A Tunable Current-Mode Integrator for Low-Frequency Filters
|Organization:||Boston University, 02215, US|
|I.P. Brief:||The subject technology is a differential current-mode integrator (CMI) for voltage-controllable, low-frequency, continuous-time filters. The novel design of the circuit includes the use of operational transconductance amplifiers (OTAs), transistors, inductors, and capacitors in cross-coupled identical circuits, and the connection of a DC reference voltage source to the OTA.|
|Summary of I.P.:||Through this design, the input impedance is brought to a much lower level than a standard diode-connected transistor, and lowers the input current to small voltage swings at the input nodes. This allows for the required capacitance to be much smaller than is used in standard low frequency filter designs. Characteristics from a fifth-order Butterworth low pass filter designed using the subject invention show a cutoff frequency range from 160 Hz to 5.6 kHz.
The main benefit of this design is that it allows for the use of very small capacitors and transistors, enabling all components to be placed on a single chip instead of requiring large capacitors to be placed outside the chip. Other benefits include the ability to place many of these circuits on a single VLSI chip, to tune across a wide frequency range using a single control voltage, and to be used as a building block for low pass, high pass, or band pass filters.
Commercial applications are broad and include filtering of EMI noise in wireless ports, data line transmissions, flat panel display interfaces, audio speakers, CD players, hearing aids, biomedical equipment, speech recognition systems, hearing aids, piezoelectric sensors, and seismic systems.|
|Patent:||US Utility applicaiton pending s/n 11/009,377|
|Keywords:||filters, low pass, band pass, high pass, electronics|
|Specific Market:||Semiconductors, Electronics, Speakers, Audio Equipment, Filters|
|Market Size:||Unknown, but broad applications in filtering of EMI noise in wireless ports, data line transmissions, flat panel display interfaces, audio speakers, CD players, hearing aids, biomedical equipment, speech recognition systems, hearing aids, piezoelectric s|
|State of the Art:||Precise status unknown. Certainly there are other methods for band pass filters, but none that we know off that are so compact and can be done on the same chip.|
|Figures of Merit:||Enables small packaging for low pass, band pass, and high pass filters
Tunable to a wide frequency range of 160 Hz to 5.6 KHz|
|Tech. Obstacles:||Concept proven, but additional prototype circuits should be produced for further testings.|
|Market Obstacles:||Classical filtering circuit designs are embedded in designers toolboxes and company know-how. Tight reliability performance characteristics of circuits will require additional testing.|
|Publications:||A Novel Current-Mode Integrator for Voltage-Controllable,
Low-Frequency, Continuous-Time Filters
Zibing Yang, Todd Hinck, Howard I. Cohen and Allyn E. Hubbard|
|Research Team:||Professor Allyn Hubbard, Ph.D.
Department of Electrical and Computer Engineering|