Abstract: Techniques for designing a low-noise amplifier (LNA) for operation over a wide range of input power levels. In an exemplary embodiment, a first gain path is provided in parallel with a second gain path. The first gain path includes a differential cascode amplifier with inductor source degeneration. The second gain path includes a differential cascode amplifier without inductor source degeneration. The cascode transistors of the gain paths may be selectively biased to enable or disable the first and/or second gain path. By selectively biasing the cascode transistors and input transistors, various combinations of the first and second gain paths may be selected to provide an optimized gain configuration for any input power level.
Abstract: A digital pre-distortion system which can provide the flexibility to model the highly non-linear distortion associated with High Efficiency RF Power Amplifiers while through a novel implementation of a least squares estimation process allows an implementation well suited for an FPGA application where limited resources and in particular memory resources are available.
November 11, 2009
Date of Patent:
October 4, 2011
Philip Brown, John Ibison, Jeremy Segar, Stephen Cooper, Frank Friedman
Abstract: In a contactless IC card system, a modulating circuit manufactured in an IC form is operable at a high power efficiency. The demodulating apparatus is configured to include: first signal output means for outputting a first output signal having a predetermined phase with respect to that of an input signal, a second signal output means for outputting a second output signal having a predetermined phase with respect to that of the input signal, gate means for gating at least the second output signal, calculation means for adding, or subtracting the first output signal and the second output signal; and control means for controlling the operation of the gate means in response to a logic level of input data.
Abstract: Disclosed is a low-noise active RC signal processing circuit, which comprises a feedforward section operable responsive to an input signal to provide an output at a predetermined gain, and a feedback section operable responsive to the output of the forward circuit to negatively feed back the output to the input signal of the feedforward section while giving a predetermined transfer characteristic to the output, so as to allow the processing circuit to have a transfer impedance characteristic equal to or less than the predetermined gain over the entire frequency range. The feedforward section is composed of a current-controlled voltage output circuit which includes a common-base transistor for receiving and inverting the input signal, and an emitter-follower transistor for outputting voltage, and has a transfer impedance defining the predetermined gain. The current-controlled voltage output circuit may also be constructed using an operational amplifier.
Abstract: A method of controlling a feedforward distortion compensation amplifier has steps of
detecting a distortion component generated in a main amplifier by coupling a signal branched from a signal input to the main amplifier and containing a plurality of carriers of different frequencies to a signal branched from an output signal from the main amplifier so that the coupling causes the carrier components to cancel each other,
recoupling the signal resulting from the coupling to the output signal from the main amplifier,
and adjusting an amplitude and phase of at least one of the signals to be recoupled so that distortion components cancel each other upon recoupling,
wherein a first and second pilot signals obtained from a first and second pilot signal sources are inserted into the input signal to or output signal from the main amplifier, parts of the signal resulting from the recoupling are taken out through branching, and the signals taken out through branching are mixed with the first and second pilot signals
June 11, 2002
Date of Patent:
June 15, 2004
Matsushita Electric Industrial Co., Ltd.
Abstract: A class-S modulator (5) receives an input signal (10) having envelope information and pulse-width modulates the input signal (10) using a reference waveform (26) from a waveform generator (25). The envelope becomes a pulse-width modulated signal is level-shifted and amplified through a pre-driver (40). A driver (50) controls switches (60, 70) which drive an output (80) into a low-pass filter (90) wherein the envelope is restored to the amplified signal for driving a power amplifier in a wide-band transceiver.
November 27, 1996
Date of Patent:
June 6, 2000
Ronald Gene Myers, Bernard Eugene Sigmon
Abstract: A transimpedance amplifier circuit includes an inverting amplifier having an input being supplied with an input current, an output carrying an output voltage and a transconductance being adjusted as a function of the input current. A coupling member is connected between the input and the output of the inverting amplifier and has a controllable impedance. A differential amplifier has one input connected to the input and another input connected to the output of the inverting amplifier. A low-pass filter is connected downstream of the differential amplifier and has an output supplying a trigger signal for the coupling member.
Abstract: A transmission-line loss equalizing circuit includes an equalizer, a gain control circuit for controlling the gain of the equalizer based upon the peak value of an equalized output, a slicer for slicing the equalized output and outputting a data pulse, a timing extraction pulse and an equalization control pulse, a DC feedback level detector for detecting a DC component of the equalized output and feeding the DC component back to the equalizer, and an attenuating circuit provided as an initial stage of the equalizer. A plurality of .sqroot.fAGC circuits constructing the equalizer are cascade-connected and constructed by a differential non-inverting amplifier.
Abstract: A current mirror circuit comprises a first current-to-voltage converter for inputting an input current, a second current-to-voltage converter, a first transistor, the collector or drain of which outputs an output current, and the emitter or source of which is connected to the second current-to-voltage converter, and a control unit for controlling a control electrode of the first transistor. The control unit refers a voltage current-to-voltage converted by the first and second current-to-voltage converters to control the first transistor so that currents flow from the control unit to the first and second current-to-voltage converters at a predetermined ratio.
Abstract: To minimize noise generation a chopper switch for a chopper stabilized operational amplifier includes a balanced bridge circuit with two pairs of high-side and low-side transistors connected in parallel. The transistors are not turned completely off but operate in the manner of variable resistors between a high-resistance level and a low-resistance level. One or more additional transistors are include to provide a parasitic capacitance in the break-before-make interval when all of the other transistors are turned off. To provide rail-to-rail operation, complementary circuits contain N-channel and P-channel transistors are connected in parallel between the input and output terminals of the chopper switch.
Abstract: The present invention provides a linearization system (100) and method (700, 800) for generating a predistorted drive signal for a nonlinear transmission path. The linearization includes: A) an analog feedback system (39), coupled to a computation unit, for determining, during a training mode, a complex error signal that linearizes the nonlinear transmission path and wherein, in an operation mode, the analog feedback system is disabled; and B) a computation unit (1), coupled to the analog feedback system and coupled to receive a complex input signal and the complex error signal, for determining, during the training mode, complex predistortion gain coefficients and, during the operation mode, generating the predistorted drive signal for the nonlinear transmission path, wherein the analog feedback system and computation unit are interconnected by interface circuitry.
September 30, 1997
Date of Patent:
September 28, 1999
Andrew Merritt Khan, George Francis Opas
Abstract: A bipolar OTA having a wide input voltage range is provided without increasing the circuit scale and current consumption. This OTA includes first to n-th differential pairs of first to 2n-th bipolar transistors whose emitters are coupled together, where n.gtoreq.2; and a common current source/sink connected to the emitters of the first to 2n-th transistors. The first to 2n-th transistors are driven by a common tail current produced by the common current source/sink. The transistors of each of the second to n-th differential pairs have a same emitter area K.sub.1 to K.sub.n-1 times as large as that of the first and second transistors, where K.sub.1 to K.sub.n-1 >1. A first input voltage as an input signal to be amplified is differentially applied across bases of the first and second transistors of the first differential pair. A second to n-th input voltages are differentially applied across corresponding bases of the third to 2n-th transistors, respectively.
Abstract: A low noise amplifier includes an input matching means of an input stage and an output matching means of an output stage, a common source transistor and a common gate transistor serially connected between the input matching means and the output matching means, a first inductor connected between said common source transistor and common gate transistor a second inductor connected between the common point of said common source transistor and common gate transistor and the output stage of said common gate transistor. Therefore, the low noise amplifier allows the points of .GAMMA..sub.opt and G.sub.max to be closer to each other so that the noise and input gain simultaneous matching is performed, thereby improving the performance.
Abstract: In a gain-variable amplifier including a dual differential amplifier circuit for amplifying an input voltage to generate an output voltage with a gain in accordance with first and second control voltages, and a control voltage generating circuit, for generating the first and second control voltages in accordance with a gain control voltage, a polarity of a difference between the first and second control voltages is unchanged, when the gain control voltage is within a control range.
Abstract: An operational amplifier having a high voltage power supply and a low voltage power supply receives first and second input signals and amplifies a voltage difference between the first and second input signals to generate an amplified signal. The operational amplifier has a first differential amplifier having a pair of first type transistors that are activated by the first and second input signals having a voltage greater than the voltage of the low voltage power supply. The first differential amplifier transmits a first output signal (S1) in response to the voltage difference between the first and second input signals. A second differential amplifier has a pair of second type transistors that are activated by the first and second input signals having a voltage smaller than the voltage of the high voltage power supply. The second differential amplifier transmits a second output signal (S2) in response to the voltage difference between the first and the second input signals.
Abstract: A bridge amplifier circuit comprising two amplifiers in bridge configuration having a feedback path from the output of one of the amplifiers to the reference input of the other amplifier, together with compensation means for reducing the voltage variation at the reference input. In this way offset and distortion are reduced, although the gain of the amplifier circuit is not affected by the presence of the feedback path.
Abstract: A controlled, saturated high frequency power amplifier, which can be used especially as a transmitting amplifier in a T/R module for a phase-controlled (radar) antenna for the X-band (8 GHz to 12 GHz). In this case, a portion of the HF output signal is utilized to generate a control signal, with which the output power is controlled nearly without loss via at least one gate connection for the HF power amplifier components, preferably, field effect transistors, that are components of the power amplifier. The power amplifier thus has a high degree of transmitting effectiveness, even with a pulsed transmitting operation.
Abstract: A differential transimpedance amplifier with reduced input impedance and increased bandwidth having a pair of input contacts, a pair of summing transistors, a pair of feedback transistors, a pair of output resistors, a pair of feedback resistors, a first and a second node and a pair of output contacts. The input contacts each being connected to one or more sources of current that are to be summed and are connected to the pair of summing transistors. The pair of feedback transistors are connected to the pair of input contacts, the pair of feedback resistors and to the first node for differentially reducing the input impedance of the pair of summing transistors and to overcome voltage excursions at the pair of input contacts to increase the operational bandwidth of the transimpedance amplifier.
Abstract: A multistage amplifier circuit comprises a current constant mode variable amplifying circuit for amplifying an input signal and current variable mode variable amplifying circuits and for further amplifying the signal amplified by the first variable amplifying circuit. An AGC voltage VAGC is commonly applied between the bases and emitters of an amplification degree control transistor of the current constant mode variable amplifying circuit and amplification degree control transistors of the current variable mode amplifying circuits. Collector currents of the transistors change exponentially with respect to the linearly-varied AGC voltage VAGC. Further, currents each proportional to the collector current of the transistor flow in the transistors. Thus, the gain PG ?dB! of the current constant mode variable amplifying circuit changes linearly with the AGC voltage VAGC.
Abstract: A digitally implemented, look-up table-based, predistortion and feed-forward correction signal processing mechanism compensates for distortion generated in the RF power amplifier. The input signal to the RF amplifier is stored for comparison with the measured the RF output. In each of predistortion and feed-forward signal processing paths, the magnitude of the complex waveform of the input signal is extracted to derive a read-out address to a dual-port RAM which stores weights to be multiplied by the input signal. In the predistortion signal processing path, the product is coupled to the RF power amplifier. In the feed-forward correction loop, the product is amplified by an auxiliary feed-forward RF amplifier and coupled into the amplified output signal path of the RF power amplifier.