Highly-linear continuous-time filter for a 3-volt supply with PL

Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

327552, 327308, 327558, 327557, 327556, H04B 110

Patent

active

060972440

ABSTRACT:
A continuous-time filter is highly linear even when used with reduced 3-volt power supplies. In each stage of a multi-stage ladder network, resistor networks are attached to each input of a differential op amp. Each resistor network uses fixed resistors in series between the inputs and an intermediate node, and a fixed input resistor between the intermediate node and the op-amp input. The fixed input resistor improves linearity compared with a linear transistor. A transistor connects the internal node to ground, acting as a variable resistor to adjust the equivalent resistance of the resistor network. A control voltage applied to the gate of the transistor is generated by an analog control loop. The control voltage is the voltage input to a voltage-controlled oscillator (VCO) in a phase-locked loop (PLL). The analog PLL control loop adjusts the control voltage and the resistance continuously as the filter operates. A voltage comparator detects when the control voltage is out of a range, activating a calibration signal. Filtering stops and a digital successive-approximation register adjusts capacitances of feedback capacitors around the op amps. The capacitance in the VCO is also adjusted, changing the control voltage. Capacitance converges to the desired value by comparing the control voltage to a mid-range target voltage.

REFERENCES:
patent: 3772617 (1973-11-01), Ciesielka
patent: 4626808 (1986-12-01), Nossek
patent: 4918338 (1990-04-01), Wong
patent: 5262779 (1993-11-01), Sauer
patent: 5345119 (1994-09-01), Khoury
patent: 5492935 (1996-02-01), Okanobu
patent: 5608665 (1997-03-01), Wyszynski
patent: 5729230 (1998-03-01), Jensen et al.
Banu, M and Tsividis, Y., "An Elliptic Continuous-Time CMOS Filter with On-Chip Automatic Tuning" IEEE JSSC vol. SC-20, No. 6, pp 1114-21, Dec. 1985.
Moon and Song, "Design of a Low-Distortion 22-KHz Fifth-Order Bessel Filter" IEEE JSSC vol. 28, No. 12, pp 1254-64, Dec. 1993.
Durham and Redman-White, "Integrated Continuous-Time Balanced Filters for 16-b DSP Interfaces" IEEE JSSC vol. 28, No. 7, pp 835-39, Jul. 1993.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Highly-linear continuous-time filter for a 3-volt supply with PL does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Highly-linear continuous-time filter for a 3-volt supply with PL, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Highly-linear continuous-time filter for a 3-volt supply with PL will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-667706

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.