Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Reexamination Certificate
2004-09-05
2008-09-30
Tra, Quan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
C327S553000, C327S554000, C327S555000, C327S556000, C327S557000, C327S558000, C327S559000
Reexamination Certificate
active
07429889
ABSTRACT:
Control system for programmable filters, master-slave calibration system and fully programmable high precision filter for use in such control system, such filters being provided with a filter input and a filter output including a first, first order low pass filter section comprising first and second mutually identical operational transconductance amplifiers (OTAs), having a controllable transconductance Gm from a differential voltage input having first and second differential voltage input terminals to a single current output carrying a single phase current output signals, said first and second OTAs being provided with first and second control inputs, respectively, said filter input being coupled to the first differential voltage input terminal of said first OTA. The current outputs of both first and second OTAs are being resistorless coupled to a first capacitor, the current output of the second OTA is negatively fed back to its first differential voltage input terminal to form a variable positive virtual resistance across said first capacitor, the common connection of the single current outputs of the first and second OTAs and the first capacitor constituting an output terminal of the first, first order low pass filter section, which is coupled to said filter output, the second differential voltage input terminals of the first and second OTAs being respectively coupled to first and second DC reference voltage levels, a gain and a bandwidth control signal being respectively supplied to the first and second control input terminals of said first and second OTA. To obtain an unambiguous and orthogonal control of filter parameters, such as gain, bandwidth, quality factor and/or tuning frequency, said gain control signal is provided through a first multiplier to said first control input terminal of the first, first order low pass filter section for multiplying the gain control signal with said bandwidth control signal and said bandwidth control signal at least to said second control input terminal of the first, first order low pass filter section.
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McDermott, Esq. Robert M.
Rojas Daniel
Semiconductor Ideas to Market (ITOM) B.V.
Tra Quan
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