Abstract: A polarization-mode selective semiconductor laser includes a semiconductor laser structure including an active layer for generating gain spectra for the first and second different polarization modes and a diffraction grating formed with a uniform pitch over the laser structure. The laser structure includes a first DFB reflector portion with a first channel stripe and a second DFB reflector portion with a second channel stripe connected to the first stripe channel. The first DFB reflector portion and the second DFB reflector portion is serially arranged in a cavity direction of the laser.

Abstract: An integrated S/H circuit includes a first field-effect transistor (FET) formed on a substrate with a sampling capacitor, and a buffer amplifier having an input connected to the sampling capacitor and an output connectable to the body of the first FET. The buffer amplifier thereby reduces undesired effects from a parasitic diode formed by the body and sampling capacitor. More particularly, the first FET preferably has a first conduction terminal for receiving the input signal, a second conduction terminal connected to the sampling capacitor, and a control terminal 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 circuit may include one or more switches for connecting the body of the first FET to the output of the buffer amplifier during the holding time to thereby apply a holding voltage from the sampling capacitor to the body of the first FET.

Abstract: A comparator (22) compares the output signal (Vout) supplied by an output amplifier (21) with an input signal (Vin). Dependent on the result of the comparison, it controls the conduction of one or the other of two sources (IGA, IGB) which supply opposite currents. Two complementary assemblies (A, B) each comprise a first transistor (T1A, T1B) and a second transistor (T2A, T2B). Each first transistor (T1A, T1B) has its base controlled by one of the current sources for charging a first capacitance (C1) connected to the output, and also controls the conduction of the corresponding second transistor. The bases of the second transistors (T2A, T2B) are jointly connected to the first capacitance (C1) and their emitters are jointly connected to the negative input of the output amplifier (21). The negative input of the output amplifier (21) is also connected to a reference voltage (Vref) via a resistor (20) and to the output (Vout) via a second capacitance (C2).

Abstract: A peak hold circuit includes an error amplification circuit having a first transistor section receiving an input voltage and a second transistor section constituting a differential error amplifier together with the first transistor section. The second transistor section has a plurality of transistors connected in parallel so as to operate individually. The peak hold circuit also includes a switching circuit having a plurality of switching transistors operated in accordance with an operation voltage of each of the transistors of the second transistor section, a charging circuit including a capacitor, for charging the capacitor stage by stage in accordance with a switching operation of each of the switching transistors of the switching circuit, and an output circuit for outputting a charging potential of the capacitor as a peak value signal of the input voltage.

Abstract: A sampling circuit which is capable of a full ranging output when powered with very low voltage supplies, e.g., of about 1 volt. A current copier function is added to a sample and hold circuit to avoid the need for low threshold switching devices in the sampling circuit, thus avoiding output droop due to the increased leakage of low threshold devices. A pre-charge circuit is placed between the sample and hold circuit and a current storage transistor to `boost` the voltage level of the output of the sample and hold circuit above the threshold voltage of the current storage transistor. The pre-charge circuit includes an output voltage boost capacitor which is charged before the hold cycle of the sampling circuit. The level of the voltage charged onto the output voltage boost capacitor is based on the threshold voltage of the current storage transistor.

Abstract: An A/D converter includes a sample-hold circuit, A/D converting stages connected in series to the sample-hold circuit, and an encoder/latch circuit which adds 3-bit digital signals issued from the A/D converting stages to each other for outputting a signal of 9 bits. The sample-hold circuit and the A/D converting stages each include a differential amplifier. Differential outputs of each differential amplifier are short-circuited for a predetermined initial period in each sampling period.

Abstract: There is provided a time counting circuit which measures a pulse spacing of a pulse signal with a high accuracy and exhibits high resistance to variations in power-source voltage.A delay circuit ring consists of a plurality of delay circuits connected in a ring configuration and signal transition is caused to circulate around the delay circuit ring by oscillation. A switch-signal generating circuit outputs first and second switch signals based on the time at which a pulse signal to be measured rises. A row of sampling circuits consists of a plurality of sampling circuits connected to the output terminals of the respective delay circuits and samples the output signals from the delay circuits in response to a direction indicated by the first switch signal.

Abstract: A fully differential sample-and-hold amplifier 60 includes a common-mode feedback circuit 100 for adjusting the common-mode input so that the common-mode output remains near a desired level. During a first switching state, the sample-and-hold amplifier samples voltages and is coupled to the feedback circuit 100 for the adjustment of the common-mode input level. During a second switching state, sample-and-hold amplifier performs its charge transfer and amplification function while the feedback circuit 100 is not coupled to the sample-and-hold amplifier. During the first switching state, the feedback circuit 100 receives as an input the common-mode voltage of the operational amplifier and outputs an amplification of the difference between the common-mode voltage and a regulating input voltage. The output of the sample-and-hold amplifier is coupled to the common-mode input of the operational amplifier.

Abstract: In a switched-capacitor input sampling structure, a resistor connected in series with the input structure, but after the output of the input switch limits the noise bandwidth of the input structure. The selected placement of the resistor does not appreciably limit the slewing or settling time of downstream circuit elements, resulting in a low noise bandwidth, high speed system.

Abstract: A circuit for generating a threshold voltage level from a time division duplex analog data signal. The circuit comprises a sample/hold circuit and an amplifier. The sample/hold circuit is arranged to sample the threshold voltage level during a reception interval and hold the threshold voltage level during a transmission interval. The amplifier includes an operational amplifier coupled to the sample/hold circuit for amplifying the analog data signal during a reception interval and amplifying the threshold voltage level during a transmission interval. A transconductance device is coupled to the operational amplifier, and a plurality of load legs are respectively coupled to a plurality of bias legs. A first selected pair of the respectively coupled load legs and bias legs is coupled to the transconductance device, and a second selected pair of the respectively coupled load legs and bias legs coupled to the output of the amplifier to provide the threshold voltage level.

Abstract: A sample-and-hold circuit is provided for a switched-mode power supply of the type having a transformer with a primary winding, an auxiliary winding and a secondary winding, with a switching transistor coupled in series with the primary winding and a sample-and-hold capacitor for storing a voltage proportional to an output voltage of the auxiliary winding and coupled to a controlled terminal of the switching transistor in a feedback loop which normally operates in a closed-loop mode for switchably regulating the power supply. To prevent the feedback loop from being driven to an open-loop or "stuck" mode of operation, a discharge capacitor is provided which is switchably coupled in parallel with the sample-and-hold capacitor to discharge excess voltage from the sample-and-hold capacitor and thereby restore the feedback loop to its normal closed-loop operating mode.

Abstract: A diode for passing the output of a differential amplifier to a holding capacitor is short-circuited in response to a first switching signal, thereby causing the holding capacitor to be discharged through the short-circuiting circuit under control of a second switching signal. The first and second switching signals are generated by delaying a reset signal. The first switching signal is terminated before the termination of the second switching signal.

Abstract: A signal sampling circuit for performing correlated double sampling (CDS) of an input signal with a pipelined sample and hold architecture includes a time multiplexed integrating amplifier circuit in which the output circuit is a pipelined sample and hold circuit which provides time multiplexed input signal samples and the feedback integration capacitor is discharged between samples. At all times, one of the channels of the pipelined sample and hold circuit is providing one of the time multiplexed input signal samples while the other channel continues tracking the input signal. The feedback integration capacitor acts as a clamp to null out residual reset noise received as part of the input signal to be sampled. Hence, with the exception of that very brief period of time necessary for switching between the two pipelined sample and hold circuit channels, one of the two pipelined sample and hold circuit channels is always available for signal acquisition.

Abstract: An improved CMOS CDS circuit which can operate on 2.7 volts, provides increased noise immunity and can handle a 0.8 volts maximum signal input. The present invention provides internal capacitors to isolate the input pads. The present invention also provides switches and capacitors to perform a sample and hold function on every pixel value.

Abstract: A low distortion track-and-hold circuit in which a simple, four-transistor amplifier makes the circuit characteristics independent of the source impedance, and compensates for unequal voltage drops caused by mismatched diodes. An additional pair of bipolar transistors is used to eliminate errors caused by switching transients coupled through the diodes. In the track mode, the differential output voltage between two sampling capacitors tracks the differential input voltage of the circuit. At the end of the track time, this differential output voltage is equal to the differential input voltage. During the hold period, the sampling capacitors are isolated from the differential input voltage. The voltages controlling the switching diodes reverse symmetrically during the transition from track to hold, resulting in a cancellation of any feedthrough of the switching transients to the sampling capacitor. Beta and temperature compensation circuits are also included in the differential track-and-hold circuit.

Abstract: A semiconductor integrated circuit device is provided having a low-amplitude input/output interface for inputting or outputting an input/output signal synchronously with a clock signal and transferring the input/output signal with an amplitude corresponding to a power supply voltage to or from an external command unit. A first differential circuit to be practically continuously operated is used as an input circuit for receiving a clock signal supplied from an external clock unit. In addition, a second differential circuit is provided which is intermittently operated in accordance with the clock signal to sample an input signal in accordance with an internal clock signal generated by the first differential circuit while the second differential circuit is operated and holds the sampled signal while the second differential circuit is not operated. This second differential circuit is used as an input circuit for receiving a low-amplitude input signal inputted synchronously with the clock signal.

Abstract: There is provided a correlative double sampling (CDS) device which can effectively and efficiently remove noise from video signal. The CDS device includes at least two sample-and-hold circuits for sampling a video signal output from an image sensor and outputting a predetermined DC level signal, and a differential amplifier. The correlative double sampling device also includes a clamping circuit for DC-clamping a video signal output from the image sensor and applying the DC-clamped signal to the sample-and-hold circuits. At least two re-sample-and-hold circuits are provided for re-sampling the signal output from the sample-and-hold circuits. A level correcting portion is used for correcting the output level of one of the sample-and-hold circuits and one of the re-sample-and-hold circuits, and outputting a signal whose phase is synchronized with the output of the re-sample-and-hold circuits.

Abstract: A current memory cell comprises a first bipolar transistor providing a current source and coupled to the emitters of a second and a third bipolar transistor, the latter forming the storage elements of the memory cell. The memory cell is calibrated, to avoid mismatch between the second and third transistors, by adjustment of the current source via a parallel arrangement of a resistor and a field effect transistor in the emitter circuit of the first transistor.

Abstract: Improved small current detector circuit and locator device each comprise a first and a second element in both of which a small current output occurs, a first and a second constant current generator circuit each generating a specified constant current, a first current mirror circuit which is supplied at the input with said output current occurring in said first element and said specified constant current generated from said first constant current generator circuit, and a second current mirror circuit which is supplied at the input with said output current occurring in said second element and said specified constant current generated from said second constant current generator circuit, and wherein either one of said first and second elements is disposed in a detecting portion and a current equal to the current from the output of either one of said first and second current mirror circuits is flowed to the output of the other current mirror circuit such that a detection output corresponding to the difference betw

Abstract: A low-power differential switching amplifier (200, 210, 220, 230) is provided which utilizes a unique technique of generating interlaced ramps. The interlacing of the ramps causes the ramp discharge time to be effectively zero, which produces exceptionally accurate sawtooth waveforms with virtually no distortion. The timing of the differential switching amplifier circuitry can be synchronized with an external clock. A voltage null point is produced in the differential amplifier where zero voltage at the input of the amplifier produces essentially zero power dissipation within the load, even if the load is low-Q or substantially resistive. Also, by use of a phase balancing technique, residual errors resulting from component mismatches, which would otherwise have imposed power losses upon the load, are nulled out automatically during the operation of the amplifier.

Abstract: The invention is an autozero compensator for use in processing low level signals, the compensator comprising an input integrating operational amplifier providing at its output in one mode an error signal responsively to offset voltage across the differential input terminals of the amplifier. A second amplifier is provided in a feedback loop for generating from the error signal a charge at a compensating voltage equal and opposite to the offset voltage. That charge is capacitively stored and applied to the input amplifier to cancel the offset voltage.

Abstract: In a differential sample-hold circuit used in a serial-parallel type A/D conversion circuit containing a current-added type D/A converter, a pair of differential analog input voltages Vin1 and Vin2 are supplied to a non-inverting input and an inverting input of a buffer amplifier. An non-inverted output and an inverted output of the buffer amplifier are supplied through a pair of switches to one end of a pair of voltage holding capacitors having their other end connected to ground, respectively, and also to an input of a pair of closed-loop buffer amplifiers having their outputs for outputting a pair of differential sampled-and-held voltages.

Abstract: A source driver circuit device for decreasing a gap of output errors of a plurality of driver circuits which perform a serial/parallel conversion of a video signal, comprises a plurality of sample-and-hold circuits arranged in the order for sequentially sampling levels of an input video signal; a plurality of signal output circuits for respectively generating voltage outputs corresponding to holding levels of said plurality of sample-and-hold circuits; a plurality of reference level sample-and-hold circuits each of which is provided with each predetermined number of said sample-and-hold circuits, and for sampling a reference level; a plurality of sample value output circuits for respectively generating voltage outputs corresponding to holding levels of said plurality of reference level sample-and-hold circuits; and an output error correction circuit for performing an output level correction in each of said plurality of signal output circuits on the basis of a level difference between said reference level and

Abstract: A very fast circuit for tracking an input signal and holding the value for digitization comprises a holding capacitor, two charging circuits connected to either side of the capacitor and extending between a constant current generator and a supply voltage. Each charging circuit has an input transistor responsive to an analog input signal and a load including the capacitor, as well as a series switching transistor responsive to a sample signal to permit a tracking mode or forcing a hold mode. The load includes a diode to effect a low resistance during the tracking mode when the capacitor is charging and a very high resistance during the hold mode when the capacitor is discharging.

Abstract: An active matrix liquid crystal drive circuit comprising an input-signal storage capacitor for storing an analog input signal, a differential amplifier which alternately presents a first operative state in which the output thereof is returned to the inverting input terminal thereof in a negative feedback manner and a second operative state in which the output is returned to the non-inverting input terminal thereof through a polarity inverting output buffer circuit in a negative feedback manner, and an output-voltage storage capacitor for storing an output voltage of the differential amplifier. In the first operative state, the voltage stored in the input-signal storage capacitor is applied to the non-inverting input terminal, and the output voltage which is returned to the inverting input terminal in a negative feedback manner is stored in the hold capacitor.

Abstract: A GTL I/O transceiver circuit having a pulsed latch receiver. A pulse generator generates a first pulse and a second pulse within the first pulse in response to a rising edge of the bus clock. The first pulse turns on the differential amplifier of the receiver circuit just long enough to provide a valid amplifier output signal. The second pulse controls a tristate latch such that the value of the amplifier output signal is latched before the differential amplifier is turned off. The pulsed latch receiver turns the differential amplifier on for only a fraction of the period of the bus clock such that power dissipation of the pulsed latch receiver circuit is significantly reduced. By using the pulsed latch receiver in VLSI components having hundreds of I/Os, significant reduction in overall component power dissipation can be achieved and static DC power is eliminated. The GTL I/O transceiver is useful for interfacing VLSI CMOS components to a terminated bus.

Abstract: A current comparator arrangement has first and second inputs (100, 103), an output (105), and cross-coupled transistors (MP1, MP2) which form a latching circuit. The arrangement also includes current stores (MP3, MP4), the input currents to be compared being fed to the current stores in a selected forward differential order for storage therein during a first portion of a clock period in which the cross-coupled latching circuit is reset. During a second portion of the clock period the input current connections are reversed, thereby reversing their differential order, and the reverse order currents are supplied together with the stored forward order currents to the latching circuit. This cancels common mode and offset currents so that they do not affect the comparison of the input currents.

Abstract: A sample-and-hold circuit comprises an analog signal control circuit for supplying a potential of an input signal to one end of a hold capacitor, a first transistor having a base connected to the one end of the hold capacitor and operating in an emitter follower fashion, an amplifier having a second transistor having a base connected to an emitter of the first transistor, and a leak current compensating circuit including a third transistor having an emitter connected to a collector of the first transistor and a current mirror circuit for supplying to the base of the first transistor the same current as a base current of the third transistor.

Abstract: A track-and-hold circuit that utilizes the negative of the input signal to improve tracking of the input signal during the track mode. By applying the negative of the input signal to an amplifier node to which the output signal is coupled, the output signal is forced to track the input signal in magnitude and polarity. Single-ended and fully differential embodiments of the circuit are disclosed, as well as embodiments using an operational amplifier and a cascode inverter amplifier. An improved switching scheme reduces delay in the transition from the hold mode to the track mode. A sample-and-hold circuit may be constructed from a pair of the track-and-hold circuits.

Abstract: A semiconductor memory device 200 includes: a memory cell array 101 including a plurality of pairs of bit lines (BL, XBL), a plurality of word lines WL and a plurality of memory cells 100; a decoder 104 for decoding address information to activate one of the plurality of word lines WL in accordance with the address information; precharge circuits 105 for setting each of the plurality of pair of bit lines (BL, XBL) to a predetermined precharge potential; sense amplifiers 110; and potential difference transmission circuits 109 provided between the memory cell array 101 and the sense amplifiers 110. The potential difference transmission circuits 109 hold a potential difference V.sub.d0 between respective pair of bit lines among the plurality of pairs of bit lines (BL, XBL) and transmit the held potential difference V.sub.d0 between the pair of bit lines to a respective sense amplifier 110. The sense amplifier 110 amplifies the potential difference V.sub.

Abstract: A signal processing apparatus comprising a signal holding circuit to hold an input signal from a signal source, a coupling capacitor provided on the signal source side, a connecting circuit to selectively connect the coupling capacitor and the signal holding circuit, and an adding circuit to add the input signal from the signal source on the basis of the signal held in the signal holding circuit. The adding circuit includes a buffer circuit and a switch to selectively connect the buffer circuit and the output side of the coupling capacitor.

Abstract: The detrimental nonlinear charging currents from an analog input signal through an anti-aliasing filter into a sampling circuit can be minimized by using primary and secondary inputs to the sampling circuit. The secondary input is turned on before the primary input and the charge required to charge the parasitic capacitance inside the sampling circuit and to replenish the channeling charge lost in the previous cycle is supplied primarily through the secondary input. Immediately after the secondary input is turned off the primary input is connected to the sampling node, and only the charge required to fine tune the signal into the sampling capacitor is drawn through the primary input. Therefore, most of the non-linear charge injection is passed through the secondary input, and the signal passed through the primary input is used to fine tune the voltage levels inside the sampling circuit during the actual sampling operation.

Abstract: The signals to be measured are transformed in the system to discrete time digital signals by synchronous sampling. These digital signals are then processed by a digital signal processor for vector detection and for computing digital feedback sent to the sampling gates. The analyzer has improved characteristics in the area of linearity, drift and test port signal injection because of its highly optimized architecture based on synchronous sampling with digital feedback. It possesses unique characteristics such as the ability to tune to a harmonic or a subharmonic of the excitation frequency and a good sensitivity in a high impedance environment.

Abstract: A clocked comparator having an input differential amplifier, a sample and hold circuit, and a load stage. The load stage including a first transistor whose channel is connected between a first terminal and a first node, a second transistor whose channel is connected between a second terminal and a second node, a third transistor whose channel is connected between the first node, a third terminal and a fourth transistor whose channel is connected between the second node and the third terminal and a switch between the first and the second terminal. The gates of the first and the fourth transistor are connected to the first terminal. The gates of the second and the third transistor are connected to the second terminal. When the switch is closed the first and the second transistor form a positive differential impedance between the first and the second terminal. When the switch is open the cross-coupled third and fourth transistors form a negative differential impedance between the first and the second terminal.

Abstract: A sample hold circuit comprises a first transistor having its base connected to an input terminal and its collector connected to a voltage supply terminal, series-connected first and second diodes having a cathode of the first diode connected to an emitter of the first transistor, a first constant current source having its one end connected to an anode of the second diode circuit and its other end connected to the voltage supply terminal, a first differential circuit including a first branch connected to the emitter of the first transistor and a second branch connected to the anode of the second diode, a third diode having its cathode connected to the anode of the second diode, a second transistor having its base connected to a connection node between the second diode and the third diode and its collector connected to the voltage supply terminal, a second differential circuit including a first branch connected to the voltage supply terminal and a second branch connected to an emitter of the second transistor,

Abstract: The offset associated with mismatch of a pair of input devices in comparators used in applications such as flash converters is eliminated by using only one input device or transconductance circuit, time-shared between the input and reference signals. The input device converts each signal in succession into a current. A current copier stores one of these currents while the input device produces the other current, and the two currents are then compared by connecting them to a common node. The comparator includes a first switch for switching between an input and reference nodes, and an input device which receives a reference signal from the reference node during a first comparison cycle, receives an input signal from the input node during a second comparison cycle, and converts the input signal and the reference signal to input and reference currents, respectively.

Abstract: A sample circuit (10) maintains linear operation over frequency. A switchable diode bridge (12) passes the analog input signal when enabled to one terminal of a sample storage capacitor (14). The second terminal of the capacitor is coupled through a closed FET switch (16) to a reference node (18). Once the analog input signal is stored across the capacitor, the FET switch opens before the diode bridge disables. When the second terminal of the capacitor floats and prevents any further charge from altering the sample voltage across the capacitor. When the diode bridge is disabled, the sample voltage across the capacitor does not change. The sample voltage may be amplified and digitized for further processing in the cellular system.

Abstract: A sample-and-hold circuit comprises a first buffer stage, a first sampling switch, a sampling capacitor, and a feedback output amplifier for supplying a sampled output signal (Uout). The sampling capacitor is connected to an output of a second buffer stage, which has an input connected to earth. The output amplifier receives feedback via a third buffer stage and a second sampling switch and via a fourth buffer stage and a second sampling capacitor, which together with the first sampling switch are controlled by the same clock signal. The first sampling switch gives rise to clock feedthrough at the non-inverting input of the output amplifier. This clock feedthrough is cancelled by an equal clock feedthrough at the inverting input, so that the sampled output signal is freed from undesired clock feedthrough.

Abstract: An analog to digital (A/D) converter apparatus is disclosed which increases spurious free dynamic range without adding a significant amount of noise. The apparatus includes a sample and hold circuit, a main range A/D converter for converting the sample and hold circuit output into a first digital signal, and a digital to analog (D/A) converter for converting the output of the main range A/D converter to an analog signal which is fed to a summing node. The output of the sample and hold circuit is also fed to the summing node through a first load resistor. The difference between the D/A output and the sample and hold output is generated at the summing node, and this difference is amplified and digitized by a subrange A/D converter. Added circuitry including a bootstrap amplifier and second load resistor are provided to increase the load impedance on the sample and hold output. An embodiment making use of multiple sample and hold circuits connected in parallel using a bootstrap amplifier is also disclosed.

Abstract: A load stage including a first transistor whose channel is connected between a first terminal and a first node, a second transistor whose channel is connected between a second terminal and a second node, a third transistor whose channel is connected between the first node, a third terminal and a fourth transistor whose channel is connected between the second node and the third terminal and a switch between the first and the second terminal. The gates of the first and the fourth transistor are connected to the first terminal. The gates of the second and the third transistor are connected to the second terminal. The load stage also includes a switch connected between the first node and the second node. When the switch is closed the first and the second transistor form a positive differential impedance between the first and the second terminal. When the switch is open the cross-coupled third and fourth transistors form a negative differential impedance between the first and the second terminal.

Abstract: A sample-and-hold circuit is formed in bipolar transistor technology with the aid of clocked and complementary-clocked bipolar transistors in combination with a holding capacitor whose output terminal, in going from sample to hold phases of the clock, undergoes change in voltage .DELTA.V equal to the input voltage samples Vin applied to its input terminal during the sample phases (electrical bootstrapping operation). In particular, an input terminal of the holding capacitor is connected to a clocked input voltage device that ensures that, during the sample phases, the input voltage applied to the input terminal of the capacitor represents the input voltage being sampled, and that during the hold phases of the clock, the input terminal of the capacitor is electrically clamped. An output terminal of the holding capacitor is connected to one of the clocked transistors and to an auxiliary bipolar transistor whose base terminal is controlled by a complementary-clocked voltage-dropping device.

Abstract: A track and hold circuit including an input terminal V.sub.IN, a first node, a second node and a capacitor C.sub.H. A diode D connects between the first node and the input terminal V.sub.H. Circuitry coupled to the first node makes the diode conductive during track mode of operation, indicated by a clock CK being at a first state, and non-conductive during hold mode of operation, indicated by a clock CK being at a second state. A transistor Q3 is coupled between said first node and said second node. The capacitor C.sub.H is connected to said second node. The transistor Q3 is operative to charge the capacitor C.sub.H during track mode and to isolate the capacitor C.sub.H from the input terminal V.sub.IN during hold mode. Additional circuitry coupled to said transistor Q3 senses the clock shifting from said first to said second state to rapidly discharge the inherent base/emitter capacitor of the transistor Q3 to thereby cause rapid turn off of the transistor Q3.

Abstract: A differential track and hold amplifier circuit (200) is provided. The track and hold amplifier includes an input transconductance amplifier (212), an output amplifier (111), and a second transconductance amplifier (214). The track and hold circuit further includes a switching circuit (108) for coupling the output of the input transconductance amplifier to a capacitor (110) in the output stage of the track and hold circuit during track mode, and for decoupling the capacitor from the input amplifier during hold mode. The track and hold circuit further includes a subtractor circuit (103) for reducing a common mode voltage of the output of the input transconductance amplifier, thereby maintaining a stable voltage across the capacitor during hold mode. Further, during hold mode, the second transconductance amplifier acts in a negative feedback configuration to reduce the gain of the input amplifier to attenuate its output signal.

Abstract: The subject of the invention is a differential sampler circuit including a voltage/current converter (1) having two differential inputs (E1a, E1b) and two outputs (S1a, S1b). According to the invention, each of these outputs is linked via an input multiplexer module (2a) to two interposed track-and-hold modules (5a, 6a), in such a way that at any instant one of the track-and-hold modules (5a, 6a) operates in track mode whereas the other (6a, 5a) operates in hold mode. These two modules (5a, 6a) are linked to the output (S4a) of the sampler circuit via an output multiplexer module (7a). This structure makes it possible to double the sampling frequency without increasing the intrinsic speed of the circuit. Each track-and-hold module (5a, 6a) includes an input load (10a, 11a) linked in parallel with a capacitor (C18a, C19a), an output emitter-follower transistor (T20a, T21a), and a switching cell (5-6a). Thus, the high-frequency performance of the circuit is improved.

Abstract: An input terminal is connected to bases of first and second transistors. Collectors of the first and fourth transistors are connected to a power-source terminal. Collectors of the second and third transistors are grounded. A base of the third transistor is connected to an emitter of the first transistor. A base of the fourth transistor is connected to an emitter of the second transistor. One terminal of the capacitor is grounded and the other terminal thereof is connected to emitters of the third and fourth transistors and an input of an output buffer whose output is connected to an output terminal. A collector of a fifth transistor is connected to the power-source terminal and a base thereof is connected to the output terminal. A collector of a sixth transistor is grounded and a base thereof is connected to the output terminal. A first constant-current source is connected to an emitter of the fifth transistor and a base of the fourth transistor.

Abstract: A multiplex system wherein each of the multiplex circuits includes a hold switch and hold capacitor, a standard class A differential amplifier with constant feeding current source, a multiplex switch to selectively isolate each multiplex circuit from the common multiplex line and a second current source supplying much larger current than the constant feeding current source selectively couplable in parallel with the constant feeding current source to the differential amplifier during periods when the differential amplifier is coupled to the common multiplex line.