A 5-10GHz low power bang-bang all digital PLL based on programmable digital loop filter

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.

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DESIGNING LOW POWER OF SIGMA DELTA MODULATOR FOR BIOMEDICAL APPLICATION

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237205000287 ◽

2005 ◽

Vol 17 (04) ◽

pp. 181-185 ◽

Cited By ~ 9

Author(s):

HO-YIN LEE ◽

CHEN-MING HSU ◽

SHENG-CHIA HUANG ◽

YI-WEI SHIH ◽

CHING-HSING LUO

Keyword(s):

Power Consumption ◽

Low Power ◽

Biomedical Application ◽

Loop Filter ◽

Biomedical Signal ◽

Sigma Delta Modulator ◽

Sigma Delta ◽

Pass Filter ◽

Low Pass Filter ◽

Power Application

This paper discusses the design of micro power Sigma-delta modulator with oversampling technology. This Sigma-delta modulator design is paid special attention to its low power application of portable electronic system in digitizing biomedical signals such as Electro-cardiogram (ECG), Electroencephalogram (EEG) etc. [1]. A high performance, low power second order Sigma-delta modulator is more useful in analog signal acquisition system. Using Sigma-delta modulator can reduce the power consumption and cost in the whole system. The original biomedical signal can be reconstructed by simply applying the digital bit stream from the modulator output through a low-pass filter. The loop filter of this modulator has been implemented by using switch capacitor (SC) integrators and using simple circuitry consists of OpAmps, Comparator and DAC. In general, the resolution of modulator is about 10 bits for biomedical application. In this two order Sigma-delta modulator simulation results of the 1.8V sigma delta modulator show a 68 dB signal-to-noise-and-distortion ratio (SNDR) in 4 kHz biomedical signal bandwidth and a sampling frequency equal to 1 MHz in the 0.18 μ m CMOS technology. The power consumption is 400 μ W. It is very suitable for low power application of biomedical instrument design.

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