An optimization method of a harmonic control-based distributed power amplifier, wherein the harmonic control-based distributed power amplifier, comprises:
- an input artificial uniform transmission line (1), an output artificial non-uniform transmission line (2), and plural gain units (3), wherein two ports of the output artificial non-uniform transmission line (2) are respectively connected with reactive terminals (4), and in each gain unit (3), a gate electrode of a transistor is connected with an RC parallel resonant circuit, wherein the optimization method is carried out in the following steps:
- at step 1, dividing a working frequency band into Δf1, Δf2 and Δf3, setting a fundamental frequency to f1, and obtaining an optimal fundamental wave load impedance Z10 by load pull, using Z10 as a second or third-order fixed harmonic load impedance of a frequency point within the Δf2 frequency band, wherein a class-J mode second-order harmonic load impedance of f1 is calculated in the following formula (1.1):
- Z
- 1
-
- 2
- =
- 0
- .
- 5
-
- (
- V
- D
-
- D
- -
- V
- K
- )
-
- α
-
- j
- 2
-
- I
- max
- 3
-
- π
- =
- 0
- -
- j
-
- α
-
- 3
-
- π
- 8
-
- R
- opt
- B
- (
- 0.1
- )
- wherein VDD is a voltage of a power supply, VK is a knee voltage of a transistor, Imax is a maximal drain current of a transistor −1≤α≤1 is a constant parameter, RoptB=2 (VDD−VK)/Imax is an optimal fundamental wave load impedance of a class-B power amplifier (PA);
- at step 2, setting the fundamental wave to f2, and fixing Z10 as a second-order harmonic load impedance, namely, Z22=Z10, and obtaining an optimal fundamental wave load impedance Z20 by load pull, wherein Z20 is affected by the second-order harmonic load impedance Z22:
- at step 3, setting the fundamental frequency to f3, fixing Z10 as a third-order harmonic load impedance, namely, Z33=Z10, fixing Z20 as a second-order harmonic load impedance, namely, Z32=Z20, and obtaining an optimal fundamental wave load impedance Z30 by load pull, wherein Z30 is affected by the second-order harmonic load impedance Z32 and the third-order harmonic load impedance Z33;
- at step 4, by substituting the optimal fundamental wave impedance into the following formula, calculating an initial value of a drain line impedance:
- G
- C
-
- D
-
- (
- 1
- )
- =
- G
- O
-
- P
-
- T
-
- (
- 1
- )
- (
- 0.2
- )
- G
- C
-
- D
-
- (
- i
- ≧
- 2
- )
- =
- (
- G
- OPT
-
- (
- 1
- )
- 2
- G
- DL
- +
- G
- OPT
-
- (
- 1
- )
- +
- ∑
- k
- =
- 2
- i
- G
- OPT
-
- (
- k
- )
- )
- (
- 0.3
- )
- wherein GCD(1) is an optimal characteristic conductance of a first-segment drain line, GOPT(1) is an optimal fundamental wave conductance of a first-level transistor, GCD(n) is an optimal characteristic conductance of an n-th-segment drain line, GDL is a drain terminating resistance, GOPT(n)=1/ROPT(n)=re(Zopt(n)) is an optimal fundamental wave conductance of an n-th-level transistor, and GOPT(k) is an optimal fundamental wave conductance of a k-th-level transistor;
- determining an initial value of a gate line impedance in the following formula:
- G
- CG
-
- (
- i
- )
- =
- ∑
- k
- =
- i
- n
- G
- IN
-
- (
- k
- )
- (
- 0.4
- )
- wherein GCG(i) is an optimal characteristic conductance of an i-th-segment gate line, and GIN(k) is an input conductance of the k-th-level transistor;
- further, an electrical length of the gate line and an electrical length of the drain line satisfy the following relationship, wherein θCG(i) is an electrical length of an i-th-segment gate line and θCD(i) is an electrical length of an i-th-segment drain line:
- θ
- CG
-
- (
- i
- )
- =
- θ
- CD
-
- (
- i
- )
- (
- 0.5
- )
- at step 5, terminating the second-order harmonic impedance of the Δf1 frequency band to a pure reactance part to realize a class-J working mode, and adjusting the electrical lengths of the gate line and the drain line, and when the condition of θCG(i)=θCD(i) is satisfied, introducing reactance to offset an imaginary component of the optimal fundamental wave impedance so as to complete optimization on the harmonic control-based distributed power amplifier.