scholarly journals A Single-Ended and Fully-Differential Universal Current-Mode Frequency Filter with MO-CF and DACA Elements

2016 ◽  
Vol 16 (3) ◽  
pp. 43-48
Author(s):  
L. LANGHAMMER ◽  
J. JERABEK ◽  
J. POLAK ◽  
D. PANEK
Author(s):  
Yong-An Li

Background: The original filter including grounded or virtual ground capacitors can be synthesized by using the NAM expansion. However, so far the filters including floating capacitor, such as Sallen-Key filter, have not been synthesized by means of the NAM expansion. This is a problem to be researched further. Methods: By using the adjoint network theory, the Sallen-Key filter including floating capacitor first is turned into a current-mode one, which includes a grounded capacitor and a virtual ground capacitor. Then the node admittance matrix, after derived, is extended by using NAM expansion. Results: At last, one VDTA Sallen-Key filter is received. It employs single compact VDTA and two grounded capacitors. Conclusion: A Butterworth VDTA second-order frequency filter based on Sallen-Key topology with fo = 100kHz, HLP = -HBP=1, is designed.


2019 ◽  
Vol 70 (4) ◽  
pp. 323-328
Author(s):  
Dan-Dan Zheng ◽  
Yu-Bin Li ◽  
Chang-Qi Wang ◽  
Kai Huang ◽  
Xiao-Peng Yu

Abstract In this paper, an area and power efficient current mode frequency synthesizer for system-on-chip (SoC) is proposed. A current-mode transformer loop filter suitable for low supply voltage is implemented to remove the need of a large capacitor in the loop filter, and a current controlled oscillator with additional voltage based frequency tuning mechanism is designed with an active inductor. The proposed design is further integrated with a fully programmable frequency divider to maintain a good balance among output frequency operating range, power consumption as well as silicon area. A test chip is implemented in a standard 0.13 µm CMOS technology, measurement result demonstrates that the proposed design has a working range from 916 MHz to 1.1 l GHz and occupies a silicon area of 0.25 mm2 while consuming 8.4 mW from a 1.2 V supply.


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