JPH03104403A - Oscillator - Google Patents

Abstract

PURPOSE:To avoid fluctuation of oscillation output power to both a temperature change and a power voltage change by providing a resistor circuit being an emitter resistor of an oscillation transistor(TR) having a temperature characteristic and a TR circuit having a reference voltage and applying a current feedback to control a collector current of the oscillation TR. CONSTITUTION:The oscillation circuit section consists of an oscillation TR 1 and load circuits 2, 3. A collector current of the TR 1 flows so that a voltage generated in a resistance circuit 4 is equal to a reference voltage in a TR circuit 5. The reference voltage in this case is a base-emitter voltage of a TR 12 and constant independently of a change in a power supply voltage and a collector current Ic of the TR 1 is also constant. On the other hand, the reference voltage has a temperature characteristic varying with a temperature change, but the resistance circuit 4 has a temperature characteristic to cancel the temperature characteristic of the reference voltage of the TR circuit 5, then there is no relative change between the reference voltage and the voltage generated in the resistance circuit 4 even in the presence of the temperature change and then the collector current Ic of the TR 1 is unchanged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an oscillator, and more particularly to an oscillator having an oscillation circuit section consisting of a transistor and a load circuit connected to the transistor.

In order to construct a stable wireless system, it is necessary that the electrical characteristics of each unit constituting the wireless system be stable. Therefore, above Yu. The oscillator, which is a local oscillator, is also required to have stable oscillation output power against changes in temperature and power supply voltage.

[Conventional technology]

FIG. 7 shows a configuration diagram of an example of a conventional oscillator.

In the figure, 21 is an NPN transistor which is an oscillation element.
Its collector is grounded. Reference numeral 22 denotes a load circuit that determines the oscillation conditions, and is composed of, for example, a stub formed by a microstrip line, and exhibits capacitive or inductive impedance depending on the line length.

23 is a load circuit that determines the oscillation frequency, for example, a dielectric resonator (OR) and a microstrip line (load circuit 2
2) are magnetically coupled to each other in a circuit configuration. Note that when this oscillator is an electrically controlled oscillator, a varactor sub-resonant circuit is further magnetically coupled to the load circuit 23.

The connection point between the emitter of the transistor 21 and the load circuit 22 is connected to the power supply voltage -■ through a coil 24 and a resistor 25 in series.
Co and one end of the thermistor 26, respectively.

The connection point between the base of the transistor 21 and the load circuit 23 is grounded through a coil 27 and a resistor 28 in series,
It is connected to the other end of the thermistor 26 via a coil 27. This oscillator includes an oscillation circuit section including a transistor 21, load circuits 22 and 23, and resistors 25, 28, . coil 2
4.27 and a bias circuit for the transistor 21 using a thermistor 26.

In this oscillator, a transistor 21 and a load circuit 2
2 indicates a negative resistance, and a signal from the load circuit 23 is input to the base of the transistor 21, where it is amplified and then reflected back toward the load circuit 23, causing microwave oscillation n@. At this time, the base of the transistor 21
The collector current 1c of the transistor 21 flows so that the sum of the emitter voltage VBE and the voltage ■ε generated in the resistor 25 becomes equal to the voltage generated in the thermistor 26, and the collector-emitter voltage of the transistor 21 flows. An oscillation output power Po is generated which is proportional to the product of VCE and collector current IC.

This oscillation output power PO is taken out from the load circuit 23, for example.

FIGS. 8A and 8B show the temperature characteristics and power supply voltage characteristics of the conventional oscillator shown in FIG. 7, respectively.

In general, the BE of the transistor 21 has a temperature coefficient of about -2 mV/''C. Therefore, in this conventional oscillator, when the temperature rises, the oscillation output power PO tends to decrease, but the thermistor 26 By canceling the temperature coefficient of VBE, the collector current 1c of the transistor 21
As a result, in Figure 8 (A>)
As shown by and ■, the collector current Ic and the oscillation output power Po are kept substantially constant against temperature changes.

FIG. 9 shows a configuration diagram of another example of a conventional oscillator.

In the figure, the same components as those in FIG. 7 are denoted by the same reference numerals, and their explanations will be omitted. In FIG. 9, the base of the NPN transistor 30 is connected to the connection point between the resistor 31 and the 24, the emitter of the transistor 30 is connected to the connection point between the other end of the resistor 31 and the power supply terminal, and the transistor 30 is connected to the connection point between the other end of the resistor 31 and the power supply terminal.
The collector of is connected to the connection point between the coil 27 and the non-ground terminal of the resistor 32.

The conventional oscillator shown in FIG. 9 has transistors 21 and 0.
The oscillation connecting section by load circuits 22 and 23 and the resistor 31.3
2. It is composed of coils 24 and 27 and a bias circuit of a transistor 21 made up of a transistor 30, and performs an oscillation operation to output a microwave oscillation signal. here,
The transistor 30 and the resistor 31 constitute a constant current circuit together with the transistor 21, and the collector current Ic of the transistor 21 is adjusted such that the voltage generated in the resistor 31 is equal to the base-emitter voltage VBE of the transistor 30.
flows.

10(A) and (B) respectively show the temperature characteristics and power supply voltage characteristics of the conventional oscillator shown in FIG. The transistor 2 is connected so that a voltage of a value equal to V' (constant) is generated across the resistor 31.
Since the collector current 1c of 1 flows, the collector current 1c is constant regardless of the fluctuation of the N source voltage -vco, as shown by Vl in FIG. 10(B). Therefore, in this conventional oscillator, the oscillation output power P○ changes due to fluctuations in the power supply voltage -vco, as shown by ■ in the figure (B).
1-meter voltage V. , will vary slightly, but since Ic remains constant, it will remain substantially constant regardless of fluctuations in the power supply voltage -vco.

[Problem to be solved by the invention]

However, in the conventional oscillator shown in FIG. 7, when the electric voltage VCC changes, the voltage generated at the thermistor 26 used as the reference voltage changes, so the
As shown, the collector current Ic of the transistor 21 changes in response to a change in the power supply voltage -Vcc. Therefore, this conventional oscillator has an oscillation output power P due to a change in the power supply voltage.
There is a problem that o changes greatly as shown by ■ in FIG. 8(B).

On the other hand, in the conventional oscillator shown in FIG. 9, the collector-emitter voltage E VBE of the transistor 30 is -211V.
/'C, so when the temperature changes, vBE' used as the M quasi-voltage changes, and therefore the first
As shown by V in FIG. 0(A), the collector current 1c of the transistor 21 changes in accordance with the temperature change. Therefore, this conventional oscillator has a problem in that the oscillation output power Po changes greatly due to temperature changes, as shown by ■ in FIG. 10<A).

The present invention has been made in view of the above points, and an object of the present invention is to provide an oscillator that can reduce fluctuations in oscillation output power with respect to both temperature changes and voltage changes.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention. In the figure, 1 is an oscillation transistor, a first load circuit 2 is connected to its emitter side, a second load circuit 3 is connected to its base side,
These constitute an oscillation circuit section. The first load circuit 2 is a load circuit that determines the oscillation conditions, and the second load circuit 3 is a load circuit that determines the oscillation frequency.

Further, a resistor circuit 4 is connected between the emitter of the transistor 1 and the power supply terminal, constitutes an emitter resistance of the transistor 1, and has temperature characteristics.

Reference numeral 5 denotes a transistor circuit, which has a reference voltage having a temperature characteristic whose temperature characteristics are canceled out by the resistor circuit 4, and the collector current of the oscillating transistor 1 is adjusted so that the voltage generated in the resistor circuit 4 is equal to the above ml voltage. A controlled current feedback is performed to the base of the oscillation transistor 1.

(Function) In the present invention, the transistor 1
A collector current of is applied. Here, the reference voltage is the voltage between the base and emitter of the transistor, and is constant regardless of changes in the power supply voltage. Therefore, even if the power supply voltage changes, the voltage generated in the resistance circuit 4 remains constant, and therefore the collector current Ic of the transistor 1 that generates the voltage in the resistance circuit 4 also remains constant.

On the other hand, the reference voltage has temperature characteristics that change due to temperature changes, but since the resistance circuit 4 has a knitting characteristic and cancels the temperature characteristics of the reference voltage of the transistor circuit 5, the reference voltage and resistance change even when there is a temperature change. There is no change relative to the voltage generated in the circuit 4, and therefore the collector current 1c of the transistor 1 also does not change.

(Example) FIG. 2 shows a configuration diagram of a first embodiment of the present invention.

In the figure, the same components as in FIG. 1 are denoted by the same reference numerals, and their explanations will be omitted. In Figure 2, load circuits 2 and 3
have the same configuration as the load circuits 22 and 23 described above, respectively. The transistor 1 is an NPN transistor which is a bipolar transistor, and the connection point between its emitter and the load circuit 2 is connected to the -2 power supply terminal via a coil 7, a thermistor 8 and a resistor 9 in series. Also,
A resistor 10 is connected in parallel to a series circuit of a CC thermistor 8 and a resistor 9, and these constitute a resistor circuit 4.

Further, the connection point between the base of the transistor 1 and the load circuit 3 is connected to the collector of an NPN transistor 12 via a coil 11. The base of the transistor 12 is connected to the coil 7, the thermistor 8, and the resistor 10, the emitter of the transistor 12 is connected to the above-mentioned VCC power supply terminal, and the collector of the transistor 12 and the coil 11 are connected to each other.
The connection point of is grounded via a resistor 13. The transistor 12 and the resistor 13 constitute the transistor circuit 5 described above.

In this example, 25°C (Tokogata) of the transistor 12
The base-emitter voltage at is vBE, and the i degree coefficient is ΔV.
B.E. The base-emitter voltage of transistor 12 at temperature T (''C) is VBE(T).Transistor 1
Let Ic be the collector current of Ic, and let R(T) be the resistance value of the resistance circuit 4 at temperature T, then VBE(T) and R(T) are respectively expressed by the following equations.

V,E(T)-VBE+ΔVB[(T-25) (
1) R (T) - Va ((T> / Ic
(21 Once the collector current 1c is determined, the resistor circuit 4
The resistance R (T) is determined. Therefore, thermistor 8. With the resistors 9 and 10, R (T) expressed by the formula (2) can be realized.

Now, the VBE of transistor 12 at room temperature is 0.6V,
ΔVBE is -ha V/'C, collector current 1c is 100m
8, the thermistor 8 is a temperature sensitive thermistor shown as a in FIG. 3, which has a resistance value of 30Ω at room temperature, and the resistors 9 and 10 are each 14Ω.

As a result, the tree mVA performs an oscillation operation based on the same operating principle as the conventional one described above, and outputs a frequency in the microwave band. Here, in this embodiment, the base-emitter voltage V8, (T) of the transistor 12 used as a reference voltage changes at a rate of -2 mV/'C due to a temperature change, but the thermistor 8. Resistance circuit 4 consisting of resistors 9 and 10
Since R(T) also changes in the same way, the collector current 1c expressed by the equation (2) remains approximately constant regardless of the temperature change, as shown by (2) in FIG. 4(A). Therefore, the oscillation output power Po also remains constant as shown by X in FIG. 4(A) regardless of temperature changes.

On the other hand, when the electric voltage fluctuates, in this embodiment, current feedback is applied to the base of the transistor 10 so that the voltage generated in the resistor circuit 4 becomes equal to E(T). Since v,E(T) is constant (however, the temperature is constant), the collector current of transistor 1 is
As shown by XI in FIG. 4(8), c remains approximately constant regardless of fluctuations in the power supply voltage. Therefore, according to this embodiment, the fourth
As shown by X in FIG. 3B, fluctuations in the oscillation output power Po due to fluctuations in the N source voltage are suppressed.

Incidentally, in the first embodiment shown in FIG. 2, an example of temperature characteristics when only the resistance value of the resistor 10 is changed from the above conditions is shown in FIG. In the same figure, X■ represents the resistance value of resistor 10 as 15Ω and 1
3Ω parallel combination or resistor fill (i.e. about 6.96Ω)
, XIV shows the temperature characteristics when the resistance value of the resistor 10 is a parallel combined resistance value of 15Ω and 15Ω (that is, 7.5Ω).

FIG. 6 shows a configuration diagram of a second embodiment of the present invention.

In the figure, the same components as in FIGS. 1 and 2 are denoted by the same reference numerals, and their explanations will be omitted. In FIG. 6, 15 is a thermistor, 16 is a resistor, and the difference from the first embodiment is that a resistance circuit 4 is constituted by a parallel circuit of these.

This embodiment is an example in which high precision is not required for the collector current Ec of the oscillation transistor 1. Therefore, the resistance circuit 4 can be configured by simply connecting one resistor 16 to the thermistor 15 in parallel. It has the advantage of being cheaper than the embodiment.

〔Effect of the invention〕

As described above, according to the present invention, the collector current of the oscillation transistor can be kept approximately constant regardless of changes in the power supply voltage, so it is possible to suppress changes in the oscillation output power due to changes in the power supply voltage, and the temperature Resistance circuits are the basis of transistor circuits even against changes! 1! Since temperature changes in voltage can be canceled out, changes in oscillation output power due to temperature changes can also be suppressed.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the oscillator of the present invention, Fig. 2 is a configuration diagram of the first embodiment of the present invention, Fig. 3 is a temperature characteristic diagram of the thermistor, and Fig. 4 is a characteristic diagram of an embodiment of the present invention. , FIG. 5 is a diagram showing an example of temperature change in the collector N current of the oscillator in FIG. 2, FIG. 6 is a configuration diagram of the second embodiment of the present invention, and FIG. 7 is a configuration diagram of an example of a conventional oscillator. , Figure 8 is a diagram showing the temperature characteristics and power supply characteristics of the oscillator shown in Figure 7, Figure 9 is a configuration diagram of another example of a conventional oscillator, and Figure 10 is a diagram showing the temperature characteristics of the oscillator shown in Figure 9. It is a figure showing special bamboo and power supply voltage characteristics. In the figure, 1 is an oscillation transistor, 2 is a first load circuit, 3 is a second load circuit, 4 is a resistance circuit, 5 is a transistor circuit, 8 and 15 are thermistors, and 12 is an NPN transistor. Principle diagram of the oscillator of the present invention Figure 1 Block diagram of the first embodiment of the present invention Figure 2 Diagram of temperature characteristics of a thermistor (C) Figure 3 Block diagram of the second embodiment of the present invention Figure: Configuration diagram of an example of a conventional oscillator Figure 7: Collector t, l! [Ic (mA) Temperature (°C) Figure 5 shows the temperature change of the collector current of the oscillator in Figure 2.
Figure 9: Another example of a conventional oscillator

Claims (1)

[Claims] A first load circuit (2) that determines oscillation conditions and oscillation frequencies on the emitter side and base side of the oscillation transistor (1), respectively.
) and a second load circuit (3), the oscillator is connected between the emitter of the oscillation transistor (1) and a power supply terminal, and has an emitter resistance of the oscillation transistor (1). A resistor circuit (4) is configured and has a temperature characteristic, and a reference voltage has a temperature characteristic whose temperature characteristic is canceled by the resistor circuit (4), and the voltage generated in the resistor circuit (4) is equal to the reference voltage. An oscillator comprising: a transistor circuit (5) that performs current feedback to the base of the oscillation transistor (1) to control the collector current of the oscillation transistor (1) so that the collector current of the oscillation transistor (1) is equal.