Optimal power and noise allocation for analog and digital sections of a low power radio receiver

Abstract

We determine the optimal allocation of power between the analog and digital sections of an RF receiver, while meeting the BER constraint. Unlike conventional RF receiver designs, we treat the SNR at the output of the analog front end (SNRAD) as a design parameter rather than a specification to arrive at this optimal allocation. We first determine the relationship of the SNRAD to the resolution and operating frequency of the digital section. We then use power models for the analog and digital sections to solve the power minimization problem. As an example, we consider a 802.15.4 compliant low-IF receiver operating at 2.4 GHz in 0.13 μm technology with 1.2 V power supply. We find that the overall receiver power is minimized by having the analog front end provide an SNR of 1.3 dB and the ADC and the digital section operate at 1-bit resolution with 18 MHz sampling frequency while achieving a power dissipation of 7 mW.