Showing papers on "Switched capacitor published in 1980"
TL;DR: In this paper, a switched-capacitor filter is presented based on a pair of complementary integrators and has transfer functions independent of parasitic capacitances between any node and ground, and design equations are given for low-pass, bandpass, high-pass and notch biquads, as well as ladder simulation filters.
Abstract: New topologies for switched-capacitor filters are presented. The circuits are based on a pair of complementary integrators and have transfer functions independent of parasitic capacitances between any node and ground. Design equations are given for low-pass, bandpass, high-pass, and notch biquads, as well as ladder simulation filters. The ladder simulation filters are scaled for optimum dynamic range. Discrete prototypes of both cascade and ladder simulation filters are used to verify the theory.
188 citations
TL;DR: In this article, a new CMOS PCM channel filter is described, which includes transmit and receive filters on a single die, and the chip displays an idle-channel noise of typically 0 dBrnC0, a power supply rejection ratio of 40-50 dB at 1 kHz, and a fully operational power dissipation of only 35 mW.
Abstract: A new CMOS PCM channel filter is described, which includes transmit and receive filters on a single die. This chip displays an idle-channel noise of typically 0 dBrnC0, a power supply rejection ratio of 40-50 dB at 1 kHz, and a fully operational power dissipation of only 35 mW, making it very cost effective in telecommunication switching systems. The design of this chip, including architectural, switched capacitor filter, and amplifier considerations is described, and typical experimental results are presented.
130 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 theoretical considerations as well as practical circuits which are useful to the designer attempting to implement high-speed filters are presented, and the theoretical and practical circuits are discussed.
Abstract: Monolithic filters using switched-capacitor techniques are beginning to be used in commercial audio frequency communication circuits [1], [2], [10]. The fact that these filters are MOS compatible, high precision and low power makes them very attractive in these filter applications. The usefulness of switched-capacitor filters will be greatly increased if the frequency range of these filters can be extended above the voice band. The purpose of this paper is to present the theoretical considerations as well as practical circuits which are useful to the designer attempting to implement high-speed filters.
103 citations
TL;DR: In this paper, the bilinear z-transform is used for the design of switched-capacitor bandpass filters using coupled-biquad structures and employing biquad circuits which are completely insensitive to stray capacitances between any node and ground.
Abstract: A method is presented for the design of switched-capacitor bandpass filters using the bilinear z -transform. The filters are realized in low-sensitivity coupled-biquad structures and employ biquad circuits which are completely insensitive to stray capacitances between any node and ground. Geometrically symmetric (both all-pole and finite-transmissionzeros) as well as general-parameter filters are treated.
100 citations
Patent•
28 May 1980TL;DR: In this article, a switched capacitor filter has at its input, a signal converter for creating so-called 100% sample and hold signals, consisting of a plurality of switched capacitors.
Abstract: A switched capacitor filter having at its input, a signal converter for creating so-called 100% sample and hold signals. The signal converter comprises a plurality of switched capacitors. The switched capacitors, connected in parallel with each other, receive the same successive input signals and supply the so-called 100% sample and hold input signals to the switched-capacitor filter. The switched capacitors, on one hand, charge each of said input signals sequentially and, on the other hand, alternately discharge the respective stored input signals one by one.
65 citations
TL;DR: A general and efficient CAD method for simulation of switched capacitor filters and A/D and D/A converters, based on the direct implementation of controlled switch branches into the widely used modified nodal analysis technique and therefore in contrast to other methods, directly compatible with existing CAD techniques.
Abstract: A general and efficient CAD method for simulation of switched capacitor filters and A/D and D/A converters, is demonstrated. It is based on the direct implementation of controlled switch branches into the widely used modified nodal analysis technique and is therefore in contrast to other methods, directly compatible with existing CAD techniques. It allows for DC, time domain, and frequency response calculations for arbitrary clock cycles and all types of inputs (piecewise constant, sample and hold, and continuous). The circuit can also contain resistors and allows for nonlinear time domain analysis too. As implemented in the Diana program it allows for full top-down design from principle to transistor level, including clock drivers, control logic, etc. Input is directly from the circuit diagram. The method is illustrated by practical design examples.
64 citations
TL;DR: In this article, the authors describe a number of simple (first-, second-, or third-order) switched-capacitor circuits, which can be used as simple self-contained filters, or as filter sections in the cascade realization of a higher order transfer function.
Abstract: This paper describes a number of simple (first-, second-, or third-order) switched-capacitor circuits. These can be used as simple self-contained filters, or as filter sections in the cascade realization of a higher order transfer function. All these sections are free from parasitic effects, and all can be designed directly in the sampled-signal domain. Low-pass, high-pass, bandpass, and all-pass circuits are discussed, with and without finite nonzero transmission zeros.
58 citations
01 Dec 1980
TL;DR: In this paper, a technique is introduced which allows several integrator capacitors to be multiplexed onto a single operational amplifier, which can be shared by several switched capacitor filter channels, drastically reducing the number of op amps required for filter banks.
Abstract: A technique is introduced which allows several integrator capacitors to be multiplexed onto a single operational amplifier. As a result, the op amp can be shared by several switched capacitor filter channels, drastically reducing the number of op amps required for filter banks. Twenty second-order filters have been implemented in a circuit using only two op amps and 2.5 mm/SUP 2/. The design of this system is presented and its performance is discussed. Some loss of signal energy is shown to occur during the multiplexing operations, which reduces filter Q. Causes of this charge loss are described, and its effects on performance are modeled. The design of the op amp used is presented, which incorporates a new system of input stage biasing and differential to single-ended conversion, as well as other features.
51 citations
01 Mar 1980
TL;DR: The frequency axes of the two filters are mapped into each other by the bilinear s{\leftrightarrow}z transformation; this results in advantageous sensitivity and selectivity properties for the resulting switched-capacitor circuit.
Abstract: The low sensitivity of a doubly loaded reactance ladder to element-value variations is preserved in a switched-capacitor filter with the same graph if a one-to-one replacement of branch impedances is used to derive the switched filter from the reactance ladder. This paper describes the design principles and some novel circuits based on this approach. The frequency axes of the two filters are mapped into each other by the bilinear s{\leftrightarrow}z transformation; this results in advantageous sensitivity and selectivity properties for the resulting switched-capacitor circuit. In addition, the number of active components is equal to the number of inductors replaced, and is hence small. This results in very economical realization for the integrated filter.
48 citations
TL;DR: In this paper, an integrated third-order low-pass filter is proposed, which can be built by means of capacitances, ordinary switches, and voltage inverter switches, the latter being quite simply realizable by electronic means.
Abstract: Low-sensitivity switched-capacitor filters imitating LC and LC /unit-element structures can be built by means of capacitances, ordinary switches, and voltage inverter switches, the latter being quite simply realizable by electronic means (either with or even without operational amplifier). There are no restrictions on the operating rate (other than those resulting from the Nyquist theorem) nor on the location of the attenuation poles. Experimental results of an integrated third-order lowpass filter are in good agreement with theory. The effects of parasitic capacitances can be overcome by using proper design techniques.
TL;DR: In this article, switched-capacitor decimation and interpolation circuits are described, where the decimator can function as an input stage, the interpolator as an output stage in a filter system.
Abstract: Novel switched-capacitor decimation and interpolation circuits are described. The decimator can function as an input stage, the interpolator as an output stage in a filter system. This allows the use of differing clock rates in the various stages of the system, which in turn can result in simpler antialiasing requirements, more practical element values and lower sensitivities for the individual filters in the system.
TL;DR: The paper describes several new building blocks which can realize the general second-order sampled-data transfer function and can be used to realize more complex functions either by cascading them or combining them in a multiple-feedback structure.
Abstract: The paper describes several new building blocks which can realize the general second-order sampled-data transfer function. These can be used to realize more complex functions either by cascading them or combining them in a multiple-feedback structure.
Patent•
29 May 1980
TL;DR: An interpolation or smoothing filter circuit for a switched-capacitor system which transforms the sampled-and-held output signals from a switched capacacitor filter into sampled and-held signals with a doubled sample rate was proposed in this paper.
Abstract: An interpolation or smoothing filter circuit for a switched-capacitor system which transforms the sampled-and-held output signals from a switched-capacitor filter into sampled-and-held signals with a doubled sample rate. The circuit comprises an operational amplifier whose noninverting input lead is connected to a switched capacitor network which receives the sampled-and-held input signals at the normal sample rate. The network includes two separate capacitors controlled by switches operable at two alternating clock phases and connected to provide the desired summation and holding of charges. Feedback leads connected between the amplifier output lead and its noninverting input lead and containing additional capacitors cooperate with the input network to produce an output signal that is sampled-and-held at twice the sample rate of the input signal.
TL;DR: In this paper, a general technique for realizing Bruton's LDI transformation in low-pass switched-capacitor ladder filters is presented, which results is switched capacacitor integrators that are insensitive to parasitic capacitances.
Abstract: A general technique for realizing Bruton's LDI transformation in low-pass switched-capacitor ladder filters is presented, which results is switched-capacitor integrators that are insensitive to parasitic capacitances. It is shown that the correct filter response may be obtained by realizing only the stable poles of the LDI transformed LC network. Realization of these "stable" poles is reduced to the problem of solving a system of nonlinear equations. The design of a third-order Chebyshev low-pass filter is presented as an example.
01 Dec 1980
TL;DR: Four independent real-time programmable switched-capacitor filters have been fabricated on a single NMOS chip and includes permanent programming capability as well as an on-chip oscillator.
Abstract: Four independent real-time programmable switched-capacitor filters have been fabricated on a single NMOS chip. The filters are second-order sections with digitally programmable Q and center frequency. Either low-pass or bandpass functions are available by selecting the appropriate input. The device is microprocessor compatible and includes permanent programming capability as well as an on-chip oscillator. The circuit implementation, programming capability, and operation are described.
Patent•
20 Mar 1980
TL;DR: In this article, a three-phase transducer is connected to the supply line and supplies a signal in direct proportion to the VARs of a double setpoint meter relay.
Abstract: A control system for automatically adding and subtracting capacitors to and from an electrical supply line for regulating the power factor of the supply line. A three-phase transducer is connected to the supply line and supplies a signal in direct proportion to the VARs of the supply line to a double setpoint meter relay. The meter relay is connected to a pair of timing relays which are selectively energized in response to a capacitor "add" or "subtract" signal from the transducer. If the signal is maintained for a predetermined period of time on one of the timing relays, a motor of a respective "add" or "subtract" cam-actuated switch is activated. The cam switches are programmed to energize or deenergize control relays, which in turn actuate capacitor contactors to add or subtract the next available capacitor. The cam switches are in independent circuits so that the cycling of each capacitor is in a next-one-available cycle, whereby the first capacitor added is the capacitor which was removed the longest from the supply line, and the first capacitor removed is the capacitor which has been energized the longest. This sequence provides uniform usage of all the capacitors and the associated controls.
TL;DR: In this paper, an improved apparatus for the linear predictive coding of human speech is presented, in which the speech is sampled through the use of analog filters, and the LPC computations are performed with respect to such samples using digital techniques.
Abstract: Improved apparatus for the linear predictive coding of human speech in which the speech is sampled through the use of analog filters and the linear predictive coding computations are performed with respect to such samples using digital techniques. The filters are MOS switched capacitor filters which can be implemented on a silicon chip together with the digital circuitry. Specific circuits for implementing two different linear predictive coding speech analysis techniques are disclosed.
TL;DR: It is shown that the noise generated in a passive first-order switched-capacitor lowpass filter has its origin in the thermal noise of the m.o.s. transistors' on-resistance.
Abstract: It is shown that the noise generated in a passive first-order switched-capacitor lowpass filter has its origin in the thermal noise of the m.o.s. transistors' on-resistance. The spectral description of this noise at the output of the filter is given. The measurements made on a discrete laboratory model show good correspondence with the analytical results and confirm the noise model established.
Patent•
05 Dec 1980TL;DR: An integrator for use in a switched capacitor filter is described in this article, in which switching elements are connected to an input and to an output of an operational amplifier included in the integrator to clamp the input and output to a ground potential during suspension of the integral operation.
Abstract: An integrator for use in a switched capacitor-filter, in which switching elements are connected to an input and to an output of an operational amplifier included in the integrator for clamping the input and output to a ground potential during suspension of the integral operation, in order to prevent potentials at the input and output of the operational amplifier from varying and hence ensure rapid stabilization of the integral operation of the integrator.
Patent•
10 Jun 1980TL;DR: In this article, a VAR generator of the switched capacitor controlled reactor type is used for a power transmission system, where the thyristor controlled capacitor and reactor banks are kept switched out for small terminal voltage variations which can be tolerated without compensation in order to minimize standby or no load losses in the region of the nominal voltage of the transmission system.
Abstract: A VAR generator of the switched capacitor controlled reactor type is shown utilized for a power transmission system. The control arrangement is such that the thyristor controlled capacitor and reactor banks are kept switched out for small terminal voltage variations which can be tolerated without compensation in order to minimize standby or no load losses in the region of the nominal voltage of the transmission system. Outside of this region VAR compensation is provided.
Patent•
22 Sep 1980
TL;DR: In this article, a switched capacitor filter is designed utilizing two parallel switched capacitor charge pumps, which operate out of phase with each other, thereby allowing charging of a storage capacitor at a rate equal to twice the clock frequency, thereby decreasing incremental voltage steps during the charging of the storage capacitor.
Abstract: A switched capacitor filter is designed utilizing two parallel switched capacitor charge pumps. These two, parallel charge pumps operate out of phase with each other, thereby allowing charging of a storage capacitor at a rate equal to twice the clock frequency, thereby decreasing incremental voltage steps during the charging of the storage capacitor.
Patent•
30 Jul 1980TL;DR: In this article, a switched-capacitor filter circuit has at least one simulated inductor and an operational amplifier with a capacitor interconnected between its output and inverting input and a non-inverting input connected to a reference potential.
Abstract: A switched-capacitor filter circuit having at least one simulated inductor and having an operational amplifier with a capacitor interconnected between its output and inverting input and a non-inverting input connected to a reference potential has a switch leading from the inverting input of the amplifier to a first circuit node from which a first capacitor is connected to the reference potential and also from which a second switch leads to a second circuit node from which another capacitor is connected to the reference potential, and has a third switch leading from the second circuit node to the inverting input of the amplifier and a fourth switch connected between the output of the amplifier and the second circuit node and a fifth switch connected to an input terminal Each of the switches is controlled by one of a series of sequential non-overlapping clock pulse voltages with the first and fifth switches being simultaneously closed followed by sequential closing of the second, third and fourth switches
Patent•
14 Jan 1980TL;DR: In this article, a feedback capacitor (24) in a feedback loop (20) was used to compensate off-voltage voltage compensation for the signal input terminal (14), which was grounded by an electronic MOSFET switch (34).
Abstract: Offset voltage compensation is provided by a feedback capacitor (24) in a feedback loop (20). For periodically resetting the compensation, the signal input terminal (14) is grounded by an electronic MOSFET switch (34). Other such switches (22, 26) close the feedback loop (20) in front of the capacitor (24) and connect the output side of the capacitor (24) to ground for recharging. An input capacitor (30) for compensating the switching feed-through charge of the feedback loop switch (22) is connected between the input signal source (32) and the signal input terminal (14). The ratio of the inherent capacitances of the switches (22, 34) is equal to the capacitance ratio of their respective capacitors (24, 30). Also disclosed is a particularly advantageous method for operating the switches. For switching from the reset condition back to the transmit condition, first the feedback loop switch (22) is opened. Thereafter, the other switches (26, 31, 34) are operated.
TL;DR: In this paper, a bilinear z-transform-based switched-capacitor integrator is proposed, in which the sampled-data transfer function is related to that of a continuous-time integrator by the biliniear z transform.
Abstract: A novel switched-capacitor integrator is discussed, of which the sampled-data transfer function is related to that of a continuous-time integrator by the bilinear z-transform. In contrast to the structures presented so far in the literature, influence of the parasitic capacitances is here reduced by the open-loop gain of the operational amplifier.
TL;DR: A new element, the switched-capacitor transconductance, is developed and used to construct several other active switched-Capacitor building blocks: amplifiers with gain defined by the ratio of capacitors, integrators, inductors, and gyrators.
Abstract: A new element, the switched-capacitor transconductance, is developed and used to construct several other active switched-capacitor building blocks: amplifiers with gain defined by the ratio of capacitors, integrators, inductors, and gyrators. The element is also used to design a switched-capacitor biquad. All reported networks were fabricated with discrete components and tested. Experimental data for the biquad are given.
TL;DR: The filter was constructed with the combined technology of bucket brigade devices and switched capacitors to provide for a large variety of adaptive convolutional and correlative signal processing with optimum compromise among power dissipation, computational speed, size, and performance.
Abstract: Implementation, measurements, and characteristics of a fully integrated 32 tap real-time programmable transversal filter, which facilitates a number of filter applications, are discussed. It uses RAMs and 16 MDACs for tap weight programming and pipe organ structure to provide for a large variety of adaptive convolutional and correlative signal processing with optimum compromise among power dissipation, computational speed, size, and performance. The filter was constructed with the combined technology of bucket brigade devices and switched capacitors.
TL;DR: In this paper, a new switched-capacitor floating inductance simulation circuit which does not depend on matching of passive elements is presented and a source termination circuit which functions as a sample-and-hold circuit for a filter is also described.
Abstract: A new switched-capacitor floating inductance simulation circuit which does not depend on matching of passive elements is presented. A switched-capacitor source termination circuit which functions as a sample-and-hold circuit for a filter is also described.
TL;DR: Modifications of the basic circuit are proposed to cancel the effects of parasitic capacitances and to reduce the chip area, realizing a moderate to high Q frequency emphasizing network.
Abstract: A new switched capacitor circuit is presented, realizing a moderate to high Q frequency emphasizing network. The original feature of this circuit is that its resonant frequency is equal to one half of the sampling frequency, and independent of the accuracy of the capacitor ratio or of any imperfection, both affecting only the Q factor. The gain is nearly proportional to the Q factor. An experimental circuit has been implemented in CMOS Si-gate technology with a programmable gain of 20 dB and 40 dB, corresponding to a Q factor of 8.6 and 79, respectively. Experimental results are in good agreement with the theory. Modifications of the basic circuit are proposed to cancel the effects of parasitic capacitances and to reduce the chip area.
Patent•
01 Oct 1980
TL;DR: In this paper, an operational amplifier is designed to eliminate the effects of inherent voltage affects when used as a voltage comparator, while maintaining a high slew rate and a fast response time by providing a feedback capacitor which can be connected and disconnected between the output terminal and the noninverting current mirror input leg.
Abstract: An operational amplifier is designed to eliminate the effects of inherent voltage affects when used as a voltage comparator, while maintaining a high slew rate and a fast response time by providing a feedback capacitor which can be connected and disconnected between the output terminal and the noninverting current mirror input leg.