A Filtering ΔΣ ADC for LTE and Beyond

Abstract

This paper presents a filtering ADC for the LTE communication standard, where a second-order Delta–Sigma modulator (DSM) is incorporated into the third-order Cheby- chev channel-select filter (CSF) of the radio receiver. The CSF introduces an additional third- order suppression of both thermal and quantization DSM noise, while the CSF transfer function is maintained. A design method for the filtering ADC accounting for unavoidable DSM-DAC delays is developed and experimen- tally demonstrated. The 65 nm CMOS prototype is clocked at 576/288 MHz with an 18.5/9.0 MHz LTE bandwidth, has an in-band gain of 26 dB, an SNDR of 56.4/58.1 dB, an input-referred noise of 5 nV/ , and an out-of-band (half-dup lex) IIP3 of 20/12 dBV rms, with a power consumption of 7.9/5.4 mW and an overall state-of-the art performance.