摘要:
There is disclosed an impedance conversion circuit called a regulated cascode circuit in which a parasitic capacity deteriorating frequency characteristics is reduced during operation up to about several hundreds of megahertz or higher frequencies. In the impedance conversion circuit comprising two regulated cascode circuits in which active elements and reverse amplifiers are interconnected with a feedback applied thereto, a capacity element is disposed between a control end of one active element and an output end of the other active element.
摘要:
A receiver having a function of a direct current offset, and including a receiving section for receiving a radio frequency signal, an analog signal processing section for amplifying, band-converting and frequency-converting an analog signal inputted from the receiving section, and an AD converting section for converting an output of the analog signal processing section from an analog signal to a digital signal. Also included is a digital signal processing section for processing the digital signal converted by the DC converting section. The receiver further includes an offset detecting element, provided in the digital signal processing section, for detecting a direct current offset signal produced in the receiving section or a frequency converting section, an offset holding element, provided in the digital signal processing section, for holding the direct current offset signal detected by the offset detecting element, a DA converting section for converting the direct current offset signal detected by the digital signal processing section into an analog signal, and a first offset correcting element, provided in the analog signal processing section, for correcting the analog signal on the basis of the direct current offset signal converted by the DA converting section into the analog signal.
摘要:
In an FDNR type active filter fabricated on an integrated circuit, an FDNR circuit is provided wherein one ends of a first capacitor and an impedance element are connected to an inverted input of an operational amplifier, one ends of the impedance element and a second capacitor are connected to an output end of the operational amplifier, and the other ends of the first and second capacitors are connected to each other. To the impedance element, resistors are connected in series. To the connecting end of the resistors, one end of another resistor is connected, the other end thereof being grounded in an alternating current form. The capacity value of the second capacitor is greater than that of the first capacitor.
摘要:
A frequency converter including a mixer circuit which inputs a local oscillation signal and a radio-frequency input signal modulated for communication of information, and performs frequency conversion. A buffer amplifier is higher than a desired signal frequency band, and has a low-pass passage characteristic of cut-off frequency lower than an adjacent channel carrier frequency.
摘要:
A balanced amplifier includes first and second multi-input single-ended output differential amplifiers having matched characteristics and a feedback circuit. The feedback circuit connects differential input terminals and output terminals of the first and second multi-input single-ended output differential amplifiers so that all of the differential input terminals of the first and second multi-input single-ended output differential amplifiers are virtually shorted.
摘要:
A frequency converter includes: a signal synthesizer element for inputting first and second input signals to synthesize these signals and for outputting a synthesized signal, from which noises even times as large as the frequency of the second input signal are removed; an amplitude limitation amplifier element, composed of a differential amplifier circuit, for amplifying the synthesized signal outputted from the signal synthesizer element to output an amplified signal having a constant amplitude; and a filter for inputting the amplified signal outputted from the amplitude limitation amplifier element, to remove an unnecessary signal component to produce an output a baseband signal including only a desired signal component. In addition, a radio receiver using the frequency converter of such a construction is designed to input the output of a local oscillator to a variable attenuator or a variable gain amplifier, to input the output of the variable attenuator or the variable gain amplifier as the first input signal to the frequency converter so as to perform the gain control. Thus, not only is self-mixing, a common problem in direct conversion receivers, prevented, but also, because a smaller local oscillation driving signal is required, power consumption is significantly reduced.
摘要:
An amplifier device capable of performing an efficient amplifying operation with a low power consumption includes an amplifier circuit at least having an input amplifier stage which amplifies a level change of an input signal to output an amplified current, and an output stage which outputs the amplified current as a driving output to a capacitive load; a primary bias circuit for ordinarily supplying a constant and main bias current to the amplifier circuit; a determination element for determining a change condition of the level change of the input signal, which is supplied from the input amplifier stage, so as to generate a control signal corresponding to said change condition; and a driving capability increase element as a secondary bias circuit for increasing a bias current in order to increase the driving output supplied to the capacitive load when the control signal is input.
摘要:
An amplifier device includes: a current amplifier element for amplifying an output current delivered to a capacitive load, such as, for example, a liquid crystal panel in dependency upon changes of the voltage of an input signal; an element for determining the state of changes in the input signal; and a control element for controlling the current amplifier element depending upon the state of changes in the input signal determined by the determination element in order to improve the output driving capability for the load. This amplifier device is applicable to an amplifier in a narrow sense and a buffer circuit in accordance with the mode of amplification. The former may include the configuration in which a second bias circuit for adding a bias current when the driving capability is required to be enhanced is provided in addition to an elementary bias circuit, and the configuration in which a first output drive element and the second output drive element and a plurality of output drive elements succeeding thereto are provided for additionally carrying out switching between incremental output currents. The latter may be classified into two types depending upon whether or not the potential difference element provided on the output side of the buffer circuit to detect a potential difference between the input and the output to add the output current when the the potential difference thus detected is above the threshold level.
摘要:
A variable gain amplifier comprises a main amplifier circuit whose gain is controllable and which amplifies a difference signal between an input signal and a feedback signal, a feedback amplifier circuit whose gain is controllable and which amplifies an output signal of the main amplifier circuit, and a gain control circuit which complementarily control the gain of the main amplifier circuit and the gain of the feedback amplifier circuit.
摘要:
A variable gain amplifier device comprises a variable gain amplifier circuit which amplifies a difference between an input signal and a feedback signal to output an output signal, a feedback circuit which supplies the feedback signal to the variable gain amplifier circuit, and a controller which controls the variable gain amplifier circuit and the feedback circuit to decrease a cutoff frequency of the feedback circuit according to increase of a gain of the variable gain amplifier circuit or vice versa.