A kind of line transformer and radio-frequency power amplifier
Technical field
The invention belongs to technical field of communication equipment, and in particular to a kind of line transformer and use line transformer
Radio-frequency power amplifier.
Background technique
Communication is one of activity necessary to human survival, and telecommunication relies on the transmission of electromagnetic signal, and transmitter is electricity
The necessaries that magnetic signal transmits at a distance.Radio-frequency power amplifier is the critical component of transmitter, impedance-matching transformer
It is the critical component of radio-frequency power amplifier.
In radio-frequency power amplifier, requires impedance-matching transformer and impedance matching is made to power amplifier tube and load.
For spread bandwidth and Insertion Loss is reduced, impedance-matching transformer generallys use line transformer.On textbook and in the past
In practice, the impedance transformation ratio of line transformer is all 1:n2, for example, 1:4,1:9,1:16,1:25 ... ....However, practical
In, these impedance ratios fixed usually are unable to meet demand.For example, the radio-frequency power amplifier of 125W, supply voltage are
When 24~28V, using the transformer of 1:4, linear index (intermodulation) is unqualified;Using the transformer of 1:9, efficiency index does not conform to again
Lattice.
Summary of the invention
To solve the above problems, the present invention overcomes prior art prejudice, the impedance transformation ratio (letter of line transformer is broken through
Impedance ratio) it is referred to as integer, i.e. 1:n2(n=1,2,3,4 ... ...), conventional design, propose that a kind of impedance transformation ratio is non-integer
Line transformer and using this line transformer radio-frequency power amplifier, to meet unconventional impedance transformation ratio
Matching demand.Further, the invention also discloses the matching transformers of impedance ratio 1:6.25 a kind of, to solve background technique
The radio-frequency power amplifier of middle 125W cannot meet linear index and efficiency index when supply voltage is 24~28V simultaneously
Practical problem.
Technical solution of the present invention includes:
Scheme one: a kind of line transformer, the circle number of primary coil are N1, and the circle number of secondary coil is N2, N1 ≠ N2;
N=N1/N2, n=1/N;The voltage change ratio of the line transformer is 1:n, impedance transformation ratio 1:n2。
As a kind of priority scheme, the N=2/5, the n=2.5, the voltage change ratio are 1:2.5, and the impedance becomes
It changes than for 1:6.25.
Scheme two: a kind of radio-frequency power amplifier, using line transformer described in scheme one.
Scheme three: a kind of line transformer, including magnetic core and two coaxial cables, the coaxial cable are around in magnetic side by side
Core two encloses;Constitute primary coil after the outer conductor of two coaxial cables is in parallel, the inner conductors of two coaxial cables relative to leading outside
Body respectively extends half-turn, and constitutes secondary coil after head and the tail series connection;Its voltage change ratio is 1:2.5, impedance transformation ratio 1:6.25.
Scheme four: a kind of radio-frequency power amplifier, using line transformer described in scheme four, and the connection biography
The power tube of defeated line transformer primary coil and the load for connecting the line transformer secondary coil.
The utility model has the advantages that
The present invention overcomes prior art prejudice through actual verification, expands the impedance transformation ratio of line transformer from integer
Non-integer is arrived greatly, and it is limited to compensate for conventional transmission line transformer impedance transformation ratio, is unable to the skill of flexible adaptation practical application scene
Art defect, so that the application range of line transformer is broader, effect is also more preferable.
The matching transformer of impedance ratio 1:6.25 disclosed by the invention can be applied to the radio-frequency power amplifier of 125W, supply
When piezoelectric voltage is 24~28V, linear index (intermodulation) can be met simultaneously and efficiency index is qualified.
Detailed description of the invention
Fig. 1 is the transformer circuit figure of common impedance ratio 1:4;
Fig. 2 is the transformer circuit figure of common impedance ratio 1:9;
Fig. 3 is the transformer circuit figure of the impedance ratio 1:6.25 in embodiment 1.
Specific embodiment
The matching transformer T2 in matching transformer T1 and Fig. 2 in radio-frequency power amplifier shown in FIG. 1 be all according to
The impedance-matching transformer T (abbreviation matching transformer) of conventional thinking design.Radio-frequency power amplifier mainly includes being sequentially connected
Power tube, matching transformer and load.Matching transformer T specifically uses line transformer.The primary of line transformer
Coil connects the output end of power tube, secondary coil connection load.Specifically, line transformer includes magnetic core and is wound on magnetic core
On coaxial cable, the shielded layer (outer conductor) of coaxial cable primary (primary coil) the connection power tube in parallel as transformer
Output end, coaxial cable core wire (inner conductor) head and the tail be connected in series load (secondary coil), naturally it is also possible to according to specific
Demand designs in turn, i.e., using outer conductor as secondary wire coil, inner conductor is as primary coil.The no-load voltage ratio of matching transformer T is
Voltage ratio is equal to the ratio between primary coil circle number and secondary coil circle number.
In the prior art, the internal and external conductor equal length of coaxial cable, i.e. primary coil as the circle number of secondary coil,
Thus obtained impedance ratio is very limited, for example, 1:4,1:9,1:16,1:25.The present invention overcomes prior art prejudice, transmission
The internal and external conductor length of coaxial cable in line transformer is different, i.e. the circle number of primary coil and secondary coil is different, for example,
By two coaxial cables and come on magnetic core around Liang Quan, the shielded layer (outer conductor) of cable is in parallel as the primary of transformer,
The core wire (inner conductor) of cable is connected and core wire is extended half-turn as the secondary of transformer at beginning and end, obtains no-load voltage ratio
For 2:5=1:2.5, impedance ratio 1:2.52The impedance-matching transformer of=1:6.25 further can be by the impedance matching transformation
Device is applied in radio-frequency power amplifier.
As shown in Figure 1, the primary coil of matching transformer T1 is 2 circles, secondary coil is 4 circles, i.e., by two coaxial cables
And come around Liang Quan on magnetic core, using the parallel connection of the shielded layer (outer conductor) of cable as the primary of transformer, the core wire cable is (interior
Conductor) secondary of the series connection as transformer, the no-load voltage ratio N=2:4=1:2 of T1, impedance ratio=1:n2=1:22=1:4, n=1/N.
Similarly, as shown in Fig. 2, the primary coil of matching transformer T2 is 2 circles, secondary coil is 6 circles, the no-load voltage ratio N of matching transformer T2
=2:6=1:3, impedance ratio=1:n2=1:32=1:9.
The impedance ratio of matching transformer T3 in Fig. 3 is 1:6.25.Go deep into according to line transformer working principle
Understand, T3 breach line transformer no-load voltage ratio N should be integer concept circle, when coiling transformer, in matching transformation
On the basis of device T1, the length of core wire is respectively increased half-turn at the beginning and terminal of the coaxial cable of secondary coil, i.e., it is primary
Coil is 2 circles, and secondary coil is 5 circles, makes the no-load voltage ratio N=2:5=1:2.5 of transformer, impedance ratio=1:n2=1:2.52=1:
6.25.Impedance transformation ratio after matching is verified between 1:4 and 1:9, which meets radio-frequency power amplification simultaneously
The debugging of device linear index (intermodulation) and efficiency index, it is poor this addresses the problem impedance matching linear index (intermodulation) is made with T1,
Make the contradiction of impedance matching efficiency index difference with T2.
Certainly, the length of core wire can also respectively be increased into a circle at coaxial cable beginning or terminal in above-described embodiment, together
Sample is able to satisfy the debugging of radio-frequency power amplifier linear index (intermodulation) and efficiency index, but considers the symmetrical of coil both ends
Property, preferably above-mentioned symmetric scheme.
It is further to note that is provided in embodiment is the radio-frequency power amplifier for solving 125W, in supply voltage
When for 24~28V, while meeting the problem of linear index (intermodulation) and efficiency index qualification, mentality of designing of the invention can also fit
For need to specifically be debugged according to concrete application in other practical applications.
Although embodiment of the present invention is described in conjunction with attached drawing above, the invention is not limited to above-mentioned
Specific embodiments and applications field, above-mentioned specific embodiment are only schematical, directiveness, rather than restricted
's.Those skilled in the art under the enlightenment of this specification, in the range for not departing from the claims in the present invention and being protected
In the case where, a variety of forms can also be made, these belong to the column of protection of the invention.