| 摘要 |
<p>An amplifier (10) has at least several stages activated only to one of two bi-level states controlled in response to the value of an input source exceeding a threshold for each stage (40). Each stage (40) has a different threshold. The thresholds and source are arranged so that the stages change between the bi-level states as the value of the source changes relative to the thresholds of the different stages. Bi-level outputs of the stages are summed together. The values of the thresholds are continuously varied by a small amount relative to a predetermined maximum value for the source in response to a noise source that is independent of the signal source. A power supply for the stages includes an AC-DC converter having plural primary windings (48, 50) and several secondary windings (52.2 ... 52.(M-2), 52.(M)), one for each of the stages. The windings are coupled together so that at all times loading of the primary windings by the secondary windings as a result of activation of the output stages is approximately equal. The stages (40) are controlled so that the sum of the outputs of the stages remains a predetermined function despite one or a few of the stages failing. <IMAGE></p> |
