Showing papers on "Cascade amplifier published in 1994"

A compact power-efficient 3 V CMOS rail-to-rail input/output operational amplifier for VLSI cell libraries

Abstract: This paper presents a two-stage, compact, power-efficient 3 V CMOS operational amplifier with rail-to-rail input and output ranges. Because of its small die area of 0.04 mm/sup 2/, it is very suitable as a VLSI library cell. The floating class-AB control is shifted into the summing circuit, which results in a noise and offset of the amplifier which are comparable to that of a three stage amplifier. A floating current source biases the combined summing circuit and the class-AB control. This current source has the same structure as the class-AB control which provides a power-supply-independent quiescent current. Using the compact architecture, a 2.6 MHz amplifier with Miller compensation and a 6.4 MHz amplifier with cascoded-Miller compensation have been realized. The opamps have, respectively, a bandwidth-to-supply-power ratio of 4 MHz/mW and 11 MHz/mW for a capacitive load of 10 pF. >

Microwave doherty amplifier

Abstract: An improved Doherty amplifier for operation at microwave frequencies using microstrip circuit technology and gallium arsenide devices to achieve greater efficiency and linearity. The circuit divides the input power equally between a carrier amplifier and peak amplifier with a quarter-wave delay at the input to the peak amplifier insuring that the output power of the two amplifiers will be in phase at the load. A three-port network combines the phase-delayed carrier amplifier output with the output of the peak amplifier. The outputs of the two amplifiers are connected together by a quarter wave transmission line of impedance R. A load of one-half the optimum load (R/2) is attached to the output of the peak amplifier. A quarter-wave line section provides the transition from R/2 to the desired impedance, R. When the peak amplifier is off, its output impedance is infinite and the output power of the carrier amplifier is delivered entirely to the load. As the peak amplifier becomes more active, it delivers more of its output power to the load while its output current gradually reduces the effective load impedance seen by the carrier amplifier thus allowing it to deliver more power. In this way the microwave Doherty amplifier allows 6 dB of linear power amplification beyond the point where a normal Class "B" amplifier begins to saturate and the microwave amplifier efficiency remains close to the maximum attainable linear efficiency.

Self-regulating multiwavelength optical amplifier module for scalable lightwave communications systems

Abstract: In a multiwavelength lightwave communications system automatic self-power regulation on a channel-by-channel basis is achieved with a cascade of multiwavelength amplifier modules (200), wherein each multiwavelength amplifier module in the cascade includes a plurality of pump-shared parallel fiber amplifiers (208) operated in gain-saturation and connected between an optical demultiplexer (203) and multiplexer (209). An optional first gain stage (202) improves performance with higher optical signal-to-noise ratio. By self-regulating the power in each channel, the communications system is scalable, allowing the system to grow without deleterious effects due to power spread.

Adaptive class AB amplifier for TDMA wireless communications systems

Abstract: In a TDM/TDMA portable radio communications system, the modulated RF signal transmitted by a portable handset unit is amplified for uplink transmission to a port by an adaptive class AB power amplifier. A class AB amplifier provides the necessary amplification for the low power levels to be output by the portable units, but must be biased just slightly "on" with no signal input for required maximum efficiency and linearity. In order to maintain the amplifier at a proper bias level over changing temperature conditions and free from the effects of device aging and device-to-device variations, the drain current of the amplifier is monitored each frame outside the burst interval in which the portable is transmitting and thus when no signal is present at its input. The drain current is then controlled by adjusting the gate voltage to compensate for any variations.

Dual mode transmission system with switched linear amplifier

Abstract: A dual mode transmitter circuit is disclosed including a non-linear high-power amplifier having an amplification that can be adjusted and a linear high-power amplifier A first switch and a second switch are connected to the input and output of the linear, high-power amplifier An amplification-adjustable, high-frequency transmitter control amplifier is connected to the input of the non-linear high-power amplifier Apparatus for measuring transmission power such as a directional coupler is connected to the second switch, and a duplex filter is connected to the directional coupler A power level control circuit is responsive to the measured transmission power from the directional coupler and to a power level signal The power level signal is representative of the desired output power of the transmitter The power level control circuit compares the measured power level from the directional coupler with the desired power level and produces a difference signal on its output lead which is connected to both the non-linear high-power amplifier and to the high-frequency transmitter control amplifier A mode selection signal, for designating either an analog or digital type transmission mode is applied to a mode control circuit that is responsive to the mode selection signal and provides switching signals to the first and second switches and a control signal to the linear amplifier The mode selection signal sets the transmitter to function in either the non-linear transmission (analog) mode or the linear transmission (digital) mode

Differentially pumped optical amplifer and mopa device

Abstract: An optical amplifier semiconductor device which is differentially pumped and a master oscillator power amplifier (MOPA) device employing such an amplifier. The amplifier allows the light propagating therein to diverge along at least part of its length, and may be a flared amplifier having a gain region that increases in width toward its output at a rate that equals or exceeds the divergence of the light. The amplifier is pumped with a current density at its input end which is smaller than the current density used to pump the output end for maintaining coherence of the beam to high power levels. Differential pumping may be both longitudinal and lateral within the amplifier. A single mode preamplifier section may be optically coupled to the input end of the amplifier. The amplifier input may have a width which is the same as or wider than that of the preamplifier output. The preamplifier may have a constant mode width or may be tapered to alter the divergence of the beams provided to the amplifier section. The laser oscillator in the MOPA device may be a single mode DBR laser diode monolithically integrated on the same substrate as the optical amplifier. Laser sources external to an amplifier chip may also be used. The input portion of the amplifier or the preamplifier section, if present, may be modulated. The laser oscillator might also be modulated if it has a high Q cavity. Tunable laser oscillators are also disclosed.

Radio frequency signal power amplifier combining network

Abstract: A dual-mode RF signal power amplifier combining network is comprised of two branches, each having a power amplifier (200 and 201). The first branch contains a non-linear mode power amplifier (200) while the second branch contains a linear mode power amplifier (201). The non-linear mode branch also has an RF switch (210). Both branches are coupled to a common output node (220). The common node (220) is coupled to a filter (107) before going to an antenna (106). The non-linear mode power amplifier (200) operates when an FM signal is to be amplified, while the linear amplifier (201) is biased in an off state. The linear mode power amplifier (201) operates when a digital signal is to be amplified, while the non-linear amplifier (200) is biased in an off state. The RF switch (210) removes the non-linear amplifier (200) from the circuit to prevent loading the on state linear amplifier (201).

Energy resolving X-ray detector

Abstract: An energy-resolving x-ray detector for soft x-rays produced by elements having atomic numbers ranging from 9 to 23 includes a charge-coupled integrated circuit radiation detector device having an array of collection regions in a parallel plurality of collection shift registers forming columns of the array; an output amplifier for sequentially amplifying and signalling the charges received by the collection shift register; and a row shift register connected between the collection shift registers and the output amplifier; and a clock circuit having a multi-phase column output connected for sequentially shifting charges between collection regions of the collection shift register and into the row shift register during continuous exposure of the array to incoming radiation, each of the charges received by the output amplifier being sequentially accumulated in each of the collection regions of one collection shift register in response to the radiation, the clock circuit also having a multi-phase row output connected for sequentially shifting the charges from the row shift register to the output amplifier, the output amplifier having a reset connection to the clock circuit for momentarily resetting the input to the output amplifier at a predetermined level prior to receipt of each of the charges into the output amplifier. The output amplifier feeds an analog signal chain providing correlated double sampling. A spectrometer and thickness measurement apparatus suitable for monitoring silicone coatings includes the detector.

Two mode sense amplifier with latch

Abstract: A sense amplifier apparatus for use in a memory array having a plurality of memory cells is provided. The sense amplifier apparatus includes a differential sense amplifier and a dynamic sense amplifier. The differential sense amplifier has a first set of switches for driving the voltages of the sense amplifier apparatus and are coupled to a complementary pair of outputs. Also provided are a second set of switches, which are coupled to a complementary pair of input lines so as to amplify the input signal on either of the pair of input lines to a first signal level at a first rate of amplification. The dynamic sense amplifier shares the first set of switches with the differential sense amplifier and further includes a third set of switches that are coupled to a complementary pair of input lines and the output lines and also a sense enable line. This allows the first signal level to be amplified to a second signal level at a second rate of amplification faster than the first rate of amplification.

Dynamic random access memory having sense amplifier control circuit supplied with external sense amplifier activating signal

Abstract: The present invention relates to a high-speed data transmission system for efficiently transmitting large amounts of data within short periods of time. A DRAM comprises at least a memory cell, sense amplifiers, a /RAS signal input, a word line (WL) boost signal generator, a sense amplifier control signal-generator, and a sense amplifier drive signal-generator, wherein the memory cell is constituted by a plurality of banks, the sense amplifiers are provided in a corresponding plurality of numbers, the sense amplifier control signal-generator are provided in a plurality of numbers to correspond to the plurality of banks, and provision is made of external sense amplifier activating signal terminals which are connected to the sense amplifier control signal-generator in order to activate the sense amplifiers independently of the /RAS signal.

Communication apparatus using common amplifier for transmission and reception

Abstract: A communication apparatus for use in a portable telephone is disclosed which has a transmit-receive common amplifier for amplifying a transmitted signal or received signal, and a mixer for frequency-mixing the transmitted signal or the received signal with a local oscillator output, wherein connection between the mixer and an input side of the amplifier and connection between the mixer and an output side of the amplifier are made by means of respective signal-path selector switches. During reception, a deep bias is applied to an FET of the transmit-receive common amplifier to reduce current consumption, and during transmission, a shallow bias is applied to the FET of the transmit-receive common amplifier for increased output.

Method and apparatus for providing transmitter protection

Abstract: An RF transmitter protection circuit for providing protection to a power amplifier includes circuitry for sensing the presence of an input excitation signal applied to the input of the power amplifier. Circuitry is provided for monitoring an output signal generated by the power amplifier at the output of the power amplifier and for generating a signal proportional to the output signal. Circuitry is further provided for applying the signal generated by the monitoring circuit to the input of the power amplifier in response to a loss of input signal detected by the sensor.

Multiple clocked dynamic sense amplifier

Abstract: A method and circuit is provided for reading a memory array which utilizes multiple clocking signals during one read cycle to enable a dynamic sense amplifier to read data from the memory array. A dynamic sense amplifier is connected to an input line, a complementary input line, and a latch. A first equilibrating signal is input into the sense amplifier, followed thereafter by a first clocking signal. The first clocking signal enables the sense amplifier to read data on the input line and complementary input line. While the sense amplifier reads the data, the sense amplifier is isolated from the input and complementary input lines. Based upon the data read by the sense amplifier, an output state is provided for the latch. After reading the data, the sense amplifier is reconnected to the input and complementary input lines. A second clocking signal then enables the sense amplifier to read the data on the input and complementary input lines a second time, and the sense amplifier is isolated from the input and complementary input lines. The output state of the latch may or may not change based upon the data read by the sense amplifier the second time.

Control of attenuation and amplification in foward and feedback paths for power control for cartesian amplifiers

Abstract: A Cartesian amplifier is provided with a means of controlling its output power comprising a controllable attenuator in the amplifier forward path and a controllable amplifier in the feedback path. A control signal representing the required power level is applied to the attenuator and controllable amplifier and, in response thereto, the degrees of attenuation and amplification are varied in inverse proportion to one another.

Semiconductor memory device employing sense amplifier control circuit and word line control circuit

Abstract: A semiconductor memory device capable of reducing power consumption has a memory cell array, a plurality of address lines, a pair of data lines, an address transition detector circuit for outputting an address transition signal in response to a change in a signal on the address line, a sense amplifier, a sense amplifier control circuit for activating the sense amplifier in response to the address transition signal and deactivating the sense amplifier in response to the sense amplifier output signal, and a word line control circuit which deactivates the word lines within the memory cell array in response to the sense amplifier control circuit.

Sense amplifier circuitry

Abstract: Sense amplifier circuitry (SC) includes a differential amplifier (A) having a reference input and a memory input. The output of a first sense amplifier (SA1) is coupled to the reference input of the differential amplifier (A) and to the input of a second sense amplifier (SA2). The output of the second sense amplifier (SA2) is coupled to the memory input of the differential amplifier (A) and to the input of the first sense amplifier (SA1). The first sense amplifier (SAR) and the second sense amplifier (SA2) include identical mirror transistor circuits (M1, M2, M3, M4).

Method and circuitry for controlling start-up characteristics of a magnetic amplifier control circuit

Abstract: Start-up control circuit (152) regulates the output voltage (Vos) of a power supply circuit (150). Magnetic amplifier control circuit (54) includes magnetic amplifier (42) and error detection circuitry (58, 68, and 70). Start-up control circuit (152) includes sensing circuitry (176 and 184) for generating sensing signals in response to voltage levels (VCC and VEE) in error detection circuitry (58, 68, and 76). Sensing signals indicate whether error detection circuitry (58, 68, and 76) voltage levels are sufficient to drive magnetic amplifier control circuit (54). Reset circuitry (190 and 192, and 194) associates with the sensing circuitry (76 and 184) for initially resetting magnetic amplifier (42) to prohibit output voltage (VOS) from power supply circuit (150) when the sensing signals indicate that voltage levels are insufficient for error detection circuitry to drive magnetic amplifier control circuit (54). Reset circuitry (190 192, and 194) further associates with reset control transistor (76) for controllably decreasing the reset of magnetic amplifier (42). Reset circuitry (190, 192, and 194) further associates with magnetic amplifier control circuit (54) for shifting control of magnetic amplifier (42) to magnetic amplifier control circuit (54) as voltage levels increase sufficiently for the error detection circuitry (58, 68, 70 and 76) to drive magnetic amplifier control circuit (54).

Self-configurable, dual bridge, power amplifier

Abstract: A self-configurable, dual bridge, power amplifier has a window comparator sensing the level of input signals fed to the amplifier which drives a plurality of configuring switches capable of configuring the amplifier as a single bridge amplifier driving a first and a second loads connected in series or as two distinct bridge amplifiers each driving one of the two loads. As long as the two levels of the input signals remain comprised between a range defined by a negative voltage reference and a positive voltage reference, the amplifier is configured as a single bridge driving the two loads in series, thus reducing sensibly power dissipation.

Radio communication apparatus in which output power is controlled by pulse width modulation using a mobile attenuation code

Abstract: A radio communication apparatus capable of varying the level of its transmission output, includes a receiving circuit, a transmitting circuit, an amplifier, an extractor, a detector, a variable voltage converter and a control circuit. The receiving circuit receives a signal from a second station such as a base station, and the transmitting circuit transmits a signal to the second station. The amplifier amplifies the output signal obtained from the transmitter, and the extractor extracts data from the output signal of the receiving circuit so as to control the level of the transmission output. The detector detects the level of the transmission output obtained from the amplifier, and the variable voltage converter converts a source voltage into the operating voltage of the amplifier. The control circuit produces a control signal to control the magnitude of the operating voltage supplied from the variable voltage converter to the amplifier in response to both the detection signal from the detector and the output signal from the extractor, and supplies the produced control signal to the variable voltage converter. The transmission output obtained from the amplifier is varied by changing the operating voltage supplied from the variable voltage converter to the amplifier.

A differential amplification circuit wherein a DC level at an output terminal is automatically adjusted and a power amplifier wherein a BTL drive circuit is driven by a half wave

Abstract: A power amplifier with highly efficient power consumption with fewer switching power supplies. The power amplifier comprises a first differential amplifier having two input terminals and a common terminal, a BTL amplifier consisting of a first SEPP OCL and a second SEPP OCL, a nonlinear adder, an adder, a second differential amplifier, and a switching power supply.

Variable gain amplifier having n parallel-connected elementary amplifiers

Abstract: A variable gain amplifier which has n parallel-connected elementary amplifiers, and components for selecting j-order (j=1, 2, . . . , n) elementary amplifier according to the desired gain. Each elementary amplifier is of a common base type. The variable gain amplifier includes components that are used to obtain a low value input impedance that is independent of the gain of the selected elementary amplifier. The variable gain amplifier will find particular application at the input stages of amplification lines of receiving circuits which require noise performance characteristics.

Design of high-performance power-distributed amplifier using Lange couplers

Abstract: An innovative topology of distributed amplifier based on input and output Lange couplers is presented. The modified operation mechanism of the new configuration, in comparison to the conventional distributed amplifier, determines a remarkable improvement of the output power, power-added efficiency, and small signal gain. The principle of the new amplifier topology, the theory, and several analytical results are discussed extensively. In addition, an accurate study and comparison between the performance of the Lange coupler distributed amplifier and the conventional distributed amplifier confirm the advantages of the configuration suggested. The Lange coupler distributed amplifier will be proved suitable in either large or small signal, as well as wide or narrowband applications. >

A low-noise baseband 5-GHz direct-coupled HBT amplifier with common-base active input match

Abstract: This paper reports on an HBT direct-coupled 2-stage amplifier that uses active common-base input matching to provide multi-decade frequency performance from dc to 5 GHz. This work benchmarks the first reported HBT noise results of an HBT amplifier using common-base active input matching. The 2-stage amplifier consists of a common-base input stage that is directly coupled to a Darlington feedback amplifier output stage. The common-base input can he bias tuned to achieve >13-dB return loss at 3 GHz and a minimum noise figure of 2.9 dB at 1 GHz. A gain of 17.5 dB with a 3-dB bandwidth greater than 5 GHz was achieved under low-noise input bias. This amplifier topology can be implemented without the use of a complex microwave process, which typically integrates backside vias and microstrip matching components. The compact amplifier consumes an area of 0.82/spl times/0.47 mm/sup 2/, which is 10 times smaller than a previously reported 2.5-4 GHz narrow-band passive matched HBT amplifier with similar noise and gain performance. >

Towards a true current operational amplifier

Abstract: (current input - curren output) operational amplifier structures are described and compared. The first one is a differential-input-single-output device, what fulfills the basic idea about operational amplifiers to provide a high differential gain. The second device is a single-inputdifferential-output amplifier, what allows to exploit it as an adjoint element to the differential-input-single-output voltage operational ‘amplifier in current processing circuits interreciprocal to voltage processing circuits.

Continuous time common mode feedback amplifier

Abstract: A continuous time common mode feedback amplifier CTCMFB (300) is suitable for applications requiring fully differential amplifiers in low voltage supply requirements. Two mirror image, low gain CMOS amplifiers (MP0/MP2 and MP3/MP4) in the CTCMFB (300) define and stabilize the common mode output voltage, Vcm, of the main differential amplifier (102). The transient response of the common mode amplifier (300) can be adjusted independently of the transient response of the main differential amplifier (102), allowing fast transient response to the main differential amplifier.

1.5-μm phase-sensitive amplifier for ultrahigh-speed communications

Abstract: Optical parametric amplifiers provide gain to an input signal in a phase-sensitive fashion; hence the name phase-sensitive amplifiers (PSAs). Recently, quantum-limited PSAs with large gains and phase-sensitive signal amplification at 1.06 μm have been demonstrated.1,2 PSAs possess many properties that make them attractive for use in ultrahigh-speed communications and networks: They do not add any spontaneous-emission noise, and the signal-to-noise ratio is preserved as the signal is amplified. In this sense they make an ideal amplifier with a 0-dB theoretical noise figure.1 They are unidirectional in that the gain exists only for light propagating in the same direction as the pump light in the amplifier. PSAs can be designed for operation at any wavelength; hence the full low-loss window of the fused-silica fiber becomes usable. In contrast, the erbium-fiber amplifier provides gain over a relatively narrow wavelength range (≃40 nm). In a fiber/amplifier line the use of PSAs automatically compensates for the degrading effects of dispersion; there is no need for extra dispersion-compensating devices.3 Short pulses can propagate without significant broadening over distances up to 100 times the dispersion length of the fiber. Moreover, dispersion can be compensated in both the positive and the negative group-velocity-dispersion (GVD) regions of the fused-silica fiber. When used with solitons, PSAs can reduce the Gordon–Haus timing jitter without the need for extra filters.4 Solitons can propagate over long distances without generating dispersive radiation during amplification and decay between the amplifiers.5 The preceding properties can be very useful for upgrading the capacity of the existing 1.3-μm fiber plant.

Cascaded amplifier having temperature compensation

Abstract: A cascaded amplifier is comprised of a number of amplifying stages connected in cascade such as the dual emitter-coupled amplifier shown. A first pair of transistors (14,20) provides limiting amplification and a second pair of transistors (16,18) with degeneration (22,24) provide linear amplification. Each pair of transistors is driven by a current source (28,26) which supplies a current (IT, IT2) proportional to absolute temperature (PTAT). The small signal amplification is then substantially independent of temperature and the value of the limited output is proportional to absolute temperature. This latter effect is countered by including a translinear variable current gain amplifier (54,56,58,60) in the last dual-gain stage of the cascaded amplifier to modify the output voltage in a manner inversely proportional to absolute temperature. A transfer function may thus be provided which is substantially independent of temperature.

Reproducing circuit for magneto-resistive head having an initial amplifying stage, a differential amplifying stage, and means for controlling the time of operation thereof

Abstract: A recording/reproducing apparatus for a magneto-resistive (MR) head having a playback amplifier, including a capacitor for a dc feedback low-pass filter for dc feedback to an initial-stage transistor, and a differential amplifier (gm amplifier), and a switching device for the gm amplifier and for the initial-stage amplifier operable at the time of recording/playback switching. The timing of the switching device is deviated for shortening the switching time interval. To this end, an output of the initial-stage transistor of a playback amplifier for a MR head is compared to reference voltage Vref by a gm amplifier and the low-pass filter is constituted by transconductance gm of the gm amplifier and the capacitance of the capacitor, with the dc output of the gm amplifier being fed back to the base of the initial-stage amplifier. The delay in switching time by the charging of the capacitor caused by the difference in the rise time of the initial-stage transistor and the gm amplifier is deviated by the control signal from a control circuit to control the initial-stage transistor and the gm amplifier.

Automatic transimpedance control amplifier

Abstract: An automatic transimpedance control amplifier (100) is disclosed. The amplifier incorporates an automatic gain circuit (155) which simultaneously and automatically adjusts the value of the transimpedance and the voltage gain at each gain stage of the amplifier (115, 130) according to the input current. The amplifier has wide bandwidth, high sensitivity, and more importantly, wide dynamic range.

Signal processor for infrared camera

Abstract: An analog signal processor for use with an array of uncooled detectors. Each detector has an amplifier associated therewith and each amplifier provides gain. A first circuit (212, 294, 300, 220) is included for compensating for a DC offset of each detector/amplifier pair of the array. A second circuit (250, 294, 300) corrects for variations in the sensitivity of each detector/amplifier pair. As a result, the outputs each of the detector/amplifier pairs in response to a common input signal are equalized. In a specific implementation, additional circuits are included providing global automatic DC level control across the array (270, 280, 294, 300), global automatic gain control across the array (250, 262, 294, 300) and frame-to-frame offset adjustment (212, 230).