Circuit requirements of a direct conversion paging receiver

Circuit requirements of a direct-conversion FLEX paging receiver with the zero-crossing interpolation demodulator are derived by means of high-level simulation. Impacts of the limitations on noise and nonlinearity characteristics of the radio frequency (RF) stage, the in-phase and quadrature-phase mismatch, and the local oscillator frequency drift are analyzed relative to the degradation of the bit error rate. Official specifications on radio paging receivers are introduced to ensure the minimum performance. It is shown that an RF front-end with 25-dB gain, 5.3-dB noise figure, and 11-dBm second order intercept point makes the receiver qualified for the sensitivity, desensitization, and intermodulation requirements.