| 摘要 |
State of the art: Summing amplifiers with feedback operational amplifiers are generally known. …<??>Technical problem: The weighting factors are quotients obtained from the feedback resistance common to all addends and the individual series resistances. Only the feedback resistance has a directly proportional effect. The individual series resistances have an inversely proportional effect. The formation of pre-defined complex weighting factors is impeded. The problem occurs, for example, in two-wire/four-wire interfaces. …<??>Fundamental principle: Two-stage summing amplifier, where the second stage (VS2') adds up using real factors and complex factors are implemented in the first stage (VS1'). …<??>Advantages: Interfaces which are balanced and unbalanced about earth are equally simple to implement with one capacitor only. In-phase signals can be evaluated (SSE) with ease; in-phase signalling (DS) is possible. …<IMAGE>… |
