| 摘要 |
<p>A front-end circuit for a radio receiver or spectrum analyser or similar device comprises an amplifier with a feedforward loop around it. An error signal, representing the distortion introduced by the main amplifier, is subtracted from the amplified signal which includes the distortion. Controllable variable phase shift and controllable variable gain elements are introduced into the circuit so that the degree of distortion cancellation can be optimised, and kept at an optimum level to minimise the amount of distortion in the output signal at all operating conditions. In embodiments of the invention, other components of the receiver front end, such as the first mixer and the first IF filter, are included in the feedforward loop.</p> |
