Active compensation in the switched-capacitor biquad
01 Aug 1983-Vol. 71, Iss: 8, pp 1008-1009
TL;DR: In this paper, a simple compensation scheme was proposed to reduce the sensitivity of the performance of a switched-capacitor biquad to the finite gain-bandwidth product of the op-amps.
Abstract: One of the limiting factors in the performance of high-ω p and high-Q p active filters is the finite frequency-dependent gain characteristics of operational amplifiers (op-amps). Investigated here is a simple compensation scheme to reduce the sensitivity of the performance of a switched-capacitor biquad to the finite gain-bandwidth product of the op-amps. Theoretical and experimental results show that the scheme is very useful.
Citations
More filters
Patent•
20 Oct 1999
TL;DR: In this paper, the authors proposed a method for down converting a modulated carrier signal to a demodulated baseband signal, which requires that at least some of the energy stored in the first storage device is discharged when the first switch is off.
Abstract: Methods for down converting a modulated carrier signal to a demodulated baseband signal are described herein The method requires that a first portion of energy is transferred from the modulated carrier signal, and stored at a first storage device when a first switch is on At least some of the energy stored in the first storage device is discharged when the first switch is off The method further comprises transferring a second portion of energy from the modulated carrier signal, storing at a second storage device the second portion of transferred energy when a second switch is on, and discharging at least some of the energy stored in the second storage device when the second switch is off A down-converted in-phase baseband signal portion is generated from the energy accumulated in the first storage device while both the charging and the discharging occurs, and a down-converted inverted in-phase baseband signal portion is generated from the energy accumulated in the second storage device while both the charging and the discharging occurs, and the two portions are combined with a first differential amplifier circuit to form a down-converted differential in-phase baseband signal
128 citations
Patent•
20 Apr 2001
TL;DR: In this paper, the authors described a system for down-converting and up-concussing an EM signal by recursively operating on approximate half cycles (½, 1½, 2½, etc.) of the carrier signal.
Abstract: Methods, systems, and apparatuses, and combinations and sub-combinations thereof, for down-converting and up-converting an electromagnetic (EM) signal are described herein. Briefly stated, in embodiments the invention operates by receiving an EM signal and recursively operating on approximate half cycles (½, 1½, 2½, etc.) of the carrier signal. The recursive operations can be performed at a sub-harmonic rate of the carrier signal. The invention accumulates the results of the recursive operations and uses the accumulated results to form a down-converted signal. In an embodiment, the EM signal is down-converted to an intermediate frequency (IF) signal. In another embodiment, the EM signal is down-converted to a baseband information signal. In another embodiment, the EM signal is a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal. Up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency.
106 citations
Patent•
18 Aug 1999
TL;DR: In this article, a modulating baseband signal with desired information is accepted, and a plurality of redundant spectrums is generated, each redundant spectrum comprises the necessary amplitude, phase, and frequency information to substantially reconstruct the modulating BS signal.
Abstract: The present invention includes a system and method for ensuring reception of a communications signal. A modulating baseband signal with desired information is accepted, and a plurality of redundant spectrums is generated. Each redundant spectrum comprises the necessary amplitude, phase, and frequency information to substantially reconstruct the modulating baseband signal. It is expected but not required that the redundant spectrums will be generated at a first location and sent to a second location over a communications medium. At the second location, the redundant spectrums are independently processed to recover a demodulating baseband signal for each of the redundant spectrums. In one embodiment, an error detection process is employed at the second location to detect and eliminate those demodulated baseband signals that have been corrupted during transmission. An error-free demodulated baseband signal is selected from the remaining demodulated baseband signals. The error-free demodulated baseband signal is representative of the modulating baseband signal sent over the communications medium.
103 citations
Patent•
27 Oct 2004
TL;DR: In this paper, a communication system comprising a multi-protocol, multi-bearer sub-system is described, which is a universal platform module that can transmit and receive one or more information signals in one or multiple protocols using one-or more bearer services.
Abstract: A communication system comprising a multi-protocol, multi-bearer sub-system is described herein. The sub-system is a universal platform module that can transmit and receive one or more information signals in one or more protocols using one or more bearer services. In one embodiment, the sub-system may form a portion of a transceiver that is composed of a transmitter and a receiver, and which is a gateway server between a personal area network (PAN) and the global wireless network.
101 citations
Patent•
04 Mar 2002
TL;DR: In this article, a method and system for up-converting a signal with a lower frequency to a higher frequency is described, where a switch with an oscillating signal is connected to a bias signal.
Abstract: A method and system is described wherein a signal with a lower frequency is up-converted to a higher frequency. In one embodiment, the higher frequency signal is used as a stable frequency and phase reference. In another embodiment, the invention is used as a transmitter. The up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency. When the invention is being used as a frequency or phase reference, the oscillating signal is not modulated, and controls a switch that is connected to a bias signal. When the invention is being used in the frequency modulation (FM) or phase modulation (PM) implementations, the oscillating signal is modulated by an information signal before it causes the switch to gate the bias signal. In the amplitude modulation implementation (AM), the oscillating signal is not modulated, but rather causes the switch to gate a reference signal that is substantially equal to or proportional to the information signal. In the FM and PM implementations, the signal that is output from the switch is modulated substantially the same as the modulated oscillating signal. In the AM implementation, the signal that is output from the switch has an amplitude that is a function of the information signal. In both embodiments, the output of the switch is filtered, and the desired harmonic is output.
95 citations
References
More filters
TL;DR: In this article, a pair of complementary strays-insensitive switched-capacitor (SC) integrator circuits are analyzed to determine the errors in their transfer functions due to the finite gain and finite bandwidth of the op amp.
Abstract: A pair of complementary strays-insensitive switched-capacitor (SC) integrator circuits are analyzed to determine the errors in their transfer functions due to the finite gain and finite bandwidth of the op amp. The results are used to predict the transfer function deviation of biquadratic filter sections and LC ladder simulations. It is shown that while the effect of finite op amp gain is similar to that encountered in active-RC filters, SC filters are much more tolerant of the finite op amp bandwidth. However, the relationship between transfer function error and finite op amp bandwidth is an exponential one as contrasted to the linear relationship of active-R C filters. Experimental results are presented.
192 citations
TL;DR: Discusses the effects of finite operational-amplifier gain and bandwidth on the response of the most widely used switched-capacitor filter section.
Abstract: Discusses the effects of finite operational-amplifier gain and bandwidth on the response of the most widely used switched-capacitor filter section. Formulas are derived for the minimum acceptable values of the DC amplifier gain and the unity-gain frequency under specified conditions.
111 citations
TL;DR: In this paper, the use of active compensation in precision electronic circuits employing modern IC op amps, whereby the op amps in a circuit provide "self-compensating" effects to mitigate their finite bandwidth limitations is discussed.
Abstract: The use of "active compensation" in precision electronic circuits employing modern IC op amps, whereby the op amps in a circuit provide "self-compensating" effects to mitigate their finite bandwidth limitations is discussed. In particular, several rather subtle applications in the field of RC active filters are presented. A number of novel integrator circuits having high performance are presented, and experimental results which support the theoretical derivations are given. Using these integrators considerably extends the useful frequency range of the "leap-frog" and "coupled-biquad" active filters, at no extra cost.
88 citations