| 摘要 |
A radio frequency receiver includes an amplifier and a detector that produces a bias control signal indicating the level of the signal environment in which the receiver is currently operating. A bias generator sets the bias level of the amplifier according to the bias control signal, where the bias level tends to increase as the signal level increases. Other circuits within the early stages or front end of a radio frequency receiver can also have such reactively adjusted bias levels. These include buffers for local intermediate frequency oscillators and radio frequency to intermediate frequency mixers or converters. The invention can be used to increase the range of linearity (and thus the intermodulation immunity) of RF amplification stages. It can also be used to reduce typical power consumption by reducing the bias level under typical conditions and relying on the bias control to increase bias levels under adverse signal conditions. The invention can be particularly advantageous for applications where power is at a premium and the receiver, or at least its front end, must operate while the device is in standby mode. Such applications include mobile, portable and hand held pagers and wireless telephones and Internet connections. If standby mode operation in non-maximum signal environments dominates the usage of the receiver, then the invention can substantially increase battery life.
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