392 results about "Operational transconductance amplifier" patented technology

In low-voltage circuits, there is often insufficient voltage to use a current source to bias a transconductance amplifier stage. This is particularly true in mixers where a switching circuit must be stacked on top of the transconductance input stage. One way around this problem is to get "double-duty" out of the input differential pair, using it both for gain stage and for DC bias. This is done by AC coupling in a high-frequency input signal, while using a low-frequency, DC-coupled circuit to establish the proper bias level. One common technique is to use a simple current mirror scheme to establish the DC level. Proper biasing using this technique requires good matching of resistance. In some implementations of transconductance amplifiers, particularly those that use inductors as degeneration elements, series resistance of the inductor and interconnect resistance can cause significant errors in the bias current. This invention addresses that problem by using an operational amplifier with a current-sensing resistor and a low-frequency feedback loop to compensate automatically for any resistance errors. The operational amplifier drives the feedback voltage (generated in accordance with the sensed voltage at the current-sensing resistor and applied to one input of the operational amplifier) towards a reference voltage that is applied to the other input of the operational amplifier to bias the transistor(s) in the transconductance amplifier for desired operating conditions.

According to one embodiment of the invention, a circuit comprising a plurality of operational transconductance amplifiers (OTAS) is described. The first OTA has differential input and differential output. The second OTA also has differential input, where a first output of the first OTA is coupled to the first differential input of the second OTA, which is an inverting input. A second output of the first OTA is coupled to the second input of the second OTA, which is a non-inverting input. The first differential output being coupled to a first input of the first OTA and the second differential output being coupled to a second input of the first OTA for negative feedback and current biasing.

A buck switching regulator includes a feedback control circuit including a first gain circuit generating a first feedback signal indicative of the regulated output voltage; a ripple generation circuit generating a ripple signal that is injected to the first feedback signal; and a comparator receiving a first reference signal and the first feedback signal to generate a comparator output signal. The switching regulator further includes an offset compensation circuit including a second gain circuit generating a second feedback signal indicative of the regulated output voltage; and an operational transconductance amplifier (OTA) configured to receive the second feedback signal and the first reference signal and to generate an output signal. The output signal of the OTA is coupled to the comparator to adjust an offset to the comparator so as to cancel the offset at the regulated output voltage due to the injected ripple signal.

Circuits and methods to achieve dynamic biasing for the complete loop transfer function of a current mode voltage regulator have been achieved. The circuit comprises a Mirror-Transconductor Amplifier type operational transconductance amplifier (OTA) wherein its transconductance is linearly dependent on its biasing current. This biasing current is a linearly derivative of the OTA's output current. A current amplification circuit couples the regulator output current linearly with said OTA's output current. In this configuration the iterative biasing of the OTA forms a feed-forward loop, which contains a low-pass filter for stability and a negative feedback loop is closed by connecting the regulator voltage output to the OTA input. The invention realizes a purely current mode regulator since all internal currents are generated as a fraction of the output load.

A chopper-stabilized amplifier receiving an input signal includes a first operational transconductance amplifier having an input chopper and an output chopper for chopping an output signal produced by the first operational transconductance amplifier. A switched capacitor notch filter filters the chopped output signal by operating synchronously with the chopping frequency of output chopper to filter ripple voltages that otherwise would be produced by the output chopper. In one embodiment, a second operational transconductance amplifier amplifies the notch filter output. The input signal is fed forward, summed with the output of the second operational transconductance amplifier, and applied to the input of a fourth operational transconductance amplifier. Ripple noise and offset are substantially reduced.

Disclosed are low power electronic devices configured to exploit the sub-threshold swing, unidirectional tunneling, and low-voltage operation of steep slope-tunnel tunnel field-effect transistors (TFET) to improve power-conversion efficiency and power-efficiency of electrical systems incorporating the TFET as an electrical component to perform energy harvesting, signal processing, and related operations. The devices include a HTFET-based rectifier having various topologies, a HTFET-based DC-DC charge pump converter, a HTFET-based amplifier having an amplifier circuit including a telescopic operational transconductance amplifier, and a HTFET-based SAR A/D converter having a HTFET-based transmission gate DFF. Any one of the devices may be used to generate a RF-powered system with improved power conversion efficiencies of power harvesters and power efficiencies of processing components within the system.

A bandgap reference system has a bandgap circuit, an operational transconductance amplifier, and an offset controller. The bandgap circuit includes a pair of diode devices and has a reference terminal at which is provided a bandgap reference voltage. The bandgap circuit provides a differential output having a first output and a second output. The operational transconductance amplifier has a first input coupled to the first output of the bandgap circuit, a second input coupled to the second output of the bandgap reference circuit, and an output coupled to the reference terminal. The offset controller is coupled to the operational transconductance amplifier and to the first and second outputs of the bandgap circuit. The offset controller trims the operational transconductance amplifier as needed to ensure an offset of the operational transconductance amplifier is below a predetermined level.

The invention belongs to the technical field of power sources and relates to a self-adaptation voltage regulator circuit. The self-adaptation voltage regulator circuit comprises a power tube MP, a power tube MN, an inductor L, a capacitor C, a first resistor RF1, a second resistor RF2, a simulation phase lead compensation module, a delay phase lag compensation module, a critical path duplication module, a sawtooth wave generating module, a comparator and a power tube driver. The output voltage Vout is partitioned by the first resistor RF1 and the second resistor RF2. Simulation phase lead compensation is achieved through an operational amplifier, the resistor R1, the resistor R2 and the capacitor C. A load of an operational transconductance amplifier GM is RGM1 and provides the loop gain of APD compensation. The delay of the duplication of the critical path is compared with a system clock CLK through phase detection. Then, delay error signals are integrated through a charge pump. The output voltage VPD of the charge pump is connected to the positive going input end of the operational transconductance amplifier GM. PWM waveforms can be obtained by comparing the sawtooth wave current generated by an oscillator OSC and the output current of the GM. By means of the self-adaptation voltage regulator circuit, the power loss of a digital circuit is greatly reduced.

An apparatus in an electronic device such as a buck converter circuit receives as a first input a voltage signal VSNS from the electronic device that represents a current through the electronic device, and receives as a second input a direct current reference voltage signal from a reference voltage source VREF. The apparatus regulates a direct current output IOUT of the electronic device with respect to the reference voltage source VREF by applying a pulse level transformation to the voltage signal VSNS using an operational transconductance amplifier.

A buck switching regulator includes a feedback control circuit including a first gain circuit configured to generate a first feedback signal indicative of the regulated output voltage; a ripple generation circuit configured to generate a ripple signal using the switching output voltage and to inject the ripple signal to the first feedback signal; a second gain circuit configured to generate a second feedback signal indicative of the regulated output voltage; an operational transconductance amplifier (OTA) configured to generate an output signal having a magnitude indicative the difference between the second feedback signal and the first reference signal; and a comparator configured to generate a comparator output signal having an output level indicative of the difference between the output signal of the OTA and the first feedback signal. As thus configured, the buck switching regulator generates an output voltage with increased accuracy and fast transient response.

A nested transimpedance amplifier (TIA) circuit comprises a zero-order TIA having an input and an output. A first transconductance amplifier has an input that communicates with said output of said zero-order TIA and an output. A first feedback resistance has one end that communicates with said input of said zero-order TIA and an opposite end that communicates with said output of said first transconductance amplifier. A first feedback capacitance has a first end that communicates with said input of said zero-order TIA and a second end that communicates with said output of said zero-order TIA. A capacitance has one end that communicates with said input of said zero-order TIA.

A DC-DC converter includes an error amplifier that includes an operational transconductance amplifier (OTA), a compensation circuit, and a fast transient controller. The OTA includes a compensation resistor, a compensation capacitor of C_z, and a Miller circuit. The equalization capacitance generated by the compensation capacitor and the Miller circuit is (1+k) C_z. The Miller circuit includes three transistors operated in the triode region. The ratio of the current through the transistors is 1:mk:(1−m)k. The current through the compensation capacitor in a second mode is (1+mk) times that in a first mode. The fast transient controller switches the Miller circuit between the first and second modes according to a feedback voltage dependent on the output voltage of the DC-DC converter.

Full-AC load flow constitutes a core computation in power system analysis. The present invention provides a performance gain with a hardware implementation of a sparse-linear solver using a Field Programmable Gate Array (FPGA). The invention also relates to the design, simulation, and hardware verification of a static transmission line model for analog power flow computation. Operational transconductance amplifiers are employed in the model based on a previously proposed DC emulation technique of power flow computation, and provide reconfigurability of transmission line parameters via transconductance gain. The invention also uses Analog Behavioral Models (ABMs) in an efficient strategy for designing analog emulation engines for large-scale power system computation. Results of PSpice simulations of these emulation circuits are compared with industrial grade numerical simulations for validation. The application is also concerned with the development of a generator model using analog circuits for load flow emulation for power system analysis to reduce computation time. The generator model includes reconfigurable parameters using operational transconductance amplifiers (OTAs). The circuit module is used with other reconfigurable circuits, i.e., transmission lines and loads.

A large-scale field-programmable analog array (FPAA) for rapidly prototyping analog systems and an arbitrary analog waveform generator. The large-scale FPAA includes a floating-gate transistor array and a plurality of computational analog blocks (CABs), which may be adapted to set bias voltages for operational transconductance amplifiers (OTAs), adjust corner frequencies on the capacitively coupled current conveyors, set multiplier coefficients in vector-matrix multipliers, and a variety of other operations. The floating-gate transistors may be used as switch elements, programmable resistor elements, precision current sources, and programmable transistors. Accordingly, the floating-gate transistors within the array allow on-chip programming of the characteristics of the computational elements, while still maintaining compact CABs. The arbitrary analog waveform generator may include programmable floating-gate MOS transistors for use as analog memory cells to store samples of the waveforms.

The invention discloses a gain increased operational transconductance amplifier which is formed in a manner that a bias constant current source is sequentially connected with differential input, a load current mirror, a cascode output stage and an adjustable auxiliary differential pair in sequence, wherein the differential input is composed of four PMOS pipes namely M1a, M2a, M1b and M2b; the load current mirror is composed of six NMOS pipes namely M3, M4, M5a, M6a, M5b and M6b; the cascode output stage is composed of six MOS pipes namely M7, M8, M9, M10, M11 and M12; the adjustable auxiliary differential pair is composed of M13, M14 and M15. Reutilization of current and the output stage increased adjustable auxiliary differential pair thoroughly solve the inherent contradiction among gain, bandwidth, power dissipation and the like in a circuit; the gain increased operational transconductance amplifier is slightly influenced by output voltage, an additional pole is not introduced, the simulation results show same static power dissipation, and multiplication is realized for gain and bandwidth; the gain increased operational transconductance amplifier further has the characteristics of fine tuning and high accuracy and is applicable to communication, electronic measurement and automatic control systems.

A buck switching regulator includes a feedback control circuit including a feedback network including first and second gain circuits configured to generate first and second feedback signals, respectively, indicative of the regulated output voltage; a ripple generation circuit configured to inject a ripple signal to the first gain circuit; an operational transconductance amplifier (OTA) configured to receive the second feedback signal and a reference signal and to generate an output signal being coupled to the first gain circuit to adjust the first feedback signal; and a comparator configured to receive the first feedback signal and the reference signal and to generate a comparator output signal. The output signal of the OTA is applied to the first feedback signal to cancel a voltage offset in the regulated output voltage due to the injected ripple signal to the first gain circuit.