A quadrature bandpass continuous-time delta-sigma modulator for tri-mode GSM-EDGE/UMTS/DVB-T receivers, with power scaling technique

Author(s):  
Chen-Yen Ho ◽  
Wei-Shan Chan ◽  
Yung-Yu Lin ◽  
Tsung-Hsien Lin
2017 ◽  
Vol 27 (03) ◽  
pp. 1850044 ◽  
Author(s):  
Alireza Shamsi ◽  
Esmaeil Najafi Aghdam

Power consumption and bandwidth are two of the most important parameters in design of low power wideband modulators as power consumption is growing with the increase in bandwidth. In this study, a multi bit wideband low-power continuous time feed forward quadrature delta sigma modulator (CT-FF-QDSM) is designed for WLAN receiver applications by eliminating adders from modulator structure. In this method, a real modulator is designed and its excess loop delay (ELD) is compensated, then, it is converted into a quadrature structure by applying the complex coefficient to loop filter. Complex coefficients are extracted by the aid of a genetic algorithm to further improve signal to noise ratio (SNR) for bandwidth. One of the disadvantages of CT-FF-QDSM is the adders of loop filters which are power hungry and reduce the effective loop gain. Therefore, the adders have been eliminated while the transfer function is intact in the final modulator. The system level SNR of the proposed modulator is 62.53[Formula: see text]dB using OSR of 12. The circuit is implemented in CMOSTSMC180nm technology. The circuit levels SNR and power consumption are 54[Formula: see text]dB and 13.5[Formula: see text]mW, respectively. Figure of Merit (FOM) obtained from the proposed modulator is about 0.824 (pj/conv) which is improved (by more than 40%) compared to the previous designs.


Author(s):  
Eka Fitrah Pribadi ◽  
Rajeev Kumar Pandey ◽  
Paul C.-P. Chao

Abstract A high-resolution, low offset delta-sigma analog to digital converter for detecting photoplethysmography (PPG) signal is presented in this study. The PPG signal is a bio-optical signal incorporated with heart functionality and located in the range of 0.1–10 Hz. The location to get PPG signal is on a pulsating artery. Thus the delta-sigma analog-to-digital (DS ADC) converter is designed specifically in that range. However, the DS ADC circuitry suffers from 1/f noise under 10 Hz frequency range. A chopper based operational amplifier is implemented in DS ADC to push the 1/f noise into high-frequency noise. The dc offset of the operational amplifier is also pushed to the high-frequency region. The DS ADC circuitry consists of a second-order continuous-time delta-sigma modulator. The delta-sigma modulator circuitry is designed and simulated using TSMC 180 nm technology. The continuous-time delta-sigma modulator active area layout is 746μm × 399 μm and fabricated using TSMC 180 nm technology. It operates in 100 Hz bandwidth and 4096 over-sampling ratios. The SFDR of the circuit is above 70 dB. The power consumption of the delta-sigma modulator is 35.61μW. The simulation is performed in three different kinds of corner, SS, TT, and FF corner, to guarantee the circuitry works in different conditions.


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