123 results about "High gain amplifier" patented technology

An automatic gain control (AGC) amplifier including a high gain transimpedance amplifier, a resistive feedback network and multiple transconductance stages coupled in the feedback path of the AGC amplifier. The feedback network receives an input signal and is coupled to the output of the high gain amplifier and has multiple intermediate nodes. Each transconductance stage has an input coupled to an intermediate node of the feedback network and an output coupled to the input of the high gain amplifier. Each transconductance stage is independently controllable to position a virtual ground within the feedback network to control closed loop gain. Each transconductance stage may have a bias current input coupled to a bias current control circuit. The control circuit controls each bias current to vary the gain of the AGC amplifier. The bias currents may be linearly controlled employing a ramp function to achieve a linear in dB gain response.

A microcontroller includes a wide band, high gain amplifier on-chip capable of driving a 32 ohm speaker. The amplifier is controllable by the microcontroller processor to either enable or disable the amplifier and switch between multiple modes of power. In one embodiment, one or more such amplifiers are situated anywhere on the integrated circuit die including at the corners of the die.

A low voltage difference linear voltage regulator realizes the performance targets such as high output voltage precision, high stability and high supply-voltage rejection ratio by using variable slope gm / C filter circuit module at the output terminal of error amplifier. Variable slope mechanism of the filter circuit module reduces static power consumption of the voltage regulator when the regulator is ideal loaded or light loaded, and produces a parasitic pole whose frequency goes to high when the regulator load voltage increases, accordingly to develop unit gain band width of the voltage regulator and strengthen stability of the heavy loaded or full loaded voltage regulator. Moreover, variable current high-gain amplifier stage used in voltage circuit increases slew rate of voltage regulator internal node and improves interaction capability of the voltage regulator.

An automatic gain control (AGC) circuit including a high gain amplifier, a feedback network and two transconductance amplifiers. The feedback network has a first end that receives an input signal of the AGC circuit, a second end coupled to the output of the high gain amplifier and two intermediate nodes. Each transconductance amplifier has an input coupled to a respective intermediate node of the feedback network and an output coupled to the input of the high gain amplifier. The transconductance amplifiers collectively control a position of a virtual ground within the feedback network to control gain of the AGC circuit. The transconductance amplifiers each include an attenuator and a transconductance stage coupled between the feedback network and the high gain amplifier and are configured to operate linearly across a relatively wide input voltage range. The input offset voltage of the AGC circuit varies monotonically with gain of the AGC circuit.

An automatic gain control (AGC) amplifier including a high gain transimpedance amplifier, a resistive feedback network and multiple transconductance stages coupled in the feedback path of the AGC amplifier. The feedback network receives an input signal and is coupled to the output of the high gain amplifier and has multiple intermediate nodes. Each transconductance stage has an input coupled to an intermediate node of the feedback network and an output coupled to the input of the high gain amplifier. Each transconductance stage is independently controllable to position a virtual ground within the feedback network to control closed loop gain. Each transconductance stage may have a bias current input coupled to a bias current control circuit. The control circuit controls each bias current to vary the gain of the AGC amplifier. The bias currents may be linearly controlled employing a ramp function to achieve a linear in dB gain response.

A receiving circuit of a direct conversion system which includes a differential amplifier circuit which amplifies a received signal, a mixer which combines the amplified received signal and an oscillation signal having a predetermined frequency to perform frequency conversion, and a high gain amplifier circuit in which programmable gain amplifiers and filters which eliminate noise of the received signal, are connected in a multistage and which is configured such that an amplification factor is varied according to the level of the received signal. In the receiving circuit, the low noise amplifier is brought to a non-operating state to allow execution of a DC offset cancel operation of the programmable gain amplifier on the pre-stage side of the high gain amplifier circuit. Thereafter, the low noise amplifier is brought to an operating state to allow execution of a DC offset cancel operation of the final-stage programmable gain amplifier.

A transconductor block including a Czarnul tuning network, transconductance resistors, an input voltage follower amplifier, a common mode circuit, PMOS transistors coupled in cascode configuration, an input current source, and high gain amplifiers that drive NMOS transistors at the output. The input voltage follower amplifier receives a differential input signal including a common mode voltage and applies the differential input signal to the Czarnul tuning network. The Czarnul tuning network includes series resistors and is coupled in parallel with the transconductance resistors. The common mode circuit receives the differential input signal and a reference common mode voltage and provides a bias voltage and a common mode feedback voltage. The common mode circuit asserts the common mode feedback voltage to the output PMOS transistors to establish a DC output current and to minimize drift of the common mode voltage of the transconductance block. Also, the bias voltage is level shifted from the common mode signal. The high gain amplifiers maintain the output of the Czarnul tuning network and transconductance resistors at the bias voltage. The high gain amplifiers are coupled to the input current sources and to the NMOS transistors in a negative feedback configuration. The high gain amplifiers drive the NMOS transistors to reflect an output current that corresponds to the input voltage signal.

A receiving circuit of a direct conversion system is provided which includes a differential amplifier circuit which amplifies a received signal, a mixer which combines the amplified received signal and an oscillation signal having a predetermined frequency to thereby perform frequency conversion, and a high gain amplifier circuit in which a plurality of programmable gain amplifiers and a plurality of filters which eliminate noise of the received signal and an unnecessary wave, are connected in a multistage and which is configured such that an amplification factor is varied according to the level of the received signal. In the receiving circuit, the low noise amplifier is brought to a non-operating state to thereby allow execution of a DC offset cancel operation of the corresponding programmable gain amplifier on the pre-stage side of the high gain amplifier circuit. Thereafter, the low noise amplifier is brought to an operating state to thereby allow execution of a DC offset cancel operation of the final-stage programmable gain amplifier.

The invention provides an optical-receiver preamplifier for receiving analog or digital optical signals. The preamplifier comprises a high-gain amplifier A1, an input circuit, a negative-feedback impedor Zf, a low-gain amplifier A2 adjustable in gain and a feedback capacitor Cff, wherein the input circuit takes a photoelectric converter as a main component; the negative-feedback impedor Zf is connected with the reverse input end and the output end of the A1; the feedback capacitor Cff connects the output end of the A2 with the reverse input end of the A1; and the output end of the A1 can be directly connected with the input end of the A2 or can be connected with the input end of the A2 through a buffer. Output signals of the preamplifier are taken out from the output end of the A1 or the output end of the buffer, and can be directly subjected to subsequent signal processing or be further amplified and then subjected to subsequent signal processing.

An optical receiver includes a light receiving element for converting an optical signal to an electrical signal having a first bandwidth and an amplifier for amplifying the electrical signal. The amplifier has a first gain response that yields a second bandwidth that is less than the first bandwidth. The optical receiver also includes an equalizing circuit operationally coupled to the amplifier. The equalizing circuit has a second gain response that compensates for the first gain response of the amplifier so that a substantially constant net gain is imparted by the amplifier and the equalizing circuit to the electrical signal over the first bandwidth.

An automatic gain control (AGC) circuit including a high gain amplifier, a feedback network and two transconductance amplifiers. The feedback network has a first end that receives an input signal of the AGC circuit, a second end coupled to the output of the high gain amplifier and two intermediate nodes. Each transconductance amplifier has an input coupled to a respective intermediate node of the feedback network and an output coupled to the input of the high gain amplifier. The transconductance amplifiers collectively control a position of a virtual ground within the feedback network to control gain of the AGC circuit. The transconductance amplifiers each include an attenuator and a transconductance stage coupled between the feedback network and the high gain amplifier and are configured to operate linearly across a relatively wide input voltage range. The input offset voltage of the AGC circuit varies monotonically with gain of the AGC circuit.

Systems and methods that utilize a received signal to provide low cost, low power, high sensitivity radio frequency hopping communication. A transmitting system prepares a data packet that is to be communicated to a receiving system. The data packet includes a header, a network identification, and transmission data. A transmission frequency is identified and a phase lock loop (“PLL”) is set to the transmission frequency. The data packet is gathered, and frequency modulation and Differential Manchester encoding is performed. The signal is sent through a power amplifier and an antenna to a receiving system, which continually scans all channels of a frequency range for a valid signal. When a pulse is received, the signal is passed through a low noise amplifier, mixed down to 10.7 MHz, passed through one or more filters and one or more high gain amplifiers, mixed down to baseband, sent through a low pass filter, and then sent through a comparator. If an appropriate pulse width, expected bit pattern and a valid header are received, it is determined that the signal is valid and the entire data packet is demodulated to receive the transmitted data.

A traveling wave device employs an active Gallium Nitride FET. The Gallium Nitride FET has a plurality of gate feeding fingers connecting to an input gate transmission line. The FET has a drain electrode connected to an output drain transmission line with the source electrode connected to a point of reference potential. The input and output transmission lines are terminated with terminating impedances which are not matched to the gate and drain transmission lines. The use of Gallium Nitride enables the terminating impedance to be at much higher levels than in the prior art. The use of Gallium Nitride permits multiple devices to be employed, thus resulting in higher gain amplifiers with higher voltage operation and higher frequency operation. A cascode traveling wave amplifier employing GaN FETs is also described having high gain and bandwidth.

A crystal amplifier for driving a crystal to oscillate at a resonant frequency including a controlled current source, a primary amplifier core, a high gain amplifier core, and a controller. Both amplifier cores are coupled in parallel, and each has an input coupled to an amplifier input node and an output coupled to an amplifier output node coupled across the crystal. The current source provides a core bias current to the source node. The controller enables the high gain amplifier core and sets the core bias current to a high current level to achieve a high negative resistance at a startup time, and then disables the high gain amplifier core and sets the core bias current to a lower steady state current level after oscillation is achieved. A level detector may be used for detecting oscillation and for determining when to adjust the core bias current.

A high gain optical amplifier and method. Generally, the inventive amplifier includes a first crystal having an axis and a first index of refraction and a second crystal bonded to the first crystal about the axis and having a second index of refraction. The first index is higher than the second index such that light through the first crystal is totally internally reflected. In the illustrative embodiment, the first crystal is Yb:YAG with an index of approximately 1.82, the second crystal is Sapphire with an index of approximately 1.78, and the axis is the propagation axis. The invention is, in its preferred embodiment, a light guide fabricated out of crystalline materials, diffusion bonded together. If the core of the light guide is doped with laser ions, high gain amplifiers made be designed and operable over a large étendue. With a judicious choice of the laser crystal and cladding materials, shape, and bonding technique, the guided amplifier is much less susceptible to parasitic oscillation than amplifiers constructed in accordance with conventional teachings. The clad core is also able to handle larger thermal load without breakage than can an unclad core.

An active gate control circuit provided with the invention comprises a voltage feedback control circuit unit, an active voltage clamping circuit unit, a high-speed and high-gain amplifier and a gate driving power amplifier unit. The method comprises signal input, IGBT (Insulated Gate Bipolar Transistor) closure, AGC (Active Gate Control) action and hybrid interference measurement and analysis. The IGBT electromagnetic interference inhibition method thereof is simple in circuit structure, easy to realize, high in work efficiency and stability, low in switching loss and high in accurate degree, can inhibit the electromagnetic interference and has the universality for the power semiconductor device controlled by a switch.

The invention relates to a high gain amplifier circuit which is formed by a cascade transistors structure. The grids of the cascade transistors are connected together and the source drains are orderly connected serially. Each cascade transistor is in an amplifying state and has high output impedance and high gain. The amplifier circuit is characterized by high gain, wide input swing range and simple grid polarization. The invention is fit for the application places requiring high gain, big swing and low power consumption.

In one embodiment, the present invention provides an amplifier circuit including a cascode input stage coupled to a differential stage. In another embodiment, an amplifier includes a differential stage coupled to a common gate stage. Embodiments of the present invention also include an improved low voltage amplifier using a 3-stage topology including a wide-swing folded-cascode input stage followed by a differential gain stage which provides improved gain and output compliance. Embodiments of the present invention improve the available cascode stage headroom and reject process and temperature induced parametric variations.

A multiple-stage operational amplifier including a gain stage for amplifying an input signal and implementing a dominant pole producing a frequency response having a gain roll-off with frequency and a unity gain frequency. An intermediate stage is coupled to an output of the gain stage and has a high input impedance and a low output impedance. A high gain amplifier configured as a low gain output stage using resistive feedback and coupled to an output of the intermediate stage drives an output of the operational amplifier and implements a dominant pole at a frequency substantially higher than the unity gain frequency implemented by the dominant pole implemented the gain stage.

A low drop out, LDO, voltage regulator circuit is that includes a high gain amplifier configured to receive a current biasing signal and arranged to regulate the voltage supply signal and output a regulated voltage supply signal. A regulation adjustment circuit is operably coupled to an output of the high gain amplifier and includes a comparator configured to compare the output regulated voltage supply signal with a threshold, wherein an output of the comparator is configured to perform one of: (i) supply a dynamic current boost to the LDO current biasing signal, in response to the regulated voltage supply signal voltage dropping below the threshold; (ii) activate a dynamic current pull down circuit to reduce an over voltage output of the LDO voltage regulator circuit in response to the regulated voltage supply signal voltage exceeding the threshold.

A flexible wireless network system adapted for switching to a desired frequency and efficiently amplifying signal strength of an input RF signal of the desired frequency in wireless communications while meeting ACLR requirements. The system includes an input source to receive the input RF signal, a input filter bank RF amplifier, a pre-distortion engine, a high gain amplifier connected to the pre-distortion engine, a filter module, a low gain amplifier connected to the filter module, an output antenna connected to the low gain amplifier, a computer to control switching in the input filter bank and the filter module so that the correct filters are used with the input RF signal. The input filter bank and FM Filter banks include a filter capable of switching between a multiple of frequencies so that the frequency of the input RF signal can be selected and received into the system from the input source.

An RF transmitter with improved efficiency and good linearity decomposes an input AM signal into two signal envelopes with phased modulation at a phase angle θ. The transmitter has three principal embodiments. A first solution uses at least one added RF amplifier for each decomposed signal envelope with one or more amplifiers having a low gain compared to that of a high gain amplifier in another branch for the same signal envelope. A phase angle θi is determined that corresponds to a switching on two of the 2n+2 total branches, n=0, 1, 2, . . . . A second solution uses the same general schematic architecture as the classic LINC system that requires only two RF amplifiers, but uses a different decomposition because the two RF amplifiers are used in their nonlinear zone. The decomposed signal envelopes can be variable. The amplified output signal allows the combiner to be used at 100% efficiency in major part of signal. The third solution combines the first and second solutions.

A high gain optical amplifier and method. Generally, the inventive amplifier includes a first crystal having an axis and a first index of refraction and a second crystal bonded to the first crystal about the axis and having a second index of refraction. The first index is higher than the second index such that light through the first crystal is totally internally reflected. In the illustrative embodiment, the first crystal is Yb: YAG with an index of approximately 1.82, the second crystal is Sapphire with an index of approximately 1.78, and the axis is the propagation axis. The invention is, in its preferred embodiment, a light guide fabricated out of crystalline materials, diffusion bonded together. If the core of the light guide is doped with laser ions, high gain amplifiers made be designed and operable over a large étendue. With a judicious choice of the laser crystal and cladding materials, shape, and bonding technique, the guided amplifier is much less susceptible to parasitic oscillation than amplifiers constructed in accordance with conventional teachings. The clad core is also able to handle larger thermal load without breakage than can an unclad core.

A D.C. offset canceling technique and a gain adjusting technique permitting completion of correction of D.C. offsets and gain adjustment of amplifiers for amplifying reception signals in a relatively short period of time in a radio communication system, such as a wireless LAN, are to be provided. A communication semiconductor integrated circuit (high frequency IC) has a plurality each of low-pass filters and variable gain amplifiers which are alternately connected in multiple stages, and high gain amplifier circuits for amplifying reception signals to a predetermined amplitude level while eliminating unnecessary waves. Offset cancellation values are generated by detecting in advance D.C. offsets of amplifiers for amplifying reception signals according to a set gain, and stored into a memory, and read out of the memory to cancel the D.C. offsets of the amplifiers at the time of starting reception and altering the gain. Gain setting in a high gain amplifying section for amplifying reception signals is accomplished in two steps, rough setting and precise setting.

A multi-mode optical fibre gang is prepared from multi-mode optical fibres through close arranging, fixing, and grinding and polishing its one end to form a light-receiving surface by an angle relative to optical axis. It is optically connected with a double-cladded optical fibre. A prism waveguide coupling method is also disclosed. The light is pumped to the incident surface of prism waveguide and then coupled into said double-cladded optical fibre and in turn to said optical fibre gang.

An amplification system including a high gain amplifier, filter module and low gain amplifier. The high gain amplifier for receiving an input RF signal and processing the input RF signal to produce a first amplified signal while the high gain amplifier is operating near its saturation point. The filter module having at least one band pass filter to receive the first amplified signal and process the first amplified signal to remove unwanted characteristics of the first amplified signal to produce a processed first amplified signal. The low gain amplifier receiving the processed first amplified signal and processing the processed first amplified signal to produce a second amplified signal that has an increase in signal strength over the processed first amplified signal while the low gain amplifier is operating near its saturation point.

A rail-rail comparator having an input stage with independent positive and negative differential voltage offset compensation tracks changes in Gm (transconductance) of the input stage. By tracking the changes in Gm (transconductance) of the input stage, hysteresis of the rail-rail comparator becomes insensitive to the input common mode voltage. A two-stage rail-rail comparator may be used for adding hysteresis to a second stage. The first stage of the two-stage rail-rail comparator operates at substantially unity gain. The second stage of the two-stage rail-rail comparator operates as a regular high gain amplifier with hysteresis. Additional circuitry tracks the Gm (transconductance) change of the first stage to make the second stage hysteresis insensitive to the input common mode voltage at the first stage.; This also makes it easier to create a programmable hysteresis that is accurate over all input voltage values.