Abstract: Sample and hold circuits and methods to reduce distortion. A signal to be sampled is connected across a capacitor through a field effect device, which field effect device is turned off when the sample voltage across the capacitor is to be held. When the field effect device coupling the sample voltage to the capacitor is turned on, the body and gate voltages of the field effect device are made to have a fixed voltage relative to the voltage being sampled, so that the characteristics of the field effect device are unaffected by signal variations during sampling or between samples. Exemplary embodiments are disclosed.

Abstract: A method and apparatus for performing voltage-mode sample and hold functions while avoiding nonlinear charge injection. The method comprises oversampling an input signal and sampling an error signal, not the input signal directly, and through signal processing causing the error signal to be reduced to low amplitude. First order and higher order voltage-mode sample and hold circuitry embodiments are provided.

Abstract: A track and hold amplifier for use in adc-converters comprises in succession an input buffer, a pn-junction switch and a hold capacitor. A feedback is provided between the hold capacitor and the input buffer and means are provided to disable the feedback during the hold mode.

Abstract: A sample and hold circuit that is coupled to a control voltage source and a signal source has a sampling bridge coupled in series between a first resonant tunneling diode. The bridge comprises a plurality of diodes. The sampling bridge couples an input voltage signal that is to be sampled to a holding capacitor when the sampling bridge is forward biased. The bridge substantially decouples the input voltage signal from the holding capacitor when the sampling bridge diodes are reversed biased. The resonant tunneling diodes when reversed biased allow the bridge to be isolated from the control voltage source to allow the holding capacitor to float at the sampled value of the input voltage.

Abstract: A circuit 100, which can be used to perform a sample and hold function, includes a switch 112 with a current patch coupled between an input node VIN and an output node VOUT. A capacitor 114 is coupled to the output node VOUT. A replica device 160 includes a current path coupled between the input node VIN and a supply voltage node VDD. A bootstrap circuit, e.g., including a bootstrap capacitor 164, is coupled between a control terminal of the first switch 112 and a control terminal of the replica device 160.

Abstract: A sample and hold in a switched capacitor circuit with frequency shaping. The sample and hold does not require a pair of large area, power-consuming operational amplifiers and, as such, consumes less power and less area. Preferably, the sample and hold is operable in four different states wherein a different set of switches are closed in each of the four states. The switches are controlled by two clock signals and a plurality of signals derived from the two clock signals, such as four signals derived from the two clock signals. Desirably, the sample and hold with frequency shaping is configured to sample a voltage across a first capacitor while a second capacitor is disconnected from said first capacitor, and is configured to thereafter connect the second capacitor to the first capacitor and possibly discharge at least a portion of a charge held in the first capacitor into the second capacitor.

Abstract: The present invention is directed to an integrated circuit having a current supply circuit for supplying a reference current and a signal current; at least one current copier circuit for creating a copy of the reference current and a copy of the signal current; an amplifying circuit connected to the reference supply circuit, the signal supply circuit, and the current copier circuit. The amplifying circuit is configured with the current copier circuit to compare the copy of the reference current to the signal current and to compare the copy of the signal current to the reference current and to generate a comparison signal based upon the comparisons. The present invention may also include an output circuit connected to the amplifying circuit for receiving the comparison signal and generating an output signal and a current mode circuit for receiving the output signal.

Abstract: The purpose of the present invention is to prevent the charge stored in a hold capacitor from leaking via the switches connected to the electrode of the capacitor, in a sample-and-hold circuit, and to suppress the reduction in the voltage held in the capacitor, thereby improving the performance of the sample-and-hold circuit. The switches connected to the capacitor comprises two N-channel MOS transistors that are connected in series and are simultaneously turned on or off. During the period that the switches are in the OFF state, the potential at the interconnection node of the two transistors (one end of a first transistor) is set so as to be equal to that of the other end of the first transistor. Since the potential difference between the both ends of the first transistor thereby becomes zero, leakage currents via the first transistor is reduced, and charge leakage in the capacitor can be prevented.

Abstract: A signal processor connected to a charge-coupled device includes a plurality of delay lines with different delay times connected to a node on a signal line extending from the charge-coupled device to an output terminal of the signal processor, and a selector connected to the plurality of delay lines for selecting an optimum one of the plurality of delay lines. As a result, an effective signal time period of a time delay-free signal inputted into an input terminal of a selected one of the delay lines is superimposed with a field through time period of a delayed signal reciprocally transmitted through the selected one of the delay lines and returned to the input terminal of the selected one of the delay lines.

Abstract: A sample-and-hold device comprises a sampling transistor (Qech) and a sampling capacitor (Cech), the sampling transistor being off in hold mode in order to prevent the discharging of the sampling capacitor and conductive in sampling mode to apply a voltage to the capacitor that is substantially equal to the voltage (Vech) at its base.

Abstract: The proposed sample-and-hold device using a complementary bipolar technology comprises a follower input stage having an input receiving a voltage Vin to be sampled, at least one sampling circuit having a switching stage to be placed either in a first state called a “follower” state where its output follows the potential at its signal input or in a second state called an “isolated” state where its output is isolated from it signal input, the output of the switching stage being connected to the base of a first follower transistor whose emitter is connected to a terminal of an output sampling capacitor, the sampling circuit furthermore comprising a second transistor, having its emitter supplied by a current source and having its base connected to a potential copying that of the terminal of the output sampling capacitor, and a third transistor controlled by the digital command so as to be crossed by a current when the switching stage is in the <<isolated state>>, and so as to b

Abstract: A sample and hold circuit having a semiconductor with a field effect transistor therein. The field effect transistor has a channel in the semiconductor, a source region in the semiconductor, a drain region in the semiconductor a front-gate disposed over the channel, and a back-gate in the semiconductor under the channel. The front-gate and back-gate are configured to control a flow of carriers in the semiconductor through a length of the channel between the source region and the drain region. A capacitor is connected to one of the drain and source regions. The other one of the source and drain region is configured for coupling to an input signal. A switch is responsive to a sampling signal to electrically connect a constant electrical potential between one of the source and drain regions and back-gate during a tracking phase. In one embodiment, the sample and hold circuit includes a second switch to electrically a second constant potential between the front-gate and one of the source and drain.

Abstract: A waveform track-and-hold circuit receives an analog input signal and generates an analog output signal. The waveform track-and-hold circuit includes a differential separating input stage, a differential separating output stage, first and second charge storage means, and switch means. The first and second charge storage means are coupled between the differential separating input stage and the differential separating output stage, and the switch means are controlled by a logic control signal so as to selectively isolate the first and second charge storage means from the analog input signal. Additionally, the differential separating input stage includes a push-pull input stage connected to the switch means and receiving the analog input signal. In a preferred embodiment, the analog input signal is supplied to the emitters of transistors that form the push-pull input stage, the collectors of the transistors are connected to the switch means, and the transistors are part of current mirror circuits.

Abstract: A voltage sample and hold circuit for use as part of a low leakage charge pump circuit in a phase lock loop (PLL). During an inactive state of the charge pumping function, a MOSFET switch that normally connects the charge pump output to the loop filter preceding the voltage controlled oscillator (VCO) of the PLL is opened, e.g., for open loop modulation of the VCO. Meanwhile, the sample and hold circuit which has sampled the voltage at the input side of the MOSFET switch now maintains that voltage, thereby forcing a zero-voltage difference across the MOSFET switch. This zero-voltage difference virtually eliminates subthreshold leakage current through the MOSFET switch, thereby significantly reducing loss of charge in the loop filter due to such leakage current. This ensures a significantly more constant DC bias at the input to the VCO and, therefore, a more stable output center, or carrier, frequency from the PLL during open loop modulation.

Abstract: The invention comprises a differential sample-and-hold circuit including a differential gain stage. The differential gain stage comprises a control transistor and an output node. The differential gain stage further comprises a primary load coupled between the control transistor and the output node. A hold control circuit is coupled to the base of the control transistor, the hold control circuit operable to effect a reduction of the base voltage of the control transistor and a corresponding reduction of the voltage at the output node of the differential gain stage.

Abstract: The analog sampling circuit samples an analog input signal at intervals of time precisely defined by a master clock signal. The analog sampling circuit comprises N track-and-hold circuits and a clock signal generator. Each of the track-and-hold circuits includes a clock signal input. The clock signal generator includes a clock window signal generator and N gate circuits. The clock window signal generator comprises an input connected to receive the master clock signal, and N outputs, derives clock window signals from the master clock signal and feeds one of the clock window signals to each of the outputs. The clock window signals have imprecisely-timed edges. Each of the N gate circuits generates a sub-sampling clock signal with logic states defined by one of the clock window signals and with edge timings defined by the master clock signal independently of the imprecisely-timed edges of the clock window signal, and comprises a first input, a second input and an output.

Abstract: A method and apparatus for an improved track-and-hold circuit is disclosed. By utilizing an amplifier connected to the input signal in combination with, in essence, a replica of the track-and-hold sampling transistor, a track-and-hold technique that reduces distortion and nonlinearities in the sampling process is achieved.

Abstract: A method and apparatus for detecting a sinusoidal signal samples a received signal. An error signal generator receives at its inputs a previous sample of the received signal and a current sample of the received signal and generates an error signal based on these previous and current samples. A comparison circuit compares the generated error signal for the current sample to an error threshold value and generates a threshold comparison signal with a first value that indicates the generated error signal is below the error threshold value for a second value that indicates a generated error signal is above the error threshold value. A determination circuit then determines whether the received signal is a sinusoidal signal based on a threshold comparison signal generated for a plurality of samples. The determination circuit includes a counter that maintains a count of the number of threshold comparison signals having the first value within a sampling period.

Abstract: In a sample hold circuit (6, 50, 60) capable of relaxing a dependency of a voltage of an analogue input signal on an ON resistance of a switch (2). In the sample hold circuit (6, 50, 60), plural reference voltages VrefN are supplied, and unit switches (11e) forming the switch (2) are selectively activated (an ON state) based on a comparison results (whether or not the voltage of the analogue input signal is greater than each reference voltage) from plural comparison circuits (13e) whose operations are performed based on the voltage of the analogue input signal (1).

Abstract: A method and circuit arrangement for processing analog signals in applications in which low energy consumption is of the essence. An integrator topology where the active charge-transferring element is preferably a source-follower-type transistor in which one input terminal is arranged so as to be substantially independent of the input signal and in which the essential signal path elements of the circuit topology are connected in a fixed manner. Preferably, the circuit arrangement is realized so that it comprises separate transistors for sampling and charge transfer. Thus it is possible to connect an input signal in a fixed manner in an input terminal of the sampling transistor, and an input terminal of the charge-transferring transistor can be connected in a fixed manner to a constant voltage. By using a signal processing circuit according to the invention, it is possible to avoid circuit non-idealities caused by parasitic capacitances.

Abstract: A sample and hold circuit (200) accepts an input (202). During a first half of the clock (204) (either an active high portion or an active low portion) the devices (216, 220, and 222) drive the node (218) to a voltage representative of the voltage present on input (202). At a rising edge of the clock (204), the switch (222) is disabled and the voltage on the node (218) is forced to a higher hold voltage by a capacitor (224). While sample circuit (208) is holding the high voltage on node (218), a hold circuit (210) is settling to a hold voltage representative of the voltage on node (218) in a master-slave fashion. This manner of clocking and controlling the circuit (200) allows circuit (200) to be used in low power, high speed telecommunications systems.

Abstract: A gating circuit for largely glitch-free gating of analog signal values obtained in a periodic sequence, capacitively buffer-stored, digitized by means of an A/D converter and subsequently erased before a next signal value is obtained in the capacitive buffer store. A first operational transconductance amplifier (OTA) capable of being activated by a gating pulse has a non-inverting input connected to the reference-earth point of a capacitive store and an output connected to the charging terminal of the capacitive store. Its inverting input is connected through an impedance converter and a resistor, which limits the discharge current, to the charging terminal of the capacitive store. A second OTA serves as a signal driver whose gain is predetermined by the ratio of the value of a resistor connected in parallel with the capacitive store to that of a series resistor that determines the potential at the inverting input of the second OTA.

Abstract: Level shifter circuits are used to configure analog or multilevel memory cells. A level shifter circuit generates an output voltage that is above the input voltage by an offset voltage value. The magnitude of this offset voltage or the relationship between the input and output voltages of the level shifter is adjustable or programmably selectable. Adjustments can be made after the integrated circuits is fabricated and packaged. Adjustments are made by configuring bits of data in the integrated circuit to indicate the offset voltage or other parameters. These configuration bits are implemented using latches, flip-flops, registers, memory cells, or other storage circuits.

Abstract: Disclosed is a device for the conversion of a series signal received in the form of a low-amplitude, high-frequency differential signal into n parallel signals. The device uses a scheme derived from that of a static memory cell as a sample-and-hold unit and amplifier. The device continues to perform well when the differential signal comprises noise in common mode.

Abstract: An electronic circuit provides automatic compensation with reduced errors of undesirable offsets in analog and digital signals, including offsets in the input signal and offsets due to tolerances in components comprising said electronic circuit. The electronic circuit includes a minimum-hold circuit or, depending on the polarity of the signal of interest, a maximum-hold circuit to continuously determine the at-rest, or reference level of the input signal. The accuracy of compensation is therefore not a function of the duty cycle or amplitude of the input signal of interest.

Abstract: A sample and hold circuit having a single-ended input and a differential output. Switching circuitry operates to couple first and second input capacitors to the single-ended input and to a reference voltage, respectively, when in a sample mode. The switching circuitry also operates in the sample mode to connect a first pair of feedback capacitors between the inputs and outputs of a differential amplifier and to connect a second pair of capacitors between known reference voltages. During the hold mode, the switching circuitry causes the charge present on the input capacitors to be transferred equally to the second pair of feedback capacitors so that the output of the differential amplifier is a differential representation of the single-ended input.

Abstract: There is disclosed a semiconductor device in which capacitor means are connected to multiple input terminals via latch means, and the terminals on one side of the capacitor means are commonly connected to the input of a sense amplifier, thereby attaining a reduction of the circuit scale, improvement of the operation speed, saving of the consumption power, reduction of the manufacturing cost, and improvement of the manufacturing yield.

Abstract: A multi-channel readout chip is provided in which each channel has an analog section and a digital section. Each channel of the readout chip employs low noise charge sensitive amplifier inputs with self triggering output. The trigger threshold can be adjusted to provide energy discrimination. The chip has different, externally selectable, operational modes including a sparse readout mode in which only the channels which have received signals greater than a preselected threshold value are readout. The sparse readout mode results in increased data throughput, thus providing fast data acquisition capabilities.

Abstract: A current comparator comprises first (1) and second (2) inputs for receiving input currents to be compared. During a first phase (1a) of a clock period the input currents are sensed and stored on first (N1,S7) and second (N2,S8) current memory circuits. On a second phase (1b) of the clock period a switching arrangement (S1 to S4) inverts the input currents and applies them together with the currents stored in the first (N1,S7) and second (N2,S8) current memory circuits to a regenerative latch circuit (P1,P2,S9,S10). During a third phase (2a) of the clock period the comparator produces the comparison result at an output (3). During a fourth phase switches (S5,S6,S9,S10,S11) are operated to reset the comparator to its initial state.

Abstract: Circuitry for selectively sampling a reference voltage with a capacitor 403 includes a first switch 505a for selectively coupling capacitor 403 to a source of a first reference signal during a first operating phase and a second switch 505b for selectively coupling capacitor 403 to a source of a second reference signal during a second operating phase.

Abstract: To form a high-speed, high-precision sample hold circuit with the minimum number of elements and low current consumption, there is provided a sample hold circuit including an operational amplifier including differential input stage in which sources or emitters are commonly connected, a cascode current mirror circuit for receiving a differential output from the different input stage, and a push-pull output stage having a diamond circuit connected to the cascode current mirror circuit, wherein a hold capacitor is connected to the output of the operational amplifier, and the push-pull output stage is switched between a buffer operation mode and a high-impedance output operation mode in accordance with a logic signal.

Abstract: A circuit for transferring high voltage analog video signals while enabling the use of conventional low voltage logic levels includes a first transistor powered by a high voltage power source to bias a pass transistor at a high voltage level. The pass transistor receives a high voltage video signal and because of the high voltage bias is able to pass the video signal without attenuation of the signal due to feedthrough effects, thus preserving the fidelity of the video signal. A second transistor provides a ground potential which operates to turn OFF the pass transistor, thus disabling the transfer of the video signal therethrough. A third transistor operatively coupled to the first transistor operates to turn OFF the first transistor when the second transistor is in operation.

Abstract: An input switch for use in a switch-capacitor circuit having unified architecture, and a switch-capacitor circuit including such an input switch, an amplifier, a capacitor between the amplifier and switch, and at least one NMOS transistor. The input switch samples an input potential in a sampling mode, receives a reference potential, and includes a transmission gate having a first NMOS transistor. The switch is configured to prevent the transmission gate from passing the reference to the capacitor when the reference is so low that the difference between the sampled input and reference is below an overdrive-causing level, thereby preventing capacitor charge loss which would otherwise lead to overdrive while the switch-capacitor circuit compares the reference with the sampled input.

Abstract: In order to prevent an output offset voltage from occurring because of a relative difference of threshold voltage Vth between NMOS and PMOS in transmission of dc voltage, a semiconductor integrated circuit is constructed in a circuit configuration comprising a first depletion-mode N-channel MOS transistor and a first depletion-mode P-channel MOS transistor, a gate of each transistor being connected to an input terminal and a source of each transistor being connected to an output terminal, a second depletion-mode N-channel MOS transistor having W/L equal to that of the first depletion-mode P-channel MOS transistor, a drain of the transistor being connected to the output terminal and a gate and a source of the transistor being connected both to a lower-voltage-side power supply, and a second depletion-mode P-channel MOS transistor having W/L equal to that of the first depletion-mode P-channel MOS transistor, a drain of the transistor being connected to the output terminal and a gate and a source of the transist

Abstract: A sample-and-hold circuit configured with a low source voltage for assuring low power consumption. An input signal and an output signal are coupled to one side and to the other side of a current mirror circuit. The input signal is sample-held by a differential circuit adapted to cause the current to flow a desired current to the current mirror circuit and to perform switching of the current mirror circuit and sample clocks entered to the differential circuit. The sample-holding operation is feasible even with a lower voltage source.

Abstract: A monolithically integrated signal processing circuit comprising a signal series branch connected between a signal input terminal and a signal output terminal; a reference potential terminal; a series capacitor inserted in serial manner in the signal series branch and having a parasitic capacitance acting like a capacitor that is connected between a first electrode of the series capacitor directed towards the signal input terminal and the reference voltage terminal; and a first parallel capacitor connected between the first electrode of the series capacitor and the reference potential terminal; with the first parallel capacitor being constituted at least in part by the parasitic capacitance.

Abstract: An analog-to-digital converter (ADC) includes a plurality of capacitors formed on a semiconductor substrate and having actual capacitance values statistically related to desired capacitance values, and a gain stage comprising an amplifier and capacitors selected to provide a more accurate gain for the gain stage. A first at least one capacitor is connected between an input and an output of the amplifier defining a feedback capacitance, and a second at least one capacitor is connected between the input of the amplifier and an input of the at least one gain stage defining an input capacitance. In addition, the ADC includes a connection network selectively connecting the first at least one capacitor and the second at least one capacitor from among the plurality of capacitors to provide a desired ratio of feedback capacitance to input capacitance based upon the actual capacitance values. Accordingly, a gain can be set for the gain stage that is more accurate than would otherwise be obtained.

Abstract: An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node.

Abstract: A signal transfer system (10) includes a driver (12) coupled to a receiver (14) using a signal line (16). The driver (12) drives the signal line (16) from an intermediate voltage (22) to a selected first or second voltage to indicate a transition of the input (18). The use of the intermediate voltage (22) on the signal line (16) reduces the effective switching capacitance, which reduces power dissipated by the signal transfer system (10).

Abstract: The circuits and methods of the present invention provide sample and hold circuits that incorporate an auxiliary sampling leg that cancels distortion produced in a main sampling leg of the sample and hold circuit. The auxiliary sampling leg of the circuit produces canceling distortion that is proportionally larger than the distortion produced in the main sampling leg. The distortion in the auxiliary sampling leg is then reduced in size so that the canceling distortion becomes proportionally equal to the distortion in the main sampling leg. Finally, the proportionally equal canceling distortion of the auxiliary sampling leg is subtracted from the distortion of the main sampling leg so that substantially all of the distortion is canceled out while retaining a substantial portion of the input signal.

Abstract: A method and circuit to regulate a random waveform signal to ensure that the LED indicator driven by the waveform signal is visible to the human eye is provided. The method and circuit first determines whether there is a pulse occurring. If an on-going pulse is detected, the regulated waveform signal is driven HIGH for at least 8 clock cycles. If no on-going pulse is detected, the regulated waveform signal is driven LOW for at least 8 clock cycles.

Abstract: A bootstrap sample and hold circuit accurately acquires and holds values of a high frequency analog input signal, to avoid harmonic distortion of a signal representing the analog input signal in, for example, a pipeline ADC, includes a first sampling MOSFET coupling the analog input signal to a sampling capacitor. A bootstrap circuit includes a bootstrap capacitor. First and second MOSFETs couple the bootstrap capacitor between a first reference voltage and ground in response to pulses of a first clock signal. Third and fourth MOSFETs then couple the bootstrap capacitor between the gate and source of the sampling MOSFET in response to non-overlapping pulses of a second clock signal to apply a constant gate-to-source voltage to the sampling MOSFET, the gate-to-source voltage having a magnitude equal to the difference between a first reference voltage and ground during the pulses of the second clock signal.

Abstract: An integrated sample-and-hold S/H circuit includes a subthreshold conduction current compensation circuit for reducing undesired effects of subthreshold conduction current in a first field-effect transistor (FET) during the holding time. More particularly, the S/H circuit may include a substrate, a sampling capacitor formed on the substrate, and the first FET. The first FET has a first conduction terminal for receiving the input signal, a second conduction terminal connected to the sampling capacitor, and a control terminal. The control terminal is responsive to control signals for connecting the input signal to the sampling capacitor during a sampling time and for disconnecting the input signal from the sampling capacitor during a holding time. The first FET preferably further includes a body which unfortunately creates a parasitic diode connected to the sampling capacitor.

Abstract: In systems embodying the invention, circuitry responsive to first and second, complementary, input signals controls the application of the input signals to a positive signal integrator and to a negative signal integrator. When the amplitude of the input signals is greater than a predetermined value, the one of the two input signals which is positive relative to the other is applied to the positive signal integrator and the other one of the two input signals is applied to the negative signal integrator. When the amplitude of the input signals is smaller than a predetermined level, the circuitry causes the periodic application of the first input signal to the positive signal integrator and the second input signal to the negative signal integrator during one time interval, and the periodic application of the first input signal to the negative signal integrator and the second input signal to the positive signal integrator during a second, subsequent, time interval of similar duration as the one time interval.

Abstract: A wideband sample-hold circuit is formed with a single diode in a minimum component configuration. A gate circuit comprised of a first capacitor and an impedance element forms a gate pulse, stores the sampled signal charge on the first capacitor, and transfers the charge to a second capacitor via the impedance element. The impedance element also defines the gate pulse width, in combination with the first capacitor. In a preferred mode, the first capacitor is responsive to individual gate pulses while the larger second capacitor integrates charge packets from the first capacitor due to multiple gate pulses to provide an integrated baseband output. In radar rangefinder applications, the baseband output is an equivalent time replica of the RF input. The sample-hold circuit has other applications in radar motion sensing and time domain reflectomitry.

Abstract: Method and apparatus for performing voltage sampling. The present invention addresses the problems encountered when a voltage is applied to a voltage sampling circuit (76). An additional capacitor (88) is used to store an amount of charge similar to the amount of charge needed by a primary capacitor (89) which provides an output signal to a voltage receiving circuit (74), such as a portion of a sigma-delta analog to digital converter. The additional capacitor (88) is charged while a primary capacitor (89) is discharged in a first clock phase. Then the additional capacitor (88) and the primary capacitor (89) are both coupled to the voltage to be sampled during a second clock phase.

Abstract: A MOS track-and-hold circuit incorporating cancellation of error due to switch feedthrough is described. To eliminate the channel charge feedthrough due to oxide capacitance, a switched capacitor source (22) is connected to be charged to a voltage V1 during the "hold" phase and between the input node (12) and the switch gate (17) to provide a voltage V1-Vin during the "track" phase. A dummy transistor (26) biased in an "off" condition has its drain connected to the holding capacitor (15) and its gate switched between ground and the output terminal (Vout which tracks Vin) to also cancel the feedthrough from the gate-drain overlap capacitance and any gate-drain parasitic capacitance.

Abstract: A comparator circuit and method for comparing first and second inputs. First and second input capacitors are provided for storing first and second voltages indicative of the first and second inputs when the circuit is in a sample phase. A comparator stage coupled to the first and second input capacitors switches from a measure state to one of first and second output states when the comparator circuit is in a hold phase based upon the relative magnitudes of the first and second inputs. Reset circuitry operates to discharge the input capacitors when the comparator stage switches to one of the output states. During a subsequent sample phase, the discharged input capacitors can be rapidly charged to new voltages thereby increasing the operating speed of the comparator circuit.

Abstract: A level detection circuit, such as a Schmitt trigger circuit, has an input threshold voltage which varies depending upon the detection circuit output. The circuit includes a level detection stage, circuitry for switching the level detection stage between an active and a standby mode and a storage device for storing data indicative of the input threshold voltage when the level detection stage is in the standby mode and for controlling the level detection stage using the stored data so that the stage will retain the same input threshold voltage that existed when the level detection stage was switched to the standby mode.

Abstract: A switched-transconductance circuit for use in a multiplexer circuit includes integrated T-switches to provide isolation between each of the differential voltage inputs of a transconductance stage and: (1) a respective differential current output of the transconductance stage, and (2) the opposite polarity voltage input of the transconductance stage. Each of a pair of first switches, which are enabled only when the transconductance circuit is disabled, is connected between a differential current output of the transconductance stage and a circuit ground. Each of a pair of second switches, e.g., cascode transistors, which are biased to be turned on only when the transconductance circuit is enabled, is coupled between the output of the transconductance stage and an output of the transconductance circuit. A third switch is connected between a common-emitter node of a differential pair of input transistors included in the transconductance stage and a circuit ground.