ge also range is available in the receiver (determined largely by takes advantage of filtering that is distributed throughout the ADC), reduction in gain from a strong signal may the chain to eliminate undesired images as well as other cause weaker signals to be lost in the noise floor of the undesired signals that may have survived the mix down receiver. In applications such as this, a digital control loop process. The filtering should also be appropriate for the for the gain is ideal. The control loop can be used as application. A traditional single-carrier receiver would normal as long as no signals are at risk to being lost. generally apply channel filtering through the mixer stages However, if a weak signal is detected in the presence of to help control the IP3 requirements of each stage. a very strong signal, the decision could be made to allow Analog channel filtering is not possible in the case of a limited amount of clipping rather than reduce the gain a multi-carrier receiver where the channel bandwidths and risk total loss of the weak signal. Conditional situa- are not known in advance. Therefore, the mixing process tions like this are much easier to control with a digital must preserve the entire spectrum of interest. Likewise, control loop than with an analog loop, allowing much our single-carrier SDR application must also preserve the greater control of total conversion gain of the receiver. maximum possible spectrum in case the SDR re- The ADC is used to convert the IF signal or signals quirements need the full spectrum. In this case, it is into digital format for processing. Quite often the ADC probable that our single-carrier example may be is the bottleneck, and selection of the ADC is often processing many carriers, even if only one is of interest. a driving factor that determines the architecture of the As with the LNA, it would be desirable for the mixer in SDR [1, 9, 10]. Oftentimes, the designer is forced to an SDR to have an adjustable bias. As with the LNA, this select the best available 