摘要:
A programmable-gain multistage amplifier with broad bandwidth and reduced phase variations having a differential input stage biased by a first current source and to which a differential voltage signal is fed, the stage being connected to a pair of diodes in which the cathode terminals are connected to respective bipolar transistors, which are biased by a second current source and in which the collector terminals are connected to load resistors, the differential output of the amplifier being provided at the collector terminals of the bipolar transistors. The amplifier further includes two circuit branches, each of which is constituted by a bipolar transistor and by a third current source, which is respectively connected to the collector terminal and emitter terminal of the bipolar transistor, in which the base terminal receives the differential voltage signal and the collector terminal is connected to the cathode terminal of a respective one of the two diodes, the circuit branches being mutually connected by means of a pair of capacitors.
摘要:
An amplifier with programmable gain and input linearity at high frequency allows an increase in the gain without effecting input linearity and without significantly increasing current consumption. The amplifier includes an input stage which receives a voltage signal for performing a current conversion thereof with compression. An output stage is connected to the input stage and decompresses the signal provided by the input stage for producing gain amplification thereof. The amplifier further includes at least one current amplifier stage interposed between the input stage and the output stage. The at least one current amplifier includes at least one bipolar transistor series-connected to a load diode and to a current source. A reduction in the transconductance of the load diode is provided in the at least one amplifier stage to determine a programmable gain factor for the amplifier.
摘要:
This invention relates to a circuit structure of the feedforward type with programmable zeroes, particularly for synthesizing time-continual filters. This structure comprises a pair of amplification cells interconnected at least one interconnection node and connected between a first signal input of a first cell and an output terminal of the second cell, each cell comprising a pair of transistors which have a conduction terminal in common and have the other conduction terminals coupled respectively to a first voltage reference through respective bias members. The structure further comprises a circuit leg connecting a node of the first cell to the output terminal and comprising a transistor which has a control terminal connected to the node of the first cell, a first conduction terminal connected to the output terminal, and a second conduction terminal coupled to a second voltage reference through a capacitor. Thus, a released “zero” can be introduced in the right semiplane of the pole-zero complex plane to improve the flattening of group gain.
摘要:
A device generates pulses of high-precision with programmable duration. The device includes first, second and third pulse generator circuits. The first pulse generator circuit receives at an input a pulse generation command signal, and provides at an output a first pulse for loading the contents of a register in a counter. The second pulse generator circuit is triggered by the first pulse provided by the first pulse generator circuit. The third pulse generator circuit is triggered by a second pulse provided by the second pulse generator circuit, and generates a third pulse to restart the second pulse generator circuit. The second pulse provided by the second pulse generator circuit forms a clock signal for the counter to produce a decrement in the counter. The output signal from the counter is the pulsed signal to be generated. The duration of the pulsed signal is determined by the content of the counter.
摘要:
A feedforward circuit structure with programmable zeros for synthesizing continuous-time filters, delay lines, and the like is described. The circuit comprises a first cell and a second cell which are cascade-connected. Each one of the first and second cells comprises first and second pairs of bipolar transistors. The emitter terminals of the first pair of transistors are connected to a first current source, and the emitter terminals of the second pair of transistors are connected to a second current source. A first high-impedance element is connected between the first and second pairs of transistors, and a second high-impedance element is connected at an output of the second pair of transistors. A fifth transistor is connected between the collector terminal of a first transistor of the first pair of transistors and the collector terminal of a second transistor of the second pair of transistors. The base terminal of the fifth transistor receives a signal which is taken from the collector terminal of the first transistor of the first pair of transistors, with the signal being taken with a positive sign in the first cell and with a negative sign in the second cell, in order to determine a transfer function with a pair of singularities at the numerator. The second transistors of the first and second pairs of transistors are controlled respectively by third and fourth current sources which have mutually different values.
摘要:
An elementary cell structure for programmable time-continuous analog filters and in particular for the processing of analog signals in read/write operations on magnetic supports comprises an amplifier stage provided with a pair of structurally identical transconductance half-cells connected together in a common circuit node. With a cascade of cells of this type is provided a time-continuous analog delay line which is used in a transverse time-continuous analog filter. This filter comprises a cascade of identical delay lines connected through multiplier nodes to a final summation node. “Elementary cell structure for programmable time-continuous analog filters and in particular for read/write operations on magnetic supports and associated analog filter”
摘要:
A controlled gain transconductor (20) which comprises a transconductance stage (3) having at least two input terminals (I1, I2) and at least two output terminals (O1, O2), an active load (4) connected to the output terminals of the transconductance stage and a control circuit (5) for the active load (4) connected between said output terminals (O1, O2) and the active load (4).Also provided is a circuit portion (10) being a replica of the transconductance stage (3), the active load (4) and the control circuit (5). This replicated portion (10) has an output connected to the control circuit (5) of the transconductor (20) to provide a predetermined voltage value (Vc) required for adjusting the DC gain of the device.
摘要:
The invention relates to a low supply voltage analog multiplier which comprises a pair of differential cells, each cell comprising a pair of bipolar transistors with coupled emitters. A first transistor of each cell receives an input signal on its base terminal and has its collector terminal coupled to a first voltage reference through a bias member. Advantageously, the second transistor of each cell is a diode configuration, and the cells are interconnected at a common node corresponding to the base terminals of the second transistors in each pair. This multiplier can be supplied very low voltages and still exhibit a high rate of operation along with reduced harmonic distortion of the output signal, even with input signals of peak-to-peak amplitude above 600 mV.
摘要:
The system includes various circuit units each having a capacitor and a charging circuit for defining a quantity depending upon the ratio (I/C) between the charging current and the capacitance of the capacitors. In order to compensate automatically for deviations of the actual capacitances from the nominal capacitances due to fluctuations in the parameters of the integrated-circuit manufacturing process, the system has a phase-locked loop which uses one of the circuit units as an adjustable oscillator, and current transducer means which regulates the charging currents of the capacitors of the circuit units in dependence on the regulated charging current of the capacitor of the oscillator, or the error current of the PLL loop.
摘要:
The device is to be used with a parallel architecture partial response maximum likelihood (PRML) reading apparatus comprising a variable-gain input amplifier, a low-pass analog filter, a transversal continuous-time analog filter and two distinct and parallel processing channels interposed between the transversal analog filter and an RLL-NRZ decoder. The two processing channels comprise respective analog-digital converters and respective Viterbi detectors and operate according to sampling sequences that alternate with one another. The device for processing the servo signals comprises a rectifier connected to the outputs of the analog-digital converters and an integrator.