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Operational Amplifiers
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
Aside from the active bias circuitry on the output branch of the circuit, the bulk of the voltage protection circuitry consists of additional cascode devices. Since the output swing of this stage is rail-to-rail, cascode devices are required to protect the output drivers, M37 and M40, from excessive VDS. Regulated ohmic cascodes are used to control the VDS levels in the output driver branch [27]. This structure regulates the gate bias of the cascode devices by comparing the VDS of the output devices to a mid-supply voltage. As the VDS across M37 and M40 varies with output voltage, the regulation amplifiers adjust the gate bias of the ohmic cascode transistors to maintain the voltage level and prevent a SOA violation. Additional clamping devices, marked on the schematic at CL1 and CL2, are used to limit the VGS of M38 and VSG of M39. Frequency compensation for the amplifier is provided by a relatively standard compensation network comprised of Miller capacitors and active resistors to optimize the op amp’s pole-zero constellation.
CMOS Amplifiers
Published in Tertulien Ndjountche, CMOS Analog Integrated Circuits, 2017
The two-stage amplifiers of Figures 5.56 and Figures 5.57 consist of a differential input stage, an inverting output stage, and a biasing circuit. The single-ended signal is provided by the current mirror used as load of the transistor differential pair and the amplifier output swing is Vsup−2VDS(sat), where Vsup denotes the supply voltage. The Miller frequency compensation with a pole-zero cancelation is adopted to overcome the gain-bandwidth trade-off. A one-pole frequency response of the amplifier is obtained by including a zero in the left-half plane of the s-domain to cancel the first nondominant pole. The compensation section [35,40,43] can be implemented using a resistor in series with a capacitor, as shown in Figure 5.56, or a series connection of a MOS transistor operating in the triode region and a capacitor, as illustrated in Figure 5.57 [35].
F
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
free-page list free-page list a linked-list of information records pointing to "holes" (i.e., free page frames) in main memory. free-space interconnect interconnect using optical elements such as lenses, gratings, and holograms, in which optical signals may cross each other in the space. The main advantages are high interconnection density and parallelism, and dynamic reconfiguration. free-wheeling diode a diode connected in parallel with the load of a half-wave rectifier to prevent the return of energy from the load to the source. Due to the stored energy in the inductive load, the current must continue after the source voltage becomes negative. The freewheeling diode provides a path for the current to circulate and allows the diode or SCR in the rectifier to turn off. Fremdhold integral equation a linear integral equation wherein the limits of integration are fixed. frequency the repetition rate of a periodic signal used to represent or process a communication signal. Frequency is expressed in units of hertz (Hz). 1 Hz represents one cycle per second, 1 MHz represents one million cycles per second, and 1 GHz represents one billion cycles per second. frequency chirp a monotonic change in optical frequency with time; often used for laser radar ranging in analogy with conventional radar and for ultrashort pulse generation via pulse compression or autocorrelation. See also chirp signal. frequency compensation the modification of the amplitude-frequency response of an amplifier to broaden the bandwidth or to make the response more nearly uniform over the existing bandwidth. frequency converter an equipment or circuit that converts an RF signal to an intermediate (IF) signal in receivers. It converts an IF signal to an RF signal in transmitters. frequency correlation function a function characterizing the similarity of a received signal with respect to a shift in frequency. frequency deviation in a frequency modulated system, the number of hertz the carrier is varied during the modulation process. frequency distortion caused by the presence of energy storage elements in an amplifier circuit. Different frequency components have different amplifications, resulting in frequency distortion, and the distortion is specified by a frequency response curve. frequency division duplex (FDD) a technique based on the allocation of two separate frequency bands for the transmission in both directions in a link. FDD typically requires a guard band between the two frequency bands in order to eliminate interference between the transmitter and receiver at a terminal. In a full duplex communication system, information flows simultaneously in both directions between two points. frequency division multiple access (FDMA) a multiple-access technique based on assigning each user a unique frequency band upon which transmission takes place. See also time division multiple access, code division multiple access. frequency division multiplexing (FDM) refers to the multiplexing of signals by shifting each signal to a different frequency band. See also frequency division multiple access. frequency domain representation of a signal by frequency components, such as its Fourier transform. frequency domain sampling a procedure that is a dual of the time-domain sampling theorem,
A novel current controller in photovoltaic grid-connected inverter
Published in Journal of the Chinese Institute of Engineers, 2021
Peng Mao, Mao Zhang, Yaru Zhu, Weiping Zhang
Proportional Resonant (PR) control is based on the application of Generalized Integrator (GI). A double integrator achieves infinite gain at a certain frequency, called resonance frequency, and almost no attenuation outside this frequency. It will lead to zero stationary error and selective disturbance rejection as compared with PI controller. Besides, single frequency compensation (obtained with the generalized integrator tuned at the grid frequency) and selective harmonic compensation can be also achieved by cascading several resonant blocks tuned to resonate at the desired low-order harmonic frequencies.