Signal-to-Noise Ratio of Direct Sampling Receivers with Realistic Sampling Circuit Models

Employing direct sampling receivers for multi-mode multi-band operation in mobile communications is advantageous due to their high flexibility and programmability. But this type of receiver needs to be properly adjusted regarding the parameters of the sampling and the quantization stage of the analog- to-digital converter to comply with certain performance requirements. This paper studies the impact of the ideal, the track-and-hold and the sample-and-hold sampling circuit on the effective in-band signal-to-noise ratio of the receive signal. It also proposes sets of valid parameters of the complete analog-to- digital converter in terms of the duty cycle, the sampling rate, and the quantization resolution for a given band-pass input signal to limit the maximum performance loss. Moreover, the investigations for the different samplers and the overall analog-to- digital converter are used to trade-off the individual parameters in case of an exemplary LTE signal reception.