Even order fully-differential biquadratic filter application of implementation of fully-differential OTA based on commercially available IC

Author(s):  
Chaiyan Chanapromma ◽  
Amnaj Prajong ◽  
Phamorn Silapan
2015 ◽  
Vol 645-646 ◽  
pp. 980-985
Author(s):  
Dong Yan ◽  
Wen Ning Jiang ◽  
Si Qi Tao ◽  
Jian Yang ◽  
Liang Yin ◽  
...  

In this paper, the harmonic distortion of fourth-order sigma-delta modulator is analyzed. Based on the analysis non-ideal models are established and simulation results demonstrated the validity of these models. The non-linear capacitors introduce harmonic distortion and the non-linear on-resistance nearly only introduce second order harmonic distortion. The non-ideal integrators can increase the noise floor of the modulator.The fully-differential topology can be adopted to eliminate even order harmonic distortion and the operational amplifier with high performance can also be used to decrease noise floor of the modulator.


2016 ◽  
Vol 25 (09) ◽  
pp. 1650106 ◽  
Author(s):  
Chen-Nong Lee

None of the previously reported mixed-mode universal filters can achieve the following important advantage: no need of component matching conditions. This paper presents a new mixed-mode (including voltage, current, transadmittance, and transimpedance modes) universal biquadratic filter with no need of matching conditions (including no need of component matching and no need of input matching conditions). The proposed filter structure with nine outputs employs two plus-type fully differential current conveyors (P-type FDCCIIs), two grounded capacitors, four grounded resistors and one floating/grounded resistor, which can realize voltage, current, transadmittance, and transimpedance modes universal filtering responses (lowpass, highpass, bandpass, notch, and allpass) from the same topology without matching conditions. Moreover, the proposed circuit still offers many important advantages: the employment of two grounded capacitors, the simultaneous realizations of a lot of filtering functions, using only grounded resistors as the control factors of all filter parameters and gains, having controllable gains in current and transimpedance modes without disturbing filter parameters [Formula: see text], [Formula: see text]/Q, and Q, cascadably connecting the former voltage-mode (VM) stage and the latter current-mode (CM) stage, no capacitors bringing extra poles degrading high-frequency performance, and low active and passive sensitivity performances. H-spice simulations with TSMC 0.18[Formula: see text][Formula: see text]m 1[Formula: see text]P6M CMOS process technology validate theoretical predictions.


2019 ◽  
Vol 13 (3) ◽  
pp. 5334-5346
Author(s):  
M. N. Nguyen ◽  
L. Q. Nguyen ◽  
H. M. Chu ◽  
H. N. Vu

In this paper, we report on a SOI-based comb capacitive-type accelerometer that senses acceleration in two lateral directions. The structure of the accelerometer was designed using a proof mass connected by four folded-beam springs, which are compliant to inertial displacement causing by attached acceleration in the two lateral directions. At the same time, the folded-beam springs enabled to suppress cross-talk causing by mechanical coupling from parasitic vibration modes. The differential capacitor sense structure was employed to eliminate common mode effects. The design of gap between comb fingers was also analyzed to find an optimally sensing comb electrode structure. The design of the accelerometer was carried out using the finite element analysis. The fabrication of the device was based on SOI-micromachining. The characteristics of the accelerometer have been investigated by a fully differential capacitive bridge interface using a sub-fF switched-capacitor integrator circuit. The sensitivities of the accelerometer in the two lateral directions were determined to be 6 and 5.5 fF/g, respectively. The cross-axis sensitivities of the accelerometer were less than 5%, which shows that the accelerometer can be used for measuring precisely acceleration in the two lateral directions. The accelerometer operates linearly in the range of investigated acceleration from 0 to 4g. The proposed accelerometer is expected for low-g applications.


Author(s):  
Jorge Pérez Bailón ◽  
Jaime Ramírez-Angulo ◽  
Belén Calvo ◽  
Nicolás Medrano

This paper presents a Variable Gain Amplifier (VGA) designed in a 0.18 μm CMOS process to operate in an impedance sensing interface. Based on a transconductance-transimpedance (TC-TI) approach with intermediate analog-controlled current steering, it exhibits a gain ranging from 5 dB to 38 dB with a constant bandwidth around 318 kHz, a power consumption of 15.5 μW at a 1.8 V supply and an active area of 0.021 mm2.


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