JPH04273711A - Transistor circuit - Google Patents

Abstract

PURPOSE:To make a dynamic range into a broad band and to set depending performance on temperature and a source voltage satisfactorily by providing a base-grounded amplifier between a vector synthesis circuit and a transmission circuit in a horizontal oscillation circuit. CONSTITUTION:An input current (i) is inputted to a transistor Q5 that becomes the base-grounded amplifier biased by a bias circuit Vbias and a current source Iref. Output amplified by the transistor Q5 is supplied to a phase shifter 10 after being folded in a form of current (i) at a current mirror circuit CM. In other words, since an amplifier by the grounding of the transistor Q5 is used as a current amplifier, deterioration in frequency characteristic can be suppressed even compared with the input current (i), and also, the bias circuit Vbias and the current source Iref can be comprised in constitution effective for the improvement of dynamic ranger temperature depending performance.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transistor circuit suitable for widening the dynamic range and for performance dependent on temperature and power supply voltage.

0003

2. Description of the Related Art When it is desired to shift an arbitrary input current i by an arbitrary phase as shown in FIG. 7, or when it is desired to provide selectivity to an arbitrary frequency band, resistors R1, R
A load element such as a phase shifter or a filter composed of 2 and a capacitor C is used.

FIG. 8 shows a vector synthesis circuit 1 and a phase shift circuit of a horizontal oscillation circuit of a television receiver, in which the current source Iin of FIG. 7 is constructed with a specific circuit. The control voltage output by the horizontal frequency automatic control circuit 1 (not shown) is applied to NPN transistors Q1 and Q2.
, Q3, and Q4, and outputs the current i so that oscillation is performed at the same frequency as the received horizontal frequency. The current i is directly output to a phase shift circuit 3 composed of resistors R1, R2, and a capacitor C, and is phase-shifted by a phase amount determined by the element so as to satisfy the oscillation conditions of the entire horizontal oscillation circuit. .

In the conventional circuit, the input current i is directly input to the phase shifter 3.
Alternatively, since the current is input to a filter, there is a problem that the dynamic range of the current source Iin at the previous stage becomes narrow. To explain with reference to FIG. 8, when a current i flows into the phase shift circuit 3, a voltage of i·R1 is generated across the resistor R1. That is, the operating upper limit voltage at the output end of the vector synthesis circuit 2 is approximately Vcc-i.R1, and when it exceeds this voltage, the transistors Q2 and Q4 become saturated. Resistance R
1 is the other resistance R2 and capacitance C1 of phase shift circuit 2.
This also determines the phase shift amount of the phase shift circuit 2.
If the resistor R1 is made smaller, the value of the capacitance C1 increases significantly, so it is practically impossible to reduce the value of the resistor R1 when it is built into an IC.

Therefore, in order to widen the dynamic range in the conventional circuit, it is necessary to set the power supply voltage Vcc to a considerably large value. However, in low-voltage power supply circuits such as LCD television receivers that cannot provide a large power supply voltage Vcc, not only cannot a large dynamic range be obtained, but the horizontal oscillation circuit stops oscillating due to lack of gain. This may lead to defects in circuit operation.

Furthermore, the current source I1 must be one in which changes in the power supply voltage Vcc do not affect the input current i. At this time, changes in the maximum and minimum voltages and DC component voltage at the output end of the circuit with respect to changes in the power supply voltage Vcc are as follows if the configuration is as shown in FIG. 8 in which the input current i is directly output to the phase shift circuit 3. For example, the graph in Figure 4 (
It can be plotted as shown in a), (b), and (c). Here, since the maximum voltage (a) and the DC component voltage (b) have dependence on the power supply voltage Vcc, as Vcc increases, they shift toward a higher voltage level while maintaining the voltage difference. Generally, in a low voltage circuit where the minimum operating supply voltage is set low, the voltage difference is necessarily set small to compensate for operation at the minimum Vcc, and the power supply voltage V
In cases where cc is set high, the dynamic range is not effectively utilized. The higher the power supply voltage Vcc is, the smaller the interval in the vertical axis direction between graph (b) and graph (a) becomes, compared to the same interval between graph (b) and graph (c), and the DC level (b) becomes smaller. This means that signals that swing upward are likely to be distorted.

Furthermore, a constant current source such as a bandgap circuit is generally used as a current source that does not depend on the power supply voltage Vcc. However, when a bandgap circuit is used, the input current i changes due to temperature changes, which in turn causes the output of the phase shifter or filter to change as well. In a horizontal oscillation circuit as shown in FIG. 8, in which the current increase range is directly transmitted to the subsequent circuit, a problem may occur in which the oscillation conditions are deviated from.

[0009]

In the conventional circuit, since the input current i is directly input to the phase shifter or filter, there is a problem that the dynamic range of the current source Iin at the previous stage is narrowed. In addition, it is common to use a bandgap circuit for the current source I1, assuming that changes in the power supply voltage Vcc are not affected by the input current i, but a bandgap circuit changes the input current i due to temperature changes.
Furthermore, there is a problem in that the output of the phase shifter or filter also changes.

An object of the present invention is to provide a transistor circuit that widens the dynamic range without deteriorating the frequency characteristics of the input current i, obtains good operation even in a low voltage power supply circuit, and has good temperature dependent performance. With the goal.

[Configuration of the invention]

0012

[Means for Solving the Problems] The present invention provides a common base bias circuit that biases a current source connected to a power supply and an input signal using a bias circuit that is dependent on the power supply voltage or temperature or can be arbitrarily set. It is provided with means for inputting the amplified output into the amplifier and supplying the amplified output to the load element as a current.

[0013]

[Operation] By using the above means, the output current obtained by the base-grounded amplification means is folded back by the current mirror circuit, and this is used as the input of the additional element, thereby widening the dynamic range without deteriorating the f-characteristics. A circuit can be added to reduce the adverse effects of voltage and temperature on circuit operation.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The input current i is connected to the bias circuit Vbias and the current source Iref.
It is input to the emitter of transistor Q5, which serves as a common base amplifier biased by . transistor Q
The output amplified by 5 is outputted from the collector, turned back in the form of a current i' by a current mirror circuit CM made up of transistors Q6 and Q7, and supplied to a phase shifter 10 made up of resistors R1 and R2 and a capacitor C1. Since the amplifier with the base of the transistor Q5 being grounded is used as the current amplifier in this way, the deterioration of the frequency characteristics can be minimized compared to the input current i. In addition, the common base amplifier has a bias circuit Vbias.
, the current source Iref can be configured effectively to improve the dynamic range and temperature-dependent performance. For example, in the case of an oscillator, the bias circuit Vbias and the current source Iref can be set arbitrarily within the range provided that a current i' that satisfies the oscillation conditions can be obtained.

Bias voltage Vbias and current source current Iref when the bias circuit Vbias and current source Iref of transistor Q5 in FIG. 1 are configured as shown in FIG.
Q8 )) Iref = (Vcc-(Vbias+VB
E(Q5)))/R3.

The output terminal voltage of the vector synthesis circuit 11 is Vc
c-(i+i')·R3, and the resistance R3 can be arbitrarily determined. On the other hand, since the resistance R1 cannot take a very small value as described in FIG. 8, it is generally designed so that i.R1 >(i+i').R3. When the current source Iin is configured as shown in FIG. 8, the dynamic range of the vector synthesis circuit 2 can be widened, and FIG. 3 shows a bias circuit configured to effectively utilize the dynamic range when the power supply voltage Vcc is increased. This figure shows another embodiment of the present invention in which Vbias and current source Iref are configured. In order to effectively use the dynamic range when the power supply voltage Vcc is increased, the slope of the graph should be made gentler at the point Q when the lowest operating voltage Vomin at the circuit output end is exceeded to some extent, as shown in graph (b') in Figure 4. Just change the direction. The position of Q and the slope of the graph can be arbitrarily determined by the designer depending on the signal waveform being handled.When the signal swings with the same amplitude above and below the DC level, the graph (a) and the slope shown in Figure 4 are used. Set so that (b') corresponds to the intermediate line of (c).

In this embodiment, by controlling the bias of the common base amplifier, the input current i' to the phase shift circuit can be changed in synchronization with the power supply voltage, thereby achieving the above object.

FIG. 3 shows the current source Iref ' of FIG. 2 connected in series with a resistor R5, R6, diodes D1, D
2 are connected in parallel. In the figure, when V is less than the sum of the voltage across diodes D1 and D2 and the voltage drop across resistor R6, transistor Q8
All of the collector current flows to the resistor R5, and if V becomes a voltage higher than the sum, the collector current flows to the resistor R5 and the diode D1.
, D2, and the resistor R6. The voltage V is the voltage across the diodes D1 and D2 and the resistance R
6 Vcc value when equal to the sum of voltage drops is Vturn
Then, the relationship between Vcc and i' can be expressed by the graph in FIG. In other words, i' is made to have dependence on Vcc. i' flows to the resistor R1 of the next stage phase shift circuit 10, and a voltage of i'·R1 is generated across the resistor R1. On the other hand, when the conventional common base amplifier is not used, the voltage generated across the resistor R1 is i·R1. In other words, the input terminal voltage of the phase shift circuit is Vcc-i'・R
1, Vcc-i·R1, it can be seen that the former value takes a smaller value. Since the input current of the phase shift circuit 10 is phase-shifted and fed back to the first-stage reference oscillation circuit in the form of a voltage, if we consider this result in relation to the graph of FIG. 4, we can see that the voltage value becomes Vcc=Vturn. In,
The slope becomes gentle as shown in graph (b'). As described above, the dynamic range can be used effectively.

FIG. 6 shows another embodiment of the present invention configured to suppress the adverse effects of temperature changes on circuit operation.

In this embodiment, when current i changes due to temperature change, the change is canceled out to make current i' independent of temperature, thereby suppressing the adverse effects of temperature change on circuit operation. To be independent of temperature, resistor R3
It can be seen that the current i (R3) flowing through can be increased or decreased depending on the temperature. That is, when the input current i increases, i·R3 may be increased, and when i decreases, i·R3 may be increased.

A current source I2 dependent on thermoelectromotive force VT, such as a bandgap circuit, is connected to the input terminal of the current mirror circuit composed of PNP transistors Q5 and Q8.
, current source I1 and NPN transistor Q9,
Base-emitter voltage VB as configured by Q10
Connect an E-dependent current source. From this, the following relational expression holds true for the voltage V(R4) appearing across the resistor R4.

[0023]V(R4) =R4 ・I2 +R4
・Ic (Q9)=R4 ・VT ・1 nN/Rs
+R4 ・VBE(Q10) /R7 However, Ic
(Q9): Transistor Q9 collector current N
: Unique constant Rs of the bandgap circuit
: Current setting resistor of bandgap circuit Now, assuming that the base-emitter voltages of PNP transistors Q5 and Q8 are equal, the voltage V(R3) generated across R3 is equal to V(R4). Also, since i(R3) = V(R3)/R3, i
(R3) can be expressed by the following formula.

i(R3) =R4/R3・VT・1 n
N/Rs +R4 /R3 ・VBE(Q10) /R
7 Taking the partial differential of the above equation with respect to temperature T, we get (however, ignoring the temperature dependence of resistance) 2i(R3)
/2T=1/R3 ・R4 / R3 ・ln N・
2VT/2T+1/R7 ・R4 / R3 ・2V
BE(Q10)/2T, that is, 1/R in the above formula
By arbitrarily setting the values of s and 1/R7, the temperature dependence of the current flowing through the resistor R3 can be adjusted. For example, if the input current i is a current that has temperature dependence due to VT, set 1/Rs to a larger value than 1/R7 so that i・R3 also has temperature dependence due to VT. Bye. Similarly, if the input current i has temperature dependence due to the base-emitter voltage, or if it is due to a combination of both, it can be set arbitrarily.

According to this embodiment, it is possible to improve low voltage, reduce the adverse effects on the circuit due to changes in power supply voltage and temperature, and enable stable oscillation operation.

It should be noted that the present invention is not limited to the above-described embodiments, and the same object can be achieved even if, for example, the bias means of the common base amplifier is configured by other means.

[0027]

[Effects of the Invention] As explained above, according to the present invention,
By providing a common base amplifier between the vector synthesis circuit and the phase shift circuit in the horizontal oscillation circuit, the dynamic range can be expanded without deteriorating the frequency characteristics of the transmitted signal, and good operation can be obtained even with a low voltage power supply. ,
In addition, it is possible to reduce the adverse effects on circuit operation due to changes in power supply voltage and temperature.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram more specifically shown in FIG. 1;

FIG. 3 is a circuit diagram showing another embodiment of the invention.

FIG. 4 is a characteristic diagram for comparing the operation of the present invention and the conventional operation.

FIG. 5 is a characteristic diagram showing the operation of the present invention.

FIG. 6 is a circuit diagram showing another embodiment of the invention.

FIG. 7 is a conventional circuit diagram.

FIG. 8 is another conventional circuit diagram.

[Explanation of symbols]

Iin, Iref……Current source Q5......transistor Vbias……bias circuit CM……Current mirror circuit

Claims (4)

[Claims] [Claim 1] A first electrode whose one terminal is connected to a reference potential.
a current source having one terminal connected to the reference potential or another reference potential;
a transistor in which the other terminal of the current source is connected to the emitter; a bias circuit that is dependent on the power supply voltage or temperature or can be set arbitrarily; and a bias circuit connected to the base of the transistor, and a current source from the collector of the transistor to the load element. 1. A transistor circuit comprising: supplying means. 2. The transistor circuit according to claim 1, wherein the first current source is constituted by a resistor. 3. The bias circuit is characterized in that the voltages are synthesized in an arbitrary ratio using a bandgap voltage and a base-emitter voltage of a transistor, each of which has positive and negative temperature dependence. 1. The transistor circuit according to 1. 4. The transistor circuit according to claim 1, wherein the bias circuit is a voltage-divided power supply voltage.