Wave transmission lines and networks – Automatically controlled systems
Reexamination Certificate
2005-06-07
2008-07-15
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Automatically controlled systems
C333S202000, C327S552000
Reexamination Certificate
active
07400212
ABSTRACT:
An automatically tuned on-chip active continuous-time real bandpass filter operates on a differential signal while simultaneously being tuned using a common-mode (CM) reference signal, which results in a superior accuracy of its center frequency and bandwidth. The filter consists of two or more pairs of gm-C or other types active resonators that can be single-ended or differential. The two identical filters are tuned with CM reference that is rejected at the output of each pair of resonators. For each pair of resonators, the present frequency-tuning finds the resonant frequency, for which the bandpass (BP) and lowpass magnitude values are equal. For each pair of resonators, the present Q-tuning scheme adjusts BP magnitude at the resonant frequency and its Q to the appropriate value. The present tuning method allows building a reasonably flat passband BP filter using two or more pairs of resonators. Additionally, since both present tuning schemes rely on the amplitude detection the CM reference signal can be made small, which prevents the build-up of the intermodulation distortion in the filter.
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Glenn Kimberly E
Lee Benny
Locke Lord Bissell & Liddell LLP
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