JP2552027Y2 - Wideband power combining circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a wideband power combiner that combines high-frequency power from a plurality of amplifiers and high-frequency sources by a wideband transformer using a ferrite core.

(Conventional technology) Conventionally, in a circuit of this type having an input / output impedance of 50Ω, a plurality of input powers are current-combined in a tournament manner using a wide-band in-phase current-combining transformer. Finally, the voltage is raised to 50Ω using an impedance conversion transformer.

FIG. 2 shows an example of a conventional power combiner for four inputs. T1, T2, and T3 are transformers for in-phase current synthesis, and T4 is a step-up transformer for impedance conversion. R
1, R2, R3 are resistors for absorbing unbalanced components, 1,2,3,4 are 50
Ω input terminals and 5 are 50Ω output terminals. In FIG. 2, the output terminal impedance of T1 and T2 is 25Ω, and the output terminal impedance of T3 is 12.5Ω. To maintain the impedance wide band of this circuit, the characteristic impedance of the windings of T1 and T2 is 50Ω and T3 And the characteristic impedance of the winding of T4 needs to be 25Ω.

(Problems to be solved by the present invention) The T1, T2, and T3 transformers are current combining transformers that combine the currents flowing through the windings. However, the T4 transformer is a step-up transformer for impedance conversion and transmits power by the magnetic flux of the ferrite core, so there is heat generation due to core loss. Coaxial cables are often used for the windings of each transformer,
T3 and T4 are special as coaxial cables due to the characteristic impedance of 25Ω, and both T3 and T4 require windings with large power capacity to handle the final combined power. Since the transformer of T4 handles the final synthesized power, a large transformer using a large core is required, and it is difficult to obtain good impedance characteristics due to the large size.

(Means for Solving the Problems) In order to solve these drawbacks, the present invention uses a common-mode current synthesizing transformer that generates less heat in the final stage of the power synthesizing circuit, and includes a step-up transformer for impedance conversion in the preceding stage. The present invention realizes a wide-band power combiner with good wide-band impedance characteristics and small size and low heat generation.

(Embodiment) FIG. 1 shows an embodiment of the present invention, which is the same four-input wideband power combiner as FIG. T1 and T2 are input stage common-mode current combining transformers, T5 and T6 are impedance conversion step-up transformers, T7 is the final stage common-mode current combining transformer, and R1, R2, and R3 are unbalanced absorption resistors. 1,2,
3, 4 are 50Ω input terminals and 5 is a 50Ω output terminal. Describing the operation, the currents input from the input terminals 1, 2, 3, 4 are combined by T1, T2. The output terminal impedance of T1 and T2 is 25Ω, and the impedance is converted to 100Ω at T5 and T6. The output currents of T5 and T6 are finally combined by T7 and supplied to the output terminal 5. The characteristic impedance of the transformer winding to maintain the wideband of avoidance is T
The common coaxial cable can be used because both 1, T2, T5, and T6 are 50Ω, and the current flowing through each winding of T1, T2, T5, and T6 is the same. Can be used. T5 and T6 are impedance conversion transformers,
While T4 in Fig. 2 must handle the final combined power, T5 and T6 in Fig. 1 use only half of the final combined power, making it possible to reduce the size and use a 50Ω coaxial cable for the winding. As a result, good impedance characteristics can be obtained.
T7 handles the final synthesized power, but is small because of the current synthesis transformer that generates less heat, and the characteristic impedance of the winding is 10
Since it is 0Ω, there is an advantage that it can be easily formed by parallel two-wire winding.

It should be noted that even when combining a plurality of inputs other than the four inputs, the combination can be performed in the same manner as the four inputs by considering the characteristic impedance of each winding.

(Effects of the Invention) As described above, according to the present invention, a small transformer using a ferrite core with a low cost and a general winding material and a small power capacity generates little heat and has good impedance characteristics. There is an advantage that a wide band characteristic can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a four-input wideband power combiner according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a four-input wideband power combiner according to a conventional embodiment. 1,2,3,4 ... input terminal, 5 ... output terminal, T1, T2, T3 ...
Current synthesis transformer, T4 ... The last stage impedance conversion transformer, T5, T6 ... The previous stage impedance conversion transformer, T7 ... The last stage current synthesis transformer.

Claims (1)

(57) [Scope of request for utility model registration] In a broadband power combining circuit for inputting and combining a plurality of high-frequency powers in a tournament manner using a wideband common-mode current combining transformer using a ferrite core, a final output stage is provided by the common-mode current combining transformer and a preceding stage is provided by a preceding stage. A wide-band power combining circuit comprising a step-up transformer for impedance conversion.