is an undesirable situation thousand watts. The discussion of the PA is beyond the [11]. Ideally, the conversion gain of the receiver should scope of this chapter. place non-ADC noise 10 dB above the ADC noise. Therefore, given an ADC converter noise floor, an ideal Fixed versus variable gain minimum gain can be determined that prevents the ADC In a traditional receiver, the total conversion gain is quite from dominating overall noise performance. often variable. This reduces the required dynamic range The equation for maximum conversion gain in dB is of the circuitry following the AGC, reducing the re- quired linearity requirement of those components. Also, Gmax = PADC Fullscale Pmax_signal (2.3.1) the AGC action allows for optimum signal levels over a wider range of input signal conditions. While an AGC is The equation for minimum conversion gain in dB, on still quite useful for SDR, there are certain restrictions the other hand, is on their use. Tradeoffs versus MC and SC Gmin = NSDADC + +10-10108(AXTXLH2) 10 In a single-carrier receiver there are two main issues with - NF AFE (2.3.2) setting the gain. The first issue is that it is desirable not to These equations outline the desired maximum and overdrive the front end when a strong signal of any fre- minimum conversion gain. To achieve gains beyond these quency is present. After this issue is accounted for, the bounds, an AGC can be carefully used. Even with an conversion gain can be increased or decreased as necessary AGC, the data converter will determine what the in- to achieve the sensitivity required. Although it is possible that a nearby signal will pass the front-end filters of the stantaneous dynamic range of the transceiver will be based on the difference between the noise floor and the receiver and cause a reduction of the gain and subsequent loss of the desired signal, this is typically managed through range of the converter. If Gmin is greater than G max, either the range of the ADC must be increased or the the use of "band select" or RF tracking 