摘要:
An input system for a variable gain amplifier using a continuously interpolated attenuator includes a plurality of gm stages in which the collector current from one transistor in each gm stage is diverted to AC ground, thereby eliminating a feedforward path and providing flat frequency response at very high frequencies. An additional feedforward path through the parasitic emitter capacitances in each gm stage is eliminated by a filter capacitor coupled the common emitter node of each gm stage. A compensation transistor included in each gm stage provides a differential output signal which can be used to cancel common mode feedforward signals which are coupled to the output through the collector-junction capacitances of the gm stages. The effects of parasitic capacitances are further reduced by reverse biasing the gm stages that are off.
摘要:
An RMS-DC converter generates a series of progressively amplified signal pairs which are then multiplied and weighted in such a way as to cancel uncorrelated noise while still providing true square-law response. The converter includes two series of gain stages for generating the amplified signal pairs, and a series of four-quadrant multipliers for multiplying and weighting the amplified signal pairs in response to a series of weighting signals. The outputs from the multipliers are summed and averaged, and a final output signal is generated by integrating the difference between the averaged signal and a reference signal. To preserve the square-law response over a wide range of input voltages, the system is servoed by feeding the final output signal back to an interpolator which generates the weighting signals as a series of continuously interpolated, overlapping, Gaussian-shaped current pulses having a centroid that moves along the length of the interpolator as the final output signal varies. An embodiment can also be implemented with a single series of gain stages that generate a series of amplified signals which are squared, weighted, and averaged.
摘要:
A current control circuit is provided which is capable of maintaining a constant DC current flowing in a load resistor irrespective of the resistance value of a load resistor connected to a connection terminal. To this end, a constant current circuit (21) is connected to a RING terminal (2), which acts as the connection terminal. The constant current circuit (21) controls a current drive circuit (6) in response to a voltage at the RING terminal (2) to ensure that a DC current flowing in a power feed resistor (4) is kept constant. Due to the fact that DC current flowing in the load resistor irrespective of the resistance value of the load resistor is kept constant, the burden placed on a power supply of a subscriber line interface in a telecommunications network is no longer increased. Also, there no longer arises a need for increasing a power feed resistance and the rating of a power feed transistor, which, in turn, leads to a reduction in manufacturing cost.
摘要:
A match-insensitive low current bias circuit uses a transistor arrangement which takes advantage of the transistors' collector current degeneration, current gain through emitter sizing, and voltage gain to minimize any errors caused by stage mismatches created during production. The bias circuit of the present invention is particularly suited to integrated circuit applications where a low biasing current is required.
摘要:
A switching regulator includes an oscillation circuit for generating a triangular waveform signal having a predetermined frequency, a comparator compares the triangular waveform signal generated by the oscillation circuit with a voltage control signal commensurate with a voltage to be output so as to generate a pulse signal which goes high or low depending on a result of the comparison, and a driving circuit for selecting a portion of the triangular waveform signal generated by the oscillation responsive to the pulse signal generated by the comparator, so as to generate the drive signal for driving the switching element.
摘要:
A constant-current generating circuit, a power-source voltage being applied thereto, generates a constant current. A voltage generating circuit element is connected between the constant-current generating circuit and a fixed voltage point, is supplied with the constant current which is generated by the constant-current generating circuit, and generates a constant voltage. A control circuit detects the current generated by the constant-current generating circuit, and, using the detected current, controls the constant-current generating circuit so that the current to be supplied to the voltage generating circuit element is the constant current.
摘要:
A circuit arrangement (16) for producing a D.C. current, includes a feedback loop for producing a reference current from an output terminal (27) with a negative temperature coefficient. The feedback loop includes a current-source stage (17, 18) which feeds a current mirror stage (19, 20, 21) in response to a measuring current supplied from a current bank (24, 25, 28, 29), which also produces the output reference current. The output of the current mirror stage (19, 20, 21) drives a working impedance formed by the main current path of a transistor 22, across which a control voltage is developed which is applied to a control input (23) of the current bank (24, 25, 28, 29). The circuit arrangement is advantageously combined with a reference current source (1) arranged as a bandgap circuit for producing a reference current on an output terminal (2) with a positive temperature coefficient, by enabling the user to select a current reference with either a positive or negative temperature coefficient. Further, the respective reference current outputs with positive and negative temperature coefficients, properly dimensioned, may be combined to provide an output current from a common output terminal (35) which is independent of temperature in a predefined temperature range.
摘要:
A power supply unit has a transistor and a resistor circuit connected in series between a power source line and a reference potential point. The node between the transistor and the resistor circuit is connected to an output terminal. A capacitor is connected between the output terminal and the reference potential point. In response to the activation of a starting switch, the transistor is turned on. The power supply unit further has a delay circuit for delaying a rise in the voltage at a predetermined point in the resistor circuit, a current limiting circuit for limiting the current flowing through the transistor, and a current limiting level control circuit for controlling, in accordance with the output of the delay circuit, the level to which the current limiting circuit limits the current. Thus, output of an unduly large current is suppressed when the power supply unit is started up in response to the activation of the starting switch.
摘要:
The present invention relates to a constant voltage control device for preventing parasitic transistors from operating, which comprises a constant voltage generating section, an undervoltage lock-out section, an operation control section, and a supply voltage control section. According to the present invention, parasitic transistors induced during the operation of a switching transistor made of a lateral transistor are prevented from operating by feedback of a signal derived from the Vref signal output from the constant voltage generating section to the operation control section. Unwanted power consumption by the parasitic transistors is reduced and malfunction resulting therefrom is prevented.
摘要:
The present invention relates to an apparatus and method for voltage regulation. The apparatus includes an error amplifier circuit in communication with an external reference voltage input. The error amplifier circuit produces an error voltage that is proportional to the difference between an external reference input voltage and an output voltage. A series pass circuit is in communication with the error amplifier circuit and is responsive to the error voltage. The method comprises the steps of comparing an external reference voltage to an output voltage, generating an error voltage proportional to the difference between the external reference voltage and the output voltage, and regulating the output voltage based upon the error voltage.