JP2002185274A - Gain switching amplifying circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gain switching amplifying circuit capable of decreasing a phase change associated with gain switching in a high-frequency amplifying circuit. SOLUTION: An amplifying circuit having phase characteristics identical to those at a high gain is provided in series in an ordinary gain switching amplifying circuit, and the output thereof is connected to the output of the gain switching amplifying circuit. Thus, phase characteristics identical to those at a high gain can be obtained at a low gain, thereby decreasing the phase change associated with the gain switching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency amplifier circuit, and more particularly, to a gain-switching amplifier circuit capable of reducing a phase change accompanying gain switching.

[0002]

2. Description of the Related Art FIG. 12 is a schematic block diagram showing a configuration of a first conventional gain switching amplifier circuit. In FIG.
Q3 is a transistor that amplifies an input signal. The voltage source E2 is a bias voltage of Q3. R1 is a resistor for preventing an input signal from flowing to the bias circuit.
R2 is a resistor inserted in the emitter circuit of Q3 and Q3
The adjustment of the emitter current flowing through is performed. C1 is a capacitor inserted in the emitter circuit of Q3, and passes a high-frequency component of the emitter current of Q3. The power supply E4 is connected to the base of the transistor Q2 and is a voltage source for controlling the emitter currents of the transistors Q1 and Q2 together with the gain setting input. The voltage value of E4 is set lower than E1 to perform the switching operation. E1 is a power supply for the entire gain switching amplifier circuit. The inductor L1 is connected to the collector of Q2, and is a load for passing only the DC signal without passing the signal amplified by Q3.

[0003] An input signal is input to the base of a transistor Q3 and amplified. The signal amplified by Q3 is switched using the transistor Q1 and the transistor Q2. Q
When the gain switching signal applied to the base of 1 is 0 volt, the signal amplified by Q3 passes through Q2 and flows to the output side. When the gain switching signal applied to the base of Q1 is at the same E1 volt as the power supply voltage, the signal amplified by Q3 passes through Q1 and does not flow to Q2. For this reason, when the gain switching signal is set to E1 volt, no signal appears on the output side, and the gain switching operation is performed.

The gain switching operation will be further described with reference to FIG. Where Ic1 is the collector current of Q1,
Vb1 is the base voltage of Q1, Ic2 is the collector current of Q2,
Vb2 is the base voltage of Q2. Vc3 is the collector voltage of Q3, and Ic3 is the collector current of Q3.

At this time, the following relationship is established from the well-known Ebers-Mor relational expression. Vbe1 = Vb1−Vc3 Vbe2 = Vb2−Vc3 Vbe1 = Vt · ln (Ic1 / Is1) Vbe2 = Vt · In (Ic2 / Is2) Vt = k · T / q Ic3 = Ic1 + Ic2 where k is the Boltzmann constant and T is absolute Temperature, q, is the electronic charge.

At this time, the following relationship is established. Ic1 = Ic3 / (1 + exp (−Vid / Vt)) Ic2 = Ic3 / (1 + exp (Vid / Vt)) Vid = Vbe1−Vbe2 Therefore, when Vid >> Vt, Ic1ＩIc3Ic2 ≒ 0. If Vid << Vt, then Ic1c0 Ic2 ≒ Ic3.

As described above, the current Ic3 can be switched according to the value of the gain setting input Vb1.

FIG. 14 is a small signal equivalent circuit of a transistor. Where b is a base terminal, c is a collector terminal, e
Represents an emitter terminal. rπ is the base resistance, C
π is the base capacitance, gm is the transconductance, and ro is
Output resistance. At this time, the following relationship is established. rπ = Vt / Ib Cπ = τF · Ic / Vt gm = Ic / Vtro = Va / Ic where Vt = kT / q = 26 [mV] (T = 300 ° K) k: Boltzmann constant = 1.38 * 10 ^ -23 [JK-1] T: absolute temperature [° K] q: electron charge = 1.60 * 10 ^ -19 [C] τF: forward base transit time Va: early voltage.

FIG. 13 is a circuit diagram showing the conventional first gain switching amplifier circuit shown in FIG. 12 as a small signal equivalent circuit. The conventional gain switching operation will be described with reference to FIG.

In FIG. 13, the relationship between the input v and ic3 is first determined. The circuit equation of Q3 is as follows: v1_3 = v-ie3.Ze3 ie3 = v1_3 / Zb + gm3.v1_3 Ze = R2 + 1 / (j.omega.C1) Zb = r.pi.3 + 1 / (j.omega.C.pi.3) By solving this circuit equation, ic3 = gm3 {1- (1 / Zb + gm3) / (1 / Zb + gm3 + 1 / Ze)}. V = gm3 {1- (Ze / Zb + gm3.Ze) / (Ze / Zb + gm3 · Ze + 1)} · v | Ze | <| Zb |, so that Ze / Zb can be omitted, and ic3 ≒ gm3 {1- (gm3 · Ze) / (gm3 · Ze + 1)} · v ≒ gm3 {1-1 / (1 + 1 / (gm3.Ze))}. v | 1 / gm3 · Ze | >> 1, so that ic3 ≒ gm3 · v. Here, gm3 = Ic3 / Vt. As described above, ic3 is proportional to the input v and has substantially the same phase.

Next, the relationship between ic3 and ic2 is determined. The DC collector current of Q2 is Ic2, and the small signal collector current of Q2 is i
The small signal base currents of c2 and Q2 are ib2, the DC collector current of Q1 is Ic1, the small signal collector current of Q1 is ic1, Q1
Is the small-signal base current, and the impedance of the load L1 is ZL. The potentials of the emitter of Q1, the emitter of Q2, and the collector of Q3 are the same, which is vc. The output voltage is set to vout. Furthermore, the base is Q
2. Both Q1 are grounded, and v1_1 = v1_2 = -vc. At this time, the relationship between the terminal currents of Q2 and Q1 and ic3 is as follows: ie1 = ib1 + ic1 ie2 = ib2 + ic2 ic3 = ie1 + ie2. | Ib1 | << | ic1 |, | ib2 | << | ic2 |
Therefore, if ib1 and ib2 are omitted, ie1 ≒ ic1 ie2 ≒ ic2 ic3 = ie1 + ie2 ≒ ic1 + ic2.

Incidentally, ic2 and ic1 are expressed by the following equations (1) and (2): ic1 = −vc · gm1−vc / ro1 (1) ic2 = −vc · gm2 + ( vout-vc) / ro2 (2)

At high gain, Ic2 >> Ic1. g
Since m = Ic / Vt, gm2 >> gm1. Since ro = Va / Ic, ro2 << ro1. Thus | ic2 | >>>> ic1 |. Therefore i
c3 becomes ic3 ≒ ic2 and has the same phase.

At a low gain, Ic2 << Ic1. At this time, since gm = Ic / Vt, gm2 << gm1. Also, since ro = Va / Ic, ro2 >> ro1. Thus | ic2 | << | ic1 |. Therefore i
c3 is ic3 ≒ ic1. From the above equation (1), as in the following equation (3), vc = − {(ro1) / (1 + gm1 · ro1)} · ic3 (3)

From the above equation (2), the following equation (4) holds: ic2 = − {(1 + gm2 · ro2) / (ro2 + ZL)} · vc (4) By substituting the above equation (3) into this, ic2 = {(1 + gm2 · ro2) / (ro2 + ZL)} · {(ro1) / (1
+ gm1 · ro1)} · ic3.

Using the relationships of gm = Ic / Vt and ro = Va / Ic, ic2 = {(1 + Va / Vt) / (ro2 + ZL)}. {(Ro1) / (1 + Va)
/ Vt)｝ · ic3. Therefore, ic2 = {(ro1) / (ro2 + ZL)} · ic3. As described above, the phase of ic2 is rotated as compared with the phase of ic3.

Using the relation ro = Va / Ic, ic2 = {(Va / Ic1) / (Va / Ic2 + ZL)}. Ic3. Since Ic1 >> Ic2 at the time of low gain, 0 ≒ | ic2 | << | ic3 | (5) as shown in the following equation (5), indicating that the gain is reduced.

As described above, in the first conventional gain switching amplifier circuit, the phase changes with the gain switching.

FIG. 15 is a circuit diagram showing a configuration of a second conventional gain switching amplifier circuit. The difference between the second conventional example and the first conventional example is that the resistor R1 and the capacitor C1 in the emitter circuit of Q3 in the first conventional example do not exist in the second conventional example.

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first conventional example, since the impedance of the emitter is 0, v1_3 = v, so the same relationship as in the first embodiment is obtained. ic3 = gm3 · v. Since the relationship between ic3 and output current ic2 is the same as in the first conventional example, the phase changes with the gain switching.

[0021]

As described above, in the conventional configuration, the current flowing through the transistor changes in order to perform the gain switching operation, and the output resistance ro of the gain switching transistor changes. And the phase of the output signal changes.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a high-frequency amplifier circuit in which a change in phase due to a gain switching operation is reduced.

[0023]

In order to achieve the above object, the present invention provides, in addition to a conventional circuit, a second capacitor having one connected to an input and the other connected to the base of a fifth transistor. Is connected to the second capacitor and the base of the fifth transistor, and the other is connected to the third power supply. The third resistor is connected to one of the third resistors and the other is grounded.
A fifth transistor having a base connected to the second capacitor and the third resistor, an emitter connected to the fourth resistor and the third capacitor, and a collector connected to the emitter of the fourth transistor; Is connected to the emitter of the fifth transistor and the third capacitor and the other is grounded, and the third is connected to the emitter of the fifth transistor and the fourth resistor and the other is grounded. A configuration including a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output, or A configuration in which a fifth resistor connected to the first power supply and the other is connected to the output is added, or a fifth resistor connected to the first power supply and the other connected to the output is added to the configuration. A configuration in which one is connected to the first power supply and the other is connected to the output without the first inductor, or in addition to the second conventional circuit, one is connected to the input and the other is connected to the base of the fifth transistor. A connected second capacitor, one connected to the second capacitor and the base of the fifth transistor and the other connected to the third power supply, a third resistor connected to the third power supply, and one connected to the third resistor. A fifth power supply having a ground connected to a third power supply, a base connected to the second capacitor and the third resistor, an emitter connected to the fourth resistor and the third capacitor, and a collector connected to the emitter of the fourth transistor.
Transistor, one of which is connected to the emitter of the fifth transistor and the third capacitor and the other is grounded, and the other is connected to the emitter and the fourth resistor of the fifth transistor and the other is grounded. A configuration comprising a third capacitor, a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output;
Alternatively, a fifth resistor in which one is connected to a first power supply and the other is connected to an output is added to the above-described configuration, or a fifth connection in which one is connected to a first power supply and the other is connected to an output to the configuration 5, the first inductor connected to the first power supply and the other connected to the output is removed, or the second conventional circuit is added, and one is connected to the input and the other is connected to the first power supply. A second capacitor connected to the base of the fifth transistor, one connected to the second capacitor and the base of the fifth transistor, the other connected to the third power supply, and one connected to the third power supply. A third power supply connected to a resistor and the other grounded, a fifth transistor having a base connected to the second capacitor and the third resistor, an emitter grounded and a collector connected to the emitter of the fourth transistor, The fourth
And a fourth transistor connected to the base of the second transistor, the emitter connected to the collector of the fifth transistor, and the collector connected to the output, or one of the above-described structures is connected to the first power supply. A fifth resistor connected to the output and the other connected to the output, or a fifth resistor connected to the first power supply and the other connected to the output, and one connected to the first power supply. And the first inductor connected to the output and the other connected to the output is removed.

According to the present invention, a change in phase due to a gain switching operation can be reduced by the above-described configurations.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a figure showing an embodiment. FIG. 2 is a diagram showing an equivalent circuit of the first embodiment shown in FIG. Now, the DC collector current of Q3 is Ic3, the small signal collector current of Q3 is ic3,
The small signal base current of Q3 is ib3, the DC collector current of Q2 is Ic2, the small signal collector current of Q2 is ic2, the small signal base current of Q2 is ib2, and the DC collector current of Q1 is Ic.
1. The small signal collector current of Q1 is ic1, the small signal base current of Q1 is ib1, and the impedance of load L1 is ZL. The potentials of the emitter of Q1, the emitter of Q2, and the collector of Q3 are the same, which is referred to as vc. The output voltage is set to vout. Hereinafter, the operation of the first embodiment will be described with reference to FIG.

First, the relationship between the input v, ic3 and ic5 is determined. The circuit equation of Q3 is as follows: v1_3 = v-ie3.Ze3 ie3 = v1_3 / Zb + gm3.v1_3 Ze3 = 1 / (1 / R2 + j.omega.C1) Zb = 1 / (1 / r.pi.3 + j.omega.C.pi.3) By solving this circuit equation, ic3 = gm3 {1- (1 / Zb + gm3) / (1 / Zb + gm3 + 1 / Ze3)}. V = gm3 {1- (Ze3 / Zb + gm3.Ze3) / (Ze3 / Zb + gm3 · Ze3 + 1)} · v | Ze3 | <| Zb |, so that Ze3 / Zb can be omitted, and ic3 ≒ gm3 {1- (gm3 · Ze3) / (gm3 · Ze3 + 1)} · v ≒ gm3 {1-1 / (1 + 1 / (gm3.Ze3))}. v | 1 / gm3 · Ze3 | >> 1, so that ic3 ≒ gm3 · v. Similarly, ic5 ≒ gm5 · v. Here, gm3 = Ic3 / Vt, gm5 = Ic5 / Vt
It is. As described above, ic3 and ic5 are proportional to the input v,
The phases are almost the same.

Next, the relationship between ic3 and ic2 is determined. The base is grounded for both Q2 and Q1, and v1_1 = v1_2 = −vc. At this time, the relationship between the terminal currents of Q2 and Q1 and ic3 is as follows: ie1 = ib1 + ic1 ie2 = ib2 + ic2 ic3 = ie1 + ie2. Since ib1 << ic1 and ib2 << ic2, omitting ib1 and ib2 results in ie1 ≒ ic1 ie2 ≒ ic2 ic3 = ie1 + ie2 ≒ ic1 + ic2. ic2 and ic1 are represented by the following equations (6) and (7): ic1 = −vc · gm1−vc / ro1 (6) ic2 = −vc · gm2 + (vout−vc) / ro2 (7)

At high gain, Ic2 >> Ic1. g
Since m = Ic / Vt, gm2 >> gm1. Since ro = Va / Ic, ro2 << ro1. Thus | ic2 | >>>> ic1 |. Therefore i
c3 is ic3 ≒ ic2.

At low gain, Ic2 << Ic1. At this time, since gm = Ic / Vt, gm2 << gm1. Also, since ro = Va / Ic, ro2 >> ro1. Thus | ic2 | << | ic1 |. Therefore i
c3 is ic3 ≒ ic1. From the above equation (6), as in the following equation (8), vc = − {(ro1) / (1 + gm1 · ro1)} · ic3 (8) From the above equation (7), As shown in Expression (9), ic2 = − {(1 + gm2 · ro2) / (ro2 + ZL)｝ · vc (9) Substituting this into the above equation (8), ic2 = {(1 + gm2 · ro2) / (ro2 + ZL)} · {(ro1) / (1
+ gm1 · ro1)} · i3. Using the relationships of gm = Ic / Vt and ro = Va / Ic, ic2 = {(1 + Va / Vt) / (ro2 + ZL)}. {(ro1) / (1 + Va
/ Vt)} · ic3. Therefore, ic2 = {(ro1) / (ro2 + ZL)} · ic3. As described above, the phase of ic2 is rotated as compared with the phase of ic3.

Further, using the relationship of ro = Va / Ic, ic2 = {(Va / Ic1) / (Va / Ic2 + ZL)｝ · ic3. Since Ic1 >> Ic2 at the time of low gain, the following equation (10) holds: 0 ≒ | ic2 | << | ic3 | (10)

As described above, the relationship between ic3 and ic2 is the same as that of the conventional example. When the gain is high, ic3 ≒ ic2, and when the gain is low, ic2 = {(ro1) / (ro2 + ZL)｝ · ic3. As described above, the phase of ic2 rotates as compared with ic3 at the time of low gain.

Further, since | ib4 | << | ic4 |,
ic4 ≒ ic5. Therefore, the output current iout is iout = ic2 + ic5. At this time, Q is set so that | ic2 | << | ic5 |
When a gain of 5 is set, iout ≒ ic5. Since ic5 has the same phase as v, the output phase does not change even when the gain is low.

As described above, according to the gain switching amplifier circuit of the first embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 4 shows a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that Q in the first embodiment is different from that of the first embodiment.
3, the resistor R2 and the capacitor C1 in the emitter circuit are
This is absent in the second embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first embodiment, the same relationship as in the first embodiment is obtained because the impedance of the emitter is 0, ic3 = gm3 · v. Therefore, in the second embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the second embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 5 shows a third embodiment of the present invention. The difference between the third embodiment and the first embodiment is that Q in the first embodiment is different from that of the first embodiment.
3 and a resistor R2 and a capacitor C1 in the emitter circuit of Q5.
3 does not exist in the third embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is determined in the same manner as in the first embodiment, the same relationship as in the first embodiment ic3 = gm3 · v is obtained because the impedance of the emitter is 0. For this reason, in the third embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the third embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 6 shows a fourth embodiment of the present invention. The difference between the fourth embodiment and the first embodiment is that a resistor R5 exists in parallel with the inductor L1 in the first embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first embodiment, the same relationship as in the first embodiment is obtained as ic3 = gm3 · v since the impedance of the emitter is 0. Therefore, in the fourth embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the fourth embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 7 shows a fifth embodiment of the present invention. The difference between the fifth embodiment and the fourth embodiment is that Q in the fourth embodiment is different from that of the fourth embodiment.
The resistor R2 and the capacitor C1 in the emitter circuit of No. 3 are
This does not exist in the fifth embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first embodiment, the same relationship ic3 = gm3 · v as in the first embodiment is obtained because the impedance of the emitter is 0. Therefore, in the fifth embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the fifth embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 8 shows a sixth embodiment of the present invention. The difference between the sixth embodiment and the fourth embodiment is that Q in the fourth embodiment is different from that of the fourth embodiment.
3 and a resistor R2 and a capacitor C1 in the emitter circuit of Q5.
No. 3 does not exist in the sixth embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first embodiment, the same relationship as in the first embodiment is obtained because the impedance of the emitter is 0: ic3 = gm3 · v. Therefore, in the sixth embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the sixth embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Seventh Embodiment) Next, a seventh embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 9 shows a seventh embodiment of the present invention. The difference between the seventh embodiment and the first embodiment is that the inductor L1 in the first embodiment does not exist, and a resistor R5 exists instead of the position where the inductor L1 existed. .

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first embodiment, the same relationship as in the first embodiment becomes ic3 = gm3 · v because the impedance of the emitter is 0. Therefore, in the seventh embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit of the seventh embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Eighth Embodiment) Next, an eighth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 10 shows an eighth embodiment of the present invention. The difference between the eighth embodiment and the seventh embodiment is that the resistor R2 and the capacitor C1 in the emitter circuit of Q3 in the seventh embodiment are different.
However, this does not exist in the eighth embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is determined in the same manner as in the first embodiment, the same relationship as in the first embodiment is obtained because the emitter impedance is 0: ic3 = gm3 · v. For this reason, in the eighth embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the eighth embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

(Ninth Embodiment) Next, a ninth embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 11 shows a ninth embodiment of the present invention. The difference between the ninth embodiment and the seventh embodiment is that the resistor R2 and the capacitor C1 in the emitter circuit of Q3 in the fourth embodiment are different.
Further, the resistor R4 and the capacitor C3 in the emitter circuit of Q5 do not exist in the ninth embodiment.

When the relationship between the input v and the emitter current ie3 of Q3 is obtained in the same manner as in the first embodiment, the impedance ic3 of the emitter is 0, so that the same relationship as in the first embodiment, ic3 = gm3 · v. Therefore, in the ninth embodiment, as in the first embodiment, the output phase does not change even when the gain is low.

As described above, by using the gain switching amplifier circuit according to the ninth embodiment of the present invention, it is possible to keep the phase of the output signal unchanged even when the gain is switched.

[0059]

As is clear from the description of the embodiments described above, according to the present invention, when the gain is switched,
It is possible to provide a gain switching amplifier circuit in which a change in phase is reduced in a high frequency amplifier circuit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a gain switching amplifier circuit according to a first embodiment;

FIG. 2 is a circuit diagram showing the circuit shown in FIG. 1 as a small-signal equivalent circuit;

FIG. 3 is a diagram showing a gain switching operation;

FIG. 4 is a diagram showing a configuration of a gain switching amplifier circuit according to a second embodiment;

FIG. 5 is a diagram showing a configuration of a gain switching amplifier circuit according to a third embodiment;

FIG. 6 is a diagram showing a configuration of a gain switching amplifier circuit according to a fourth embodiment;

FIG. 7 is a diagram illustrating a configuration of a gain switching amplifier circuit according to a fifth embodiment;

FIG. 8 is a diagram showing a configuration of a gain switching amplifier circuit according to a sixth embodiment;

FIG. 9 is a diagram showing a configuration of a gain switching amplifier circuit according to a seventh embodiment;

FIG. 10 is a diagram showing a configuration of a gain switching amplifier circuit according to an eighth embodiment;

FIG. 11 is a diagram showing a configuration of a gain switching amplifier circuit according to a ninth embodiment;

FIG. 12 is a diagram showing a configuration of a conventional first gain switching amplifier circuit;

FIG. 13 is a circuit diagram showing a conventional first gain switching amplifier circuit as a small signal equivalent circuit;

FIG. 14 is a small signal equivalent circuit of a transistor,

FIG. 15 is a diagram showing a configuration of a second conventional gain switching amplifier circuit.

[Explanation of symbols]

 R1 resistor R2 resistor R3 resistor R4 resistor R5 resistor C1 capacitor C2 capacitor C3 capacitor Q1 transistor Q2 transistor Q3 transistor Q4 transistor Q5 transistor E1 power supply E2 bias power supply E3 bias power supply E4 bias power supply L1 load inductor

Claims (10)

[Claims] 1. A base connected to an input and an emitter connected to a second
A third transistor having a collector connected to the emitters of the first and second transistors and having a collector connected to the first capacitor and a first resistor having one connected to the input and the other connected to the second power supply. A second power supply having one connected to the first resistor and the other grounded, one connected to the emitter of the third transistor and the other grounded, and one connected to the emitter of the third transistor. A first capacitor connected to the other and grounded, a first transistor having a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply; A second transistor having an emitter connected to the collector of the third transistor and a collector connected to the output, and one connected to the collector of the first transistor and the first inductor. A first power supply having the other grounded, a first inductor having one connected to the first power supply and the other connected to the output, and a fourth power supply having one connected to the base of the second transistor and the other grounded And a second capacitor having one connected to the input and the other connected to the base of the fifth transistor, and one connected to the base of the second capacitor and the fifth transistor. A third resistor having the other connected to the third power source, a third power source having one connected to the third resistor and the other grounded, a base connected to the second capacitor and the third resistor, and an emitter connected to the third capacitor. Fourth resistor and third
And a fifth transistor having a collector connected to the emitter of the fourth transistor and one connected to the fifth transistor.
A fourth resistor connected to the emitter of the third transistor and the third capacitor and the other grounded, and a third connected to the emitter and the fourth resistor of the fifth transistor and the other grounded.
And a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. Switching amplifier circuit. 2. A third transistor having a base connected to the input, an emitter grounded, and a collector connected to the emitters of the first and second transistors, one connected to the input and the other connected to the second power supply. A first resistor, a second power supply having one connected to the first resistor and the other grounded, a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply A second transistor having a base connected to the fourth power supply, an emitter connected to the collector of the third transistor, and a collector connected to the output, one of which is connected to the collector of the first transistor; A first power supply connected to the first inductor and the other grounded; a first inductor connected to the first power supply and the other connected to the output; and one connected to the base of the second transistor. A fourth power supply connected to the other and grounded,
A second capacitor having one connected to the input and the other connected to the base of the fifth transistor, one connected to the second capacitor and the base of the fifth transistor, and the other connected to the base of the fifth transistor. A third resistor connected to a third power supply, a third power supply connected to the third resistor on one side and a ground on the other side, a base connected to the second capacitor and the third resistor, and an emitter connected to the fourth resistor; Resistance and third
And a fifth transistor having a collector connected to the emitter of the fourth transistor and one connected to the fifth transistor.
A fourth resistor connected to the emitter of the third transistor and the third capacitor and the other grounded, and a third connected to the emitter and the fourth resistor of the fifth transistor and the other grounded.
And a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. Switching amplifier circuit. 3. A third transistor having a base connected to the input, an emitter grounded, and a collector connected to the emitters of the first and second transistors, one connected to the input and the other connected to the second power supply. A first resistor, a second power supply having one connected to the first resistor and the other grounded, a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply A second transistor having a base connected to the fourth power supply, an emitter connected to the collector of the third transistor, and a collector connected to the output, one of which is connected to the collector of the first transistor; A first power supply connected to the first inductor and the other grounded; a first inductor connected to the first power supply and the other connected to the output; and one connected to the base of the second transistor. A fourth power supply connected to the other and grounded,
A second capacitor having one connected to the input and the other connected to the base of the fifth transistor, one connected to the second capacitor and the base of the fifth transistor, and the other connected to the base of the fifth transistor. A third resistor connected to the third power source, a third power source connected to one of the third resistors and the other grounded, a base connected to the second capacitor and the third resistor, and an emitter grounded. A fifth transistor having a collector connected to the emitter of the fourth transistor, a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. A gain switching amplifier circuit comprising a fourth transistor. 4. A base connected to the input and an emitter connected to the second
A third transistor having a collector connected to the emitters of the first and second transistors and having a collector connected to the first capacitor and a first resistor having one connected to the input and the other connected to the second power supply. A second power supply having one connected to the first resistor and the other grounded, one connected to the emitter of the third transistor and the other grounded, and one connected to the emitter of the third transistor. A first capacitor connected to the other and grounded, a first transistor having a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply; A second transistor having an emitter connected to the collector of the third transistor and a collector connected to the output, and one connected to the collector of the first transistor and the first inductor. A first power supply having the other grounded, a first inductor having one connected to the first power supply and the other connected to the output, and a fifth resistor having one connected to the first power supply and the other connected to the output And a fourth power supply, one of which is connected to the base of the second transistor and the other is grounded, wherein the fourth is connected to the input and the other is connected to the base of the fifth transistor. A third capacitor having one connected to the second capacitor and the base of the fifth transistor and the other connected to the third power supply, and a third connected to one connected to the third resistor and the other grounded. 3, a base connected to the second capacitor and the third resistor, and an emitter connected to the fourth resistor and the third resistor.
And a fifth transistor having a collector connected to the emitter of the fourth transistor and one connected to the fifth transistor.
A fourth resistor connected to the emitter of the third transistor and the third capacitor and the other grounded, and a third connected to the emitter and the fourth resistor of the fifth transistor and the other grounded.
And a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. Switching amplifier circuit. 5. A third transistor having a base connected to the input, an emitter grounded, and a collector connected to the emitters of the first and second transistors, one connected to the input and the other connected to the second power supply. A first resistor, a second power supply having one connected to the first resistor and the other grounded, a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply A second transistor having a base connected to the fourth power supply, an emitter connected to the collector of the third transistor, and a collector connected to the output, one of which is connected to the collector of the first transistor; A first power supply connected to the first inductor and the other grounded, a first inductor connected to the first power supply and the other connected to the output, one connected to the first power supply and the other output To A connected fifth resistor and one connected to the second
A fourth power supply connected to the base of the third transistor and the other grounded, a second capacitor having one connected to the input and the other connected to the base of the fifth transistor, A third resistor connected to the second capacitor and the base of the fifth transistor and the other connected to the third power supply, a third power supply connected to one of the third resistors and the other grounded, Is connected to the second capacitor and the third resistor, and the emitter is connected to the fourth resistor and the third resistor.
And a fifth transistor having a collector connected to the emitter of the fourth transistor and one connected to the fifth transistor.
A fourth resistor connected to the emitter of the third transistor and the third capacitor and the other grounded, and a third connected to the emitter and the fourth resistor of the fifth transistor and the other grounded.
And a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. Switching amplifier circuit. 6. A third transistor having a base connected to the input, an emitter grounded, and a collector connected to the emitters of the first and second transistors, one connected to the input and the other connected to the second power supply. A first resistor, a second power supply having one connected to the first resistor and the other grounded, a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply A second transistor having a base connected to the fourth power supply, an emitter connected to the collector of the third transistor, and a collector connected to the output, one of which is connected to the collector of the first transistor; A first power supply connected to the first inductor and the other grounded, a first inductor connected to the first power supply and the other connected to the output, one connected to the first power supply and the other output To A connected fifth resistor and one connected to the second
A fourth power supply connected to the base of the third transistor and the other grounded, a second capacitor having one connected to the input and the other connected to the base of the fifth transistor, A third resistor connected to the second capacitor and the base of the fifth transistor and the other connected to the third power supply, a third power supply connected to one of the third resistors and the other grounded, Is connected to the second capacitor and the third resistor, the emitter is grounded, the collector is connected to the emitter of the fourth transistor, and the base is connected to the fourth power supply and the base of the second transistor. A gain switching amplifier circuit comprising: a fourth transistor having an emitter connected to a collector of a fifth transistor and a collector connected to an output. 7. A base connected to the input and an emitter connected to the second
A third transistor having a collector connected to the emitters of the first and second transistors and having a collector connected to the first capacitor and a first resistor having one connected to the input and the other connected to the second power supply. A second power supply having one connected to the first resistor and the other grounded, one connected to the emitter of the third transistor and the other grounded, and one connected to the emitter of the third transistor. A first capacitor connected to the other and grounded, a first transistor having a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply; A second transistor having an emitter connected to the collector of the third transistor and a collector connected to the output, and one connected to the collector of the first transistor and the fifth resistor and the other A first power supply grounded, one first
A fifth resistor connected to the power supply and the other connected to the output, and a fourth power supply connected to the base of the second transistor and connected to the base of the second transistor and grounded at the other, A second capacitor having one connected to the input and the other connected to the base of the fifth transistor, and a third capacitor having one connected to the base of the second capacitor and the fifth transistor and the other connected to the third power supply. , A third power supply having one connected to the third resistor and the other grounded, a base connected to the second capacitor and the third resistor, and an emitter connected to the fourth resistor and the third resistor.
And a fifth transistor having a collector connected to the emitter of the fourth transistor and one connected to the fifth transistor.
A fourth resistor connected to the emitter of the third transistor and the third capacitor and the other grounded, and a third connected to the emitter and the fourth resistor of the fifth transistor and the other grounded.
And a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. Switching amplifier circuit. 8. A third transistor having a base connected to the input, an emitter grounded, and a collector connected to the emitters of the first and second transistors, one connected to the input and the other connected to the second power supply. A first resistor, a second power supply having one connected to the first resistor and the other grounded, a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply A second transistor having a base connected to the fourth power supply, an emitter connected to the collector of the third transistor, and a collector connected to the output, one of which is connected to the collector of the first transistor; A first power supply connected to a fifth resistor and the other grounded, a fifth resistor connected to the first power supply and the other connected to the output, and one connected to the base of the second transistor and the other Connect A gain switching amplifier circuit including a grounded fourth power supply, a second capacitor having one connected to the input and the other connected to the base of the fifth transistor, and one connected to the second capacitor and the fifth capacitor. A third resistor connected to the base of the transistor and the other connected to the third power supply, a third power supply connected to one of the transistors to the third resistor and the other grounded, and a base connected to the second capacitor and the third power supply; Connect the emitter to the fourth resistor and the third
And a fifth transistor having a collector connected to the emitter of the fourth transistor and one connected to the fifth transistor.
A fourth resistor connected to the emitter of the third transistor and the third capacitor and the other grounded, and a third connected to the emitter and the fourth resistor of the fifth transistor and the other grounded.
And a fourth transistor having a base connected to the fourth power supply and the base of the second transistor, an emitter connected to the collector of the fifth transistor, and a collector connected to the output. Switching amplifier circuit. 9. A third transistor having a base connected to the input, an emitter grounded, and a collector connected to the emitters of the first and second transistors, one connected to the input and the other connected to the second power supply. A first resistor, a second power supply having one connected to the first resistor and the other grounded, a base connected to the gain setting input, an emitter connected to the collector of the third transistor, and a collector connected to the first power supply A second transistor having a base connected to the fourth power supply, an emitter connected to the collector of the third transistor, and a collector connected to the output, one of which is connected to the collector of the first transistor; A first power supply connected to a fifth resistor and the other grounded, a fifth resistor connected to the first power supply and the other connected to the output, and one connected to the base of the second transistor and the other Connect A gain switching amplifier circuit including a grounded fourth power supply, a second capacitor having one connected to the input and the other connected to the base of the fifth transistor, and one connected to the second capacitor and the fifth capacitor. A third resistor connected to the base of the transistor and the other connected to a third power supply, a third power supply connected to one of the third resistors and the other grounded, and a base connected to the second capacitor and the third power supply; A fifth transistor connected to a resistor, having an emitter grounded and a collector connected to the emitter of the fourth transistor, a base connected to the fourth power supply and the base of the second transistor, and an emitter connected to the collector of the fifth transistor; A gain switching amplifier circuit comprising: a fourth transistor connected to the output and a collector connected to the output. 10. A communication terminal having a high-frequency amplifier circuit in a wireless transmission / reception unit, comprising the gain switching amplifier circuit according to any one of claims 1 to 9.