic function generation circuit 4
00 is a combination of the quadratic function generator 50 of FIG. 5 and the quadratic function generator 70 of FIG.
6, I216 and I210, and outputs a current I120 proportional to the square of the difference between the ambient temperature T and the reference temperature To. Here, I206 and I216 correspond to Io, I21
0 corresponds to It respectively. As described above, the quadratic function generators 50 and 70 can operate at a low voltage Vcc of about 2.0V.

FIG. 15 shows a detailed configuration example of the controller 500 in FIG. This controller 500
PROM (Programmable Read Only Memory) 50
1 and a shift register 502 composed of 16 D flip-flops. According to this example, a serial data signal is input from the DATA terminal while synchronizing with the clock signal of the CLK terminal, the states of the A, B, C, and To adjustment bit signals are determined, and this is written to the PROM 501. Can be. That is, the currents I210a and I2a are changed according to the data signal input to the controller 500.
06a and I120 change, and the current-voltage conversion resistance 11
0, the control voltage V having a desired pseudo cubic function characteristic
in can be generated (see FIG. 7). At this time, the control voltage V
in can be approximately expressed as Vin = −α (T−Ti) ³ + β (T−Ti) + γ, and A, B, C, and To adjustment bits correspond to α, β, γ, and Ti, respectively. I do.

FIG. 16 shows a detailed configuration example of the voltage-controlled crystal oscillation circuit 600 in FIG. This circuit is a Colpitts type oscillation circuit, which includes a varicap diode 601, a crystal oscillator 602, and four resistors 603, 6
04, 608, 609 and two capacitors 605, 6
, An NPN transistor 607, one coupling capacitor 610, and a constant voltage source 611. In this circuit, the capacitance of the varicap diode 601 changes according to the control voltage Vin, and the oscillation frequency changes. That is, the temperature compensation of the crystal oscillation frequency can be realized by applying the control voltage Vin having the temperature characteristic of the pseudo cubic function so as to cancel the temperature characteristic of the Colpitts type oscillation circuit. Although the OSC output is derived from the collector of the transistor 607 in the example of FIG. 16, the OSC output may be derived from the emitter of the transistor 607.

FIGS. 17A to 17E show temperature characteristics of voltage and current at each node in FIG. FIG.
As shown in (a), the current I206 discharged from the first-order function generation circuit 100 and the current I206a discharged from the zero-order function generation circuit 200 are both substantially constant (positive) fixed currents with respect to the ambient temperature T. It is. As shown in FIG. 17B, the current I216 drawn by the linear function generation circuit 100
Is a substantially constant (negative) fixed current with respect to the ambient temperature T. As shown in FIG. 17C, the primary function generation circuit 10
Currents I210 and I2 at which 0 is discharged or drawn
10a is proportional to the difference between the ambient temperature T and the reference temperature To. Also, as shown in FIG. 17D, the current I120 that the quadratic function generation circuit 300
Is proportional to the square of the difference between the ambient temperature T and the reference temperature To. As a result, the control voltage Vin generated from the sum of I206a, I210a, and I120 has a temperature characteristic of a pseudo cubic function, as shown in FIG.

The quadratic function generator 300 shown in FIG. 7 is a combination of the quadratic function generator 10 shown in FIG. 1 and the quadratic function generator 20 shown in FIG. It is also possible to employ a combination of 30 and the quadratic function generator 40 of FIG.

[0052]

As described above, according to the present invention, the temperature characteristic of the pseudo cubic function is obtained from the output currents of the zero-order function generator, the linear function generator, and the quadratic function generator. Is generated, and the crystal oscillation frequency is controlled in accordance with this voltage. Therefore, a TCXO control device operable with a low power supply voltage can be realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of a quadratic function generator according to the present invention.

FIG. 2 is a circuit diagram showing another configuration example of the quadratic function generator according to the present invention.

FIG. 3 is a circuit diagram showing still another configuration example of the quadratic function generator according to the present invention.

FIG. 4 is a circuit diagram showing still another configuration example of the quadratic function generator according to the present invention.

FIG. 5 is a circuit diagram showing still another configuration example of the quadratic function generator according to the present invention.

FIG. 6 is a circuit diagram showing still another configuration example of the quadratic function generator according to the present invention.

FIG. 7 is a block diagram illustrating a configuration example of a TCXO control device according to the present invention.

8 is a block diagram illustrating a detailed configuration example of a linear function generation circuit in FIG. 7;

9 is a circuit diagram showing a detailed configuration example of a bandgap type current / voltage generation circuit in FIG. 8;

FIG. 10 is a circuit diagram illustrating a detailed configuration example of a first current supply circuit in FIG. 8;

FIG. 11 is a circuit diagram showing a detailed configuration example of a second current supply circuit in FIG. 8;

FIG. 12 is a circuit diagram illustrating a detailed configuration example of a third current supply circuit in FIG. 8;

13 is a circuit diagram illustrating a detailed configuration example of a zero-order function generation circuit in FIG. 7;

14 is a circuit diagram showing a detailed configuration example of a quadratic function generation circuit in FIG. 7;

FIG. 15 is a circuit diagram illustrating a detailed configuration example of a controller in FIG. 7;

FIG. 16 is a circuit diagram showing a detailed configuration example of the voltage-controlled crystal oscillation circuit in FIG. 7;

17 is a temperature characteristic diagram of voltage and current at each node in FIG. 7;

[Explanation of symbols]

 10, 20, 30, 40, 50, 70 Quadratic function generator 100 TCXO controller 110 Current-voltage conversion resistor 200 Primary function generation circuit 300 Zero-order function generation circuit 400 Quadratic function generation circuit 500 Controller (adjustment circuit) 600 Voltage Controlled Crystal Oscillator (VCXO)

Claims (8)

[Claims] 1. A quadratic function generator for generating an output current proportional to a square of a difference between an ambient temperature and a reference temperature, wherein a cathode side of a first diode is grounded, and an anode side of the first diode is grounded. Connected to a fixed current that is substantially constant with respect to the ambient temperature, the contact is connected to the non-inverting input terminal of the operational amplifier, the cathode side of the second diode is grounded, and the anode side is
A third diode is connected to the cathode side, its anode side is connected to a current proportional to the difference between the ambient temperature and the reference temperature, and its contact is connected to a first conductive type first terminal whose collector is connected to a power supply. Connected to the base of the transistor, the emitter of which is connected to the inverting input terminal of the operational amplifier and the emitter of the second transistor of the second conductivity type, the output of which is connected to the base; A quadratic function generator for discharging the output current. 2. A quadratic function generator for generating an output current proportional to the square of a difference between an ambient temperature and a reference temperature, wherein an anode of a first diode is connected to a power supply, and a cathode of the first diode is connected to a power supply. Side to a fixed current that is substantially constant with respect to the ambient temperature, and its contact is connected to the non-inverting input terminal of the operational amplifier,
Connecting the anode side of the second diode to the power supply, connecting its cathode side to the anode side of the third diode,
The cathode side is connected to a current proportional to the difference between the ambient temperature and the reference temperature, and its contact is connected to a second electrode whose collector is grounded.
Connected to the base of a first transistor of the conductivity type, the emitter of which is connected to the inverting input terminal of the operational amplifier and the emitter of the second transistor of the first conductivity type, the output of which is connected to the base. A second-order function generator, wherein the output current is drawn by its collector. 3. A quadratic function generator for generating an output current proportional to a square of a difference between an ambient temperature and a reference temperature, wherein the other end of a resistor having one end connected to a power supply is connected to the ambient temperature. And a non-inverting input terminal of the operational amplifier and a base of a first transistor of a first conductivity type having a collector connected to a power supply, and an emitter connected to an ambient temperature. And a current proportional to the difference between the first and second reference types, and the contact is connected to a second conductive type second electrode whose collector is grounded.
, The emitter of which is connected at one end to the other end of a fixed current substantially constant with respect to the ambient temperature connected to the power supply, and the contact of which is connected to the collector at the first conductivity type. , The emitter of which is connected to a current proportional to the difference between the ambient temperature and the reference temperature, and the contact of which is connected to the collector of a fourth transistor of the second conductivity type, the collector of which is grounded. And an emitter connected to an inverting input terminal of the operational amplifier and an emitter of a fifth transistor of the first conductivity type having an output connected to the base, and a collector connected to the emitter. The emitter is connected to the base and collector of the sixth transistor of the second conductivity type connected to the power supply, and the emitter is connected to the base of the seventh transistor of the second conductivity type connected to the power supply. Quadratic function generator, characterized in that discharges the output current from the collector. 4. A quadratic function generator for generating an output current proportional to the square of a difference between an ambient temperature and a reference temperature, wherein the other end of a resistor having one end grounded is connected to the other end with respect to the ambient temperature. The transistor is connected to a substantially constant fixed current, and its contact is connected to the non-inverting input terminal of the operational amplifier and the base of the first transistor of the second conductivity type whose collector is grounded. And a collector connected to the base of a second transistor of the first conductivity type, the collector of which is connected to the power supply, and the emitter connected to an ambient temperature having one end grounded. The other end of the fixed current is connected, the contact is connected to the base of the third transistor of the second conductivity type whose collector is grounded, and the emitter is connected to
Connect a current proportional to the difference between the ambient temperature and the reference temperature, connect its contact to the base of a fourth transistor of the first conductivity type whose collector is connected to the power supply, and connect its emitter to
The inverting input terminal of the operational amplifier is connected to the emitter of a fifth transistor of the second conductivity type, the output of which is connected to the base, and the collector of the fifth transistor is grounded. The first transistor is connected to the base and collector of a sixth transistor of the first conductivity type, and the emitter is connected to the base of a seventh transistor of the first conductivity type grounded, and the collector draws the output current. Quadratic function generator. 5. A quadratic function generator for generating an output current proportional to a square of a difference between an ambient temperature and a reference temperature, wherein the other end of a resistor having one end connected to a power supply is connected to an anode of a diode. , The cathode side of which is connected to a fixed current substantially constant with respect to the ambient temperature, the cathode side contact is connected to the base of a first transistor of the second conductivity type whose collector is grounded, and the emitter is connected to Is connected to the collector of a second transistor of the second conductivity type whose emitter is connected to the power supply, and the contact is connected to the non-inverting input terminal of the operational amplifier, and the anode side of the diode is connected to the first conductivity type. Connected to the base of a third transistor, having its emitter connected to a current proportional to the difference between the ambient temperature and the reference temperature, and connected to the base of a fourth transistor of the second conductivity type having a collector grounded. Connecting the emitter to the collector of a fifth transistor of the second conductivity type, the emitter of which is connected to the power supply, and the base of the sixth transistor of the first conductivity type, the collector of which is connected to the power supply; Connected to the collector and base of a seventh transistor of the second conductivity type, the emitter of which is connected to the power supply,
An emitter is connected to the base of an eighth transistor of the second conductivity type connected to the power supply, the collector is connected to the collector and base of a ninth transistor of the first conductivity type whose emitter is grounded, and the emitter is Is grounded first
A collector connected to the base of a tenth transistor of the conductivity type, a collector connected to the emitter of the sixth transistor, and a collector connected to the base of an eleventh transistor of the second conductivity type having a grounded collector; Is connected to the inverting input terminal of the operational amplifier, and the base is connected to the emitter of a twelfth transistor of the first conductivity type connected to the output of the operational amplifier, and the collector is connected to the power supply. A second conductivity type connected to the base and collector of a thirteenth transistor of the second conductivity type, connected to the base of the second transistor, and having a base and an emitter connected to a power supply of the fifth transistor; A second-order function generator connected to the base of the fourteenth transistor, and discharging the output current from the collector thereof. 6. A quadratic function generator for generating an output current proportional to the square of a difference between an ambient temperature and a reference temperature, wherein one end of a resistor having one end grounded and the other end connected to a cathode side of a diode. Connecting the anode side to a fixed current that is substantially constant with respect to the ambient temperature, connecting its contact to the base of a first transistor of a first conductivity type whose collector is connected to a power supply,
Its emitter is connected to the collector of a second transistor of the first conductivity type whose emitter is grounded and to the non-inverting input terminal of the operational amplifier, and the cathode side of the diode is connected to the third transistor of the second conductivity type. Connecting to the base of the transistor, connecting its emitter to a current proportional to the difference between the ambient temperature and the reference temperature, and connecting the collector to the base of a fourth transistor of the first conductivity type connected to the power supply; The emitter is connected to the collector of a fifth transistor of the first conductivity type whose emitter is grounded, and the second transistor whose collector is grounded.
The collector of the third transistor is connected to the collector and base of a seventh transistor of the first conductivity type, the emitter of which is connected to the base of a sixth transistor of the conductivity type, and the emitter is grounded. Eighth of the first conductivity type
, The collector of which is connected to the collector and base of a ninth transistor of the second conductivity type whose emitter is connected to the power supply, and the tenth transistor of the second conductivity type whose emitter is connected to the power supply. , The collector of which is connected to the emitter of the sixth transistor, and the collector of which is connected to the base of an eleventh transistor of the second conductivity type which is connected to the power supply, and the emitter of which is connected to the arithmetic operation. Connect to the inverting input terminal of the amplifier,
And a base connected to the emitter of the twelfth transistor of the second conductivity type connected to the output of the operational amplifier, and having a collector connected to the thirteenth transistor of the first conductivity type whose emitter is grounded.
Connected to the base and collector of the second transistor, and connected to the base of the second transistor;
And the first transistor whose emitter is grounded
A quadratic function generator, which is connected to a base of a fourteenth transistor of a conductivity type and draws the output current by a collector thereof. 7. A zero-order function generating circuit for generating a fixed current substantially constant with respect to an ambient temperature, and a linear function generating circuit for generating a current proportional to a difference between the ambient temperature and a reference temperature. A quadratic function generation circuit for generating a current proportional to the square of the difference between the ambient temperature and the reference temperature; and each of the zero-order function generation circuit, the linear function generation circuit, and the quadratic function generation circuit A controller for adjusting an output current of: a means for converting a sum of output currents of the zero-order function generation circuit, the first-order function generation circuit, and the second-order function generation circuit into a voltage; A TCXO control device, comprising: a voltage-controlled crystal oscillation circuit for controlling an oscillation frequency in accordance with the voltage obtained by the method. 8. The TCXO control device according to claim 7, wherein the quadratic function generation circuit includes the quadratic function generator according to any one of claims 1 to 6.
CXO controller.