- 1、本文档共9页,可阅读全部内容。
- 2、有哪些信誉好的足球投注网站(book118)网站文档一经付费(服务费),不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
- 3、本站所有内容均由合作方或网友上传,本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺!文档内容仅供研究参考,付费前请自行鉴别。如您付费,意味着您自己接受本站规则且自行承担风险,本站不退款、不进行额外附加服务;查看《如何避免下载的几个坑》。如果您已付费下载过本站文档,您可以点击 这里二次下载。
- 4、如文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“版权申诉”(推荐),也可以打举报电话:400-050-0827(电话支持时间:9:00-18:30)。
查看更多
How RF Transformers Work
Applications for RF transformers
RF transformers are widely used in electronic circuits for :
Impedance matching to achieve maximum power transfer and to suppress undesired signal
reflection.
Voltage, current step-up or step-down.
DC isolation between circuits while affording efficient AC transmission.
Interfacing between balanced and unbalanced circuits; example: balanced amplifiers.
Transformer circuits and impedance relationships
When signal current goes through the primary winding, it generates a magnetic field which induces a
voltage across the secondary winding. Connecting a load to the secondary causes an AC current to
flow in the load.
It is generally necessary to control terminating impedances of RF signal paths, especially in wide-band
applications where path lengths are not negligible relative to wavelength. Wideband RF transformers
are wound using twisted wires which behave as transmission lines, and the required coupling occurs
along the length of these lines as well as magnetically via the core. Optimum performance is achieved
when primary and secondary windings are connected to resistive terminating impedances for which
the transformer is designed. Transformers having a turns ratio of 1:1, for example, are typically
designed for use in a 50- or 75-ohm system.
In this application note, reference is continually made to terminating impedances which the user
should provide for transformers, both for performance testing and in actual use. For the sake of
consistency in the discussion, transformers with turns ratio greater than 1:1 will be described as
step-up; that is, the secondary impedance is greater that the primary impedance. In actual use,
however, connection can be step-up or step-down as needed.
In Figure 1, three transformer winding topologies are illustrated. The one in Figure 1a is the simplest. Called an
autotransformer, this design has a tapped continuous wind
文档评论(0)