High frequency power amplifying circuit and high frequency electronic component using the same
In an amplifying circuit using a grounded-emitter high frequency signal amplifying bipolar transistor, the value of impedance of a bias circuit as seen from the base terminal of the bipolar transistor is made optimum in the baseband frequency. More specifically, the resistance value of a base ballast resistor R bias connected to the base terminal of the bipolar transistor is set to a range within ±50% of [V t /I bq −(β·R e +R b )] being “ideal resistance value”, where I bq is static base current, β is the gain of the transistor, R e and R b are parasitic resistance of the emitter terminal and base terminal, respectively, and V t is voltage defined by (kT/q).
1. A high frequency power amplifying circuit for outputting an orthogonal frequency-division multiplexed signal as a radio wave, comprising:
a first bipolar transistor arranged for amplifying a high frequency signal, and having an emitter terminal connected to ground; and
a bias circuit connected to a base terminal of the first transistor, wherein impedance (R) of the bias circuit as seen from the base terminal of the first transistor satisfies the following impedance relation at baseband frequency:
1.5
·
[
Vt
lbq
-
(
β
·
Re
+
Rb
)
]
≥
R
≥
0.5
·
[
Vt
lbq
-
(
β
·
Re
+
Rb
)
]
,
where β is the gain of the first transistor,
Re is the parasitic resistance (Ω) of the emitter terminal,
Rb is the parasitic resistance (Ω) of the base terminal,
Ibq is the static current flowing into the base terminal of the first transistor when the amplitude of an input signal is zero,
k is the Bolzman constant (J/K),
q is the absolute value (C) of electronic charge,
T is the absolute temperature (K), and
Vt is the voltage defined by the following formula:
V
t
=
k
T
q
.
2. The high frequency power amplifying circuit according to claim 1 , wherein the impedance R satisfies the following impedance relation:
1.2
·
[
Vt
lbq
-
(
β
·
Re
+
Rb
)
]
≥
R
≥
0.8
·
[
Vt
lbq
-
(
β
·
Re
+
Rb
)
]
.
3. The high frequency power amplifying circuit according to claim 1 wherein:
a base ballast resistor is connected to the base terminal of the first transistor; and
an impedance (R bias ) of the base ballast resistor as seen from the base terminal of the first transistor satisfies the impedance relation when R=R bias in the impedance relation.
4. The high frequency power amplifying circuit according to claim 1 , wherein:
the bias circuit includes a first external terminal, a second external terminal, a second transistor, a third transistor, a first resistor, a second resistor, and a third resistor,
one end of the first resistor is connected to the first external terminal,
an emitter terminal of the second transistor is connected to ground,
the other end of the first resistor, a collector terminal of the second transistor, and a base terminal of the third transistor are connected at a first node,
one end of the second resistor is connected to a base terminal of the second transistor,
a collector terminal of the third transistor is connected to the second external terminal,
the other end of the second resistor, an emitter terminal of the third transistor, and one end of the third resistor are connected at a second node, and
the other end of the third resistor is connected to the base terminal of the first transistor.
5. The high frequency power amplifying circuit according to claim 4 , wherein the first external terminal and the second external terminal are connected to a control voltage power source.
6. The high frequency power amplifying circuit according to claim 4 , wherein the first external terminal is electrically connected to the second external terminal.
7. The high frequency power amplifying circuit according to claim 4 , wherein the third resistor is a base ballast resistor.
8. The high frequency power amplifying circuit according to claim 1 , wherein the slope of gain (dB) relative to input power (dBm) when the amplifier output is 18 dBm is 0.02 dB/dBm or less.
9. The high frequency power amplifying circuit according to claim 1 , wherein the deviation of gain (dB) when the input power is in a range of −10 to +5 dBm is 0.3 dB or less.
10. A high frequency electronic component using a high frequency power amplifying circuit according to claim 1 .
11. A high frequency power amplifying circuit for outputting an orthogonal frequency-division multiplexed signal as a radio wave, comprising:
a first bipolar transistor, arranged for amplifying a high frequency signal, and having an emitter connected to ground; and
a bias circuit connected to a base terminal of the first transistor, wherein an impedance (R) of the bias circuit as seen from the base terminal of the first transistor satisfies the following impedance relation at baseband frequency:
Vt
lbq
≥
R
≥
(
Vt
lbq
-
16
)
,
where Ibq is the static current flowing into the base terminal of the first transistor when the amplitude of input signal is zero,
k is the Bolzman constant (J/K),
q is the absolute value (C) of electronic charge,
T is the absolute temperature (K), and
Vt is the voltage defined by the following formula:
V
t
=
k
T
q
.
12. The high frequency power amplifying circuit according to claim 11 , wherein:
a base ballast resistor is connected to the base terminal of the first transistor; and
an impedance (R bias ) of the base ballast resistor as seen from the base terminal of the first transistor satisfies the impedance relation when R=R bias in the impedance relation.
13. The high frequency power amplifying circuit according to claim 11 , wherein:
the bias circuit includes a first external terminal, a second external terminal, a second transistor, a third transistor, a first resistor, a second resistor, and a third resistor,
one end of the first resistor is connected to the first external terminal,
an emitter terminal of the second transistor is connected to ground,
the other end of the first resistor, a collector terminal of the second transistor, and a base terminal of the third transistor are connected at a first node,
one end of the second resistor is connected to a base terminal of the second transistor,
a collector terminal of the third transistor is connected to the second external terminal,
the other end of the second resistor, an emitter terminal of the third transistor, and one end of the third resistor are connected at a second node, and
the other end of the third resistor is connected to the base terminal of the first transistor.
14. The high frequency power amplifying circuit according to claim 13 , wherein the first external terminal and the second external terminal are connected to a control voltage power source.
15. The high frequency power amplifying circuit according to claim 13 , wherein the first external terminal is electrically connected to the second external terminal.
16. The high frequency power amplifying circuit according to claim 13 , wherein the third resistor is a base ballast resistor.
17. The high frequency power amplifying circuit according to claim 11 , wherein the slope of gain (dB) relative to input power (dBm) when the amplifier output is 18 dBm is 0.02 dB/dBm or less.
18. The high frequency power amplifying circuit according to claim 11 , wherein the deviation of gain (dB) when the input power is in a range of −10 to +5 dBm is 0.3 dB or less.
19. A high frequency electronic component using a high frequency power amplifying circuit according to claim 11 .