In Cascade Amplifiers Patents (Class 330/98)
  • Patent number: 9118283
    Abstract: An amplifier circuit comprising a driver (204, 304) configured to provide a switched mode input signal, a switching mode power amplifier (206, 306) configured to receive the switched mode input signal and provide an output signal for an external load (210, 310); and a sensor (208, 308) configured to sense the impedance of the external load (210, 310) The driver is configured to set the duty cycle of the switched mode input signal in accordance with the sensed impedance of the external load (210, 310).
    Type: Grant
    Filed: September 13, 2013
    Date of Patent: August 25, 2015
    Assignee: NXP, B.V.
    Inventors: Koen Buisman, Mark Pieter van der Heijden, Mustafa Acar, Leo de Vreede
  • Patent number: 8994464
    Abstract: An amplifier and oscillator system includes a MEMS resonator and a two stage amplifier topology. The MEMS resonator is configured to generate a resonator signal. The two-stage amplifier topology is configured to amplify the resonator signal with a selected trans-impedance gain. Additionally, the two stage amplifier topology yields a feedback resistance that provides the selected trans-impedance gain.
    Type: Grant
    Filed: October 9, 2012
    Date of Patent: March 31, 2015
    Assignee: Taiwan Semiconductor Manufacturing Co., Ltd.
    Inventors: Tung-Tsun Chen, Jui-Cheng Huang
  • Patent number: 8766725
    Abstract: Apparatus and methods for frequency compensation of an amplifier are provided. In one embodiment, an integrated circuit (IC) includes an amplifier configured to amplify an input signal to generate an output signal. The IC further includes an output pad configured to receive an output signal from the amplifier and a control pad for controlling the closed-loop bandwidth of the amplifier. A compensation capacitor is electrically connected between an input of the inverting amplification block and an output of the inverting amplification block, and a switchable capacitor is electrically connected between the input of the inverting amplification block and the control pad. The control pad can be electrically connected to a DC voltage source or to the output pad to control the amplifier's closed-loop bandwidth.
    Type: Grant
    Filed: April 13, 2012
    Date of Patent: July 1, 2014
    Assignee: Analog Devices, Inc.
    Inventors: Stefano I. D'Aquino, Kimo Tam, Yukihisa Handa
  • Patent number: 8729962
    Abstract: A millimeter wave power amplifier is disclosed. In an exemplary embodiment, a MM wave power amplifier (PA) includes a plurality of amplifier stages coupled together to receive a MM wave input signal and produce an amplified MM wave output signal, and one or more feedback elements coupled across the amplifier stages, each feedback element coupled across an odd number of the amplifier stages to increase an operating bandwidth of the PA.
    Type: Grant
    Filed: December 15, 2011
    Date of Patent: May 20, 2014
    Assignee: QUALCOMM Incorporated
    Inventors: Saihua Lin, Yongwang Ding, Cheol-Woong Lee
  • Patent number: 8723602
    Abstract: The class-E amplifier can be tuned to pass only the fundamental frequency to the antenna by optimizing the second harmonics at the drain of the final PA driver transistor. A CPW in series with a capacitor between the PA transistor and the load forms a band pass filter that only allows the fundamental frequency to pass to the load of the antenna. A supply inductor to couple the drain of the final PA driver transistor to the power supply is tuned at the second harmonic with the parasitic capacitance of the drain of the PA transistor. A load capacitance is adjusted at the fundamental frequency to insure that the current waveform and voltage waveforms at the drain of the PA driver transistor do not overlap, thereby minimizing the parasitic power dissipation and allowing maximum energy to be applied to the antenna.
    Type: Grant
    Filed: August 10, 2012
    Date of Patent: May 13, 2014
    Assignee: Tensorcom, Inc.
    Inventor: Jiashu Chen
  • Patent number: 8717083
    Abstract: A method including receiving an input signal; amplifying the input signal to generate an output signal using a cascade of a plurality of amplifier stages including a first amplifier stage and a last amplifier stage; generating a voltage signal by sensing the output signal in a noninvasive manner so that the sensing results in substantially no change to the output signal; generating a current signal from the voltage signal using a transconductance amplifier; and injecting the current signal into an output node of the first amplifier stage in a noninvasive manner so that the injecting results in substantially no change to an amplification function of the first amplifier stage.
    Type: Grant
    Filed: March 14, 2013
    Date of Patent: May 6, 2014
    Assignee: Realtek Semiconductor Corp.
    Inventor: Chia-Liang Lin
  • Patent number: 8704601
    Abstract: The present invention includes a class-E power amplifier, comprising a driver stage (DS) including a first power amplifier with transistors, to which an input signal is inputted; a main stage (MS), including a second power amplifier with transistors, whose input is connected to the output of the DS; and a first LC resonator whose one end is connected to the output of the DS and the other end to the ground as an AC equivalent circuit and a second LC resonator whose one end is connected to the input of the MS and the other end to the ground as an AC equivalent circuit. In accordance with the present invention, as the voltage stress is reduced on the CMOS class-E power amplifier, the application of the high power supply voltage may be allowed and therefore the load impedance may be high while the same efficiency is maintained.
    Type: Grant
    Filed: December 15, 2010
    Date of Patent: April 22, 2014
    Assignee: SNU R&DB Foundation
    Inventors: Sang Wook Nam, Yong Hoon Song, Sung Ho Lee, Jae Jun Lee, Eun II Cho
  • Patent number: 8687821
    Abstract: An amplifier is disclosed, wherein the output stage is split between a primary output stage and a secondary stage. To minimize or eliminate any audible plop when the amplifier is switched on, the primary stage is connected, and the second stage is gradually connected using a switch. The gradual connection can be by means of varying the pulse-density of a pulse wave modulation on the switch, from fully open (0% pulse-density) to fully closed (100%). The inverse process can minimize or eliminate plop during switch-off. Separate feedback loops are switchable, from the primary and secondary stages; in a DC-coupled embodiment, the feedback loop from the secondary stage may include DC-offset cancelling circuitry, to both reduce or eliminate the plop and avoid and DC-offset current through the speaker.
    Type: Grant
    Filed: November 12, 2010
    Date of Patent: April 1, 2014
    Assignee: NXP B.V.
    Inventor: Han Martijn Schuurmans
  • Patent number: 8680918
    Abstract: A high-voltage driver amplifier for piezo haptics comprises an input amplifier having a gain greater than one, a first amplifier of an amplifier pair coupled to an output of the input amplifier, a second amplifier of the amplifier pair coupled to the output of the input amplifier, a first impedance coupled between an output of the first amplifier of the amplifier pair and an input of the input amplifier, and a second impedance coupled between the output of the first amplifier of the amplifier pair coupled to an output of the second amplifier of the amplifier pair. A substantially capacitive load is coupled to the output of the second amplifier. The substantially capacitive load is a piezo-capacitance, wherein the piezo-capacitance is employed in haptics. The second impedance, a shunt impedance, allows for a feedback of output variations between the first amplifier and the second amplifier over the first impedance.
    Type: Grant
    Filed: December 16, 2011
    Date of Patent: March 25, 2014
    Assignee: Texas Instruments Incorporated
    Inventors: Brett Earl Forejt, Mayank Garg, David John Baldwin
  • Patent number: 8610495
    Abstract: Some embodiments of the invention relate a transimpedance amplifier circuit having a negative feedback network that provides additional filtering of an out-of-band transmitted signal is provided herein. In one embodiment, the transimpedance amplifier circuit has a first pole, transimpedance amplifier having a multi-stage operational amplifier with an input terminal and an output terminal. An RC feedback network extends from the output terminal to the input terminal. A negative feedback network, extending from an internal node of the multi-stage operational amplifier to an input terminal of the single pole, transimpedance amplifier provides a negative feedback signal with an amplitude having an opposite polarity as the out-of-band transmitted signal. The negative feedback signal suppresses the out-of-band-transmitted signals within the demodulator circuit, thereby improving linearity of the transimpedance amplifier circuit.
    Type: Grant
    Filed: December 16, 2011
    Date of Patent: December 17, 2013
    Assignee: Intel Mobile Communications GmbH
    Inventors: Umut Basaran, Ashkan Naeini
  • Publication number: 20130271219
    Abstract: Apparatus and methods for frequency compensation of an amplifier are provided. In one embodiment, an integrated circuit (IC) includes an amplifier configured to amplify an input signal to generate an output signal. The IC further includes an output pad configured to receive an output signal from the amplifier and a control pad for controlling the closed-loop bandwidth of the amplifier. A compensation capacitor is electrically connected between an input of the inverting amplification block and an output of the inverting amplification block, and a switchable capacitor is electrically connected between the input of the inverting amplification block and the control pad. The control pad can be electrically connected to a DC voltage source or to the output pad to control the amplifier's closed-loop bandwidth.
    Type: Application
    Filed: April 13, 2012
    Publication date: October 17, 2013
    Applicant: Analog Devices, Inc.
    Inventors: Stefano I. D'Aquino, Kimo Tam, Yukihisa Handa
  • Publication number: 20130214857
    Abstract: A circuit for self-calibrating a gain control system samples the output of a digital amplifier coupled in series with one or more analog amplifiers to correct errors in a discrete stepped gain control. A digital gain control circuit controls both the digital amplifier and at least one analog amplifier to produce a smooth linear and continuous gain, wherein perturbations in the digital control of gain are smoothed by a signal applied to gain control circuit by a gain step correction circuit.
    Type: Application
    Filed: March 18, 2013
    Publication date: August 22, 2013
    Inventors: James Qiu, Sridhar Ramesh
  • Patent number: 8508302
    Abstract: An electronic circuit includes: first through third transistors having a control terminal, first and second terminals; a first direct current path supplying a direct current having passed through between the first terminal and the second terminal of at least one of the second transistor and the third transistor to the second terminal of the transistor at former position compared to the transistor through which the direct current passed; a second direct current path that is different from the first direct current path and supplies a direct current having passed through between the first terminal and the second terminal of at least one of the second transistor and the third transistor to the second terminal of the transistor at former position compared to the transistor through which the direct current passed; and a common coupling point coupling the first direct current path and the second direct current path in common.
    Type: Grant
    Filed: September 23, 2011
    Date of Patent: August 13, 2013
    Assignees: Sumitomo Electric Industries, Ltd., Sumitomo Electric Device Innovations, Inc.
    Inventors: Seiji Fujita, Tsuneo Tokumitsu
  • Patent number: 8471721
    Abstract: A server rack includes a main body, an electronic scale, and an alarm. The main body is used for receiving a number of servers. The electronic scale includes a pressure sensor and a microcontroller. The main body presses on the pressure sensor so that the pressure sensor can measure the pressure from the main body to obtain a pressure signal. The microcontroller analyzes the pressure signal to calculating the total weight of the main body and the servers. The alarm stores a predetermined weight threshold, which is the total weight of the main body and the maximum servers that the main body can bear. The alarm also compares the measured total weight with the predetermined weight threshold. When the measured total weight is larger than the predetermined weight threshold, the alarm alarms.
    Type: Grant
    Filed: April 12, 2011
    Date of Patent: June 25, 2013
    Assignees: Hong Fu Jin Precision Industry (ShenZhen) Co., Ltd., Hon Hai Precision Industry Co., Ltd.
    Inventors: Song-Lin Tong, Guang-Dong Yuan, Hai-Qing Zhou
  • Patent number: 8456215
    Abstract: A limiting amplifier and method are provided. In one implementation an apparatus includes a plurality of amplifier stages including a first amplifier stage and a last amplifier stage configured in a cascade arrangement, and a transconductance amplifier, wherein the first amplifier stage is configured to receive an input signal; the last amplifier stage outputs an output signal; the transconductance amplifier is configured receive a voltage signal from the last amplifier stage via a first resistor; and the transconductance amplifier is configured to output a current signal to an output node of the first amplifier stage via a second resistor in a negative feedback manner.
    Type: Grant
    Filed: September 25, 2011
    Date of Patent: June 4, 2013
    Assignee: Realtek Semiconductor Corp.
    Inventor: Chia-Liang Lin
  • Patent number: 8421531
    Abstract: A low dissipation, low distortion amplifier includes a driver amplifier stage and a main output stage, with a plurality of impedance networks providing, among other things, feedback paths from outputs of the driver and main output stages to the input of the driver stage. The impedance networks also provide coupling paths from the outputs of the driver and main output stages to the load. The impedance networks can all be formed of resistors, capacitors, or network combinations thereof. An additional feedback path can be added from the load to the driver stage to flatten out the frequency response at low frequencies. The driver and main output stages may be operated in Class AB and B modes respectively, and/or in Class G or H modes. An intermediate amplifier driver stage may be added between the driver and main output stages.
    Type: Grant
    Filed: July 6, 2011
    Date of Patent: April 16, 2013
    Assignee: THX Ltd
    Inventors: Owen Jones, Lawrence R. Fincham
  • Patent number: 8373509
    Abstract: Techniques to improve low noise amplifiers (LNAs) with noise canceling are described. LNA includes a first and a second amplifier which work together to noise cancel the noise generated at an input stage circuit. The input stage circuit receives an RF signal and is characterized by a first node and a second node. The first amplifier converts a noise voltage at the first node into a first noise current at an output of the first amplifier. The second amplifier is directly coupled to the output of the first amplifier and provides noise canceling by summing the first noise current with a second noise current generated by the second amplifier as a function of the noise voltage at the second node. The proposed techniques eliminate the need for large ac coupling capacitors and reduce the die size occupied by the LNA.
    Type: Grant
    Filed: February 9, 2012
    Date of Patent: February 12, 2013
    Assignee: QUALCOMM, Incorporated
    Inventors: Yi Zeng, Xiaoyong Li, Rahul A Apte
  • Patent number: 8374560
    Abstract: Aspects of a method and system for processing signals in a high performance receive chain may include amplifying a plurality of radio frequency signals in one or more respective one or ones of a plurality of amplifier chains in a multistandard radio frequency front-end, which may comprise one or more shared processing stages. The plurality of radio frequency signals may be compliant with a plurality of radio frequency communication standards and may be received concurrently. The one or more shared processing stages may be shared between two or more of the plurality of amplifier chains. Each of the two or more of the plurality of amplifier chains may be operable to amplify signals compliant with different radio frequency communication standards.
    Type: Grant
    Filed: September 15, 2010
    Date of Patent: February 12, 2013
    Assignee: Broadcom Corporation
    Inventors: Arya Behzad, Adedayo Ojo, Yuyu Chang, Hung-Ming Chien, Kishore Rama Rao, Guruprasad Seetharam
  • Patent number: 8305140
    Abstract: Active resistive circuitry (10, 10A, 11, 11A 25, 30, 35, or 40) includes a first current divider circuit (11) having an input (15) coupled to a first signal (Vi). The first current divider circuit (11) includes a first amplifier (13) having a first input (?) coupled to the first signal (Vi). A symmetrically bilateral first bidirectional circuit (M1a,M1b; R1) is coupled between the first input (?) of the first amplifier (13) and an output (17) of the first amplifier (13), and functions as a feedback circuit of the first amplifier (13). A symmetrically bilateral second bidirectional circuit (M2a,M2b; R2) is coupled between the output (17) of the first amplifier (13) and an output (18) of the first current divider circuit (11).
    Type: Grant
    Filed: September 7, 2011
    Date of Patent: November 6, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: Du Chen, Kemal S. Demirci
  • Patent number: 8274335
    Abstract: An apparatus for implementing a front end core for a transimpedance amplifier includes an input transimpedance stage that receives an FE core input signal and responsively generates an output transimpedance gain signal. A first output gain stage receives the output transimpedance gain signal and responsively generates an FE core output signal. A phase inverter stage also receives the output transimpedance gain signal and responsively generates an inverted output signal. A second output gain stage then receives the inverted output signal and responsively generates an inverted FE core output signal.
    Type: Grant
    Filed: April 14, 2011
    Date of Patent: September 25, 2012
    Assignee: Sony Corporation
    Inventor: Jeremy Chatwin
  • Publication number: 20120218043
    Abstract: An amplifier comprises a main amplification stage and an auxiliary amplification stage. An input of the main amplification stage and an input of the auxiliary amplification stage are coupled to a common node, and an output of the main amplification stage is coupled to an output node. During activation, before power is supplied to the main amplification stage, the output node is coupled to a reference voltage (VREF). A quiescent voltage is then established at the common node by coupling power to the auxiliary amplification stage. Only then is power coupled to the main amplification stage and the reference voltage (VREF) de-coupled from the output node.
    Type: Application
    Filed: October 29, 2010
    Publication date: August 30, 2012
    Applicant: ST-Ericsson SA
    Inventor: Robert Hwat Hian Teng
  • Publication number: 20120169418
    Abstract: A low dissipation, low distortion amplifier includes a driver amplifier stage and a main output stage, with a plurality of impedance networks providing, among other things, feedback paths from outputs of the driver and main output stages to the input of the driver stage. The impedance networks also provide coupling paths from the outputs of the driver and main output stages to the load. The impedance networks can all be formed of resistors, capacitors, or network combinations thereof. An additional feedback path can be added from the load to the driver stage to flatten out the frequency response at low frequencies. The driver and main output stages may be operated in Class AB and B modes respectively, and/or in Class G or H modes. An intermediate amplifier driver stage may be added between the driver and main output stages.
    Type: Application
    Filed: July 6, 2011
    Publication date: July 5, 2012
    Applicant: THX, LTD
    Inventors: Owen Jones, Lawrence R. Fincham
  • Patent number: 8189713
    Abstract: A wireless communication device includes an RF transceiver configured to up convert a base band signal to a transmitting RF signal, a configurable matrix power amplifier circuit configured to amplify the transmitting RF signal to produce an amplified RF signal, and an antenna configured to transmit a wireless signal in response to the amplified RF signal.
    Type: Grant
    Filed: January 18, 2010
    Date of Patent: May 29, 2012
    Assignee: Micro Mobio Corporation
    Inventors: Inui Shinsuke, Ikuroh Ichitsubo, Shigeru Watanabe
  • Patent number: 8164385
    Abstract: An amplifier circuit includes a first amplifier amplifying an input signal and outputting a first amplified signal, a second amplifier amplifying the first amplified signal and outputting a second amplified signal, and a feedback circuitry feeding back the second amplified signal to the input of the second amplifier. The feedback circuitry includes a feedback transistor that keeps the input level of the second amplifier constant.
    Type: Grant
    Filed: August 26, 2009
    Date of Patent: April 24, 2012
    Assignee: Fujitsu Limited
    Inventors: Yukito Tsunoda, Mariko Sugawara
  • Patent number: 8159303
    Abstract: An operational amplifier includes an input stage amplifier that receives an input signal, an output stage amplifier that amplifies a signal output from the input stage amplifier and outputs the signal, a capacitor that is connected between an input node and an output node of the output stage amplifier, and a charge and discharge control circuit that controls a charge and discharge current of the capacitor.
    Type: Grant
    Filed: January 11, 2010
    Date of Patent: April 17, 2012
    Assignee: Renesas Electronics Corporation
    Inventors: Kouichi Nishimura, Yoshihiko Hori
  • Patent number: 8159293
    Abstract: A nested transimpedance amplifier circuit including a first power source, a second power source, a charge pump module and a transimpedance amplifier. The first power source is at a first voltage. The second power source is at a second voltage. The second voltage is different than the first voltage. The charge pump module (i) receives the first voltage and the second voltage and (ii) generates a third voltage based on the first voltage and the second voltage. The first transimpedance amplifier includes an input, an output and a first operational amplifier. The input of the first transimpedance amplifier receives an input voltage. The output of the first transimpedance amplifier outputs an output voltage. The first operational amplifier receives the third voltage. The first transimpedance amplifier generates the output voltage based on the third voltage and the input voltage.
    Type: Grant
    Filed: August 17, 2010
    Date of Patent: April 17, 2012
    Assignee: Marvell International Ltd.
    Inventor: Sehat Sutardja
  • Patent number: 8102214
    Abstract: Provided is controlled-gain wideband feedback low-noise amplifier. The controlled-gain wideband feedback low-noise amplifier includes: a feedback amplifier configured to isolate an input signal and an output signal obtained by amplifying the input signal, feed back the output signal to the input signal to amplify wideband input signals, resonate a low-frequency band signal among the wideband input signals to amplify the low-frequency band signal among the wideband input signals, and be switched in accordance with a control signal to control an amplification gain of the low-frequency band signal among the wideband input signals; and a cascode amplifier configured to amplify a high-frequency band signal among the wideband signals inputted from the feedback amplifier, and be switched in accordance with a control signal to control an amplification gain of the high-frequency band signal among the wideband signals.
    Type: Grant
    Filed: August 25, 2010
    Date of Patent: January 24, 2012
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Bong-Hyuk Park, Kwang-Chun Lee
  • Patent number: 8098840
    Abstract: A multi-channel output device for a multimedia device includes a plurality of reception ends, an amplifier having an input end and an output end, a plurality of sound output devices for outputting sound, a first switching unit coupled between the plurality of reception ends and the input end of the amplifier for coupling a reception end of the plurality of reception ends to the input end of the amplifier according to a control signal, a second switching unit coupled between the output end of the amplifier and the plurality of sound output devices for coupling the output end of the amplifier to a sound output device of the plurality of sound output devices according to the control signal, and a control unit coupled to the first switching unit and the second switching unit for outputting the control signal.
    Type: Grant
    Filed: December 23, 2008
    Date of Patent: January 17, 2012
    Assignee: Anpec Electronics Corporation
    Inventor: Chiung-Ching Ku
  • Patent number: 8081032
    Abstract: A low noise amplifier (LNA) includes an LNA input that receives a signal from an antenna. The LNA also includes an internal amplifier with an input that is coupled to the LNA input, as well as an internal filter with an input coupled to the output of the internal amplifier and an output coupled to the input of the internal amplifier. The coupling of the output of the internal filter to the input of the internal amplifier provides feedback to the input of the internal amplifier. The internal filter is configured to pass signals within a frequency range through to the output of the internal filter.
    Type: Grant
    Filed: August 29, 2008
    Date of Patent: December 20, 2011
    Assignee: Project FT, Inc.
    Inventor: Farbod Aram
  • Patent number: 8072262
    Abstract: A chopper-stabilized circuit (1) includes pre-chopping circuitry (26) for chopping an input signal (Vin) at a first frequency to generate a first signal. Input chopping circuitry (9) chops the first signal at a second frequency substantially greater than the first frequency to produce a second signal. The first frequency is a sub-harmonic of the second frequency. Post-chopping circuitry (30) chops the second chopped signal at the first frequency to produce a third signal that is applied to an input of a signal conditioning circuit (2). The output chopping circuitry (10) chops an output of the signal conditioning circuit at the second frequency to generate a fourth signal. The fourth signal is filtered.
    Type: Grant
    Filed: June 28, 2010
    Date of Patent: December 6, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: Rodney T. Burt, Joy Y. Zhang
  • Patent number: 8058931
    Abstract: An apparatus for an improved operational amplifier. The disclosed improved operational amplifier comprises an operational amplifier, a first feedback circuit, and one or more secondary feedback circuits. The operational amplifier include a plurality of serially coupled gain stages and is configured so that an output of each gain stage drives an input of a next gain stage and an output of a last gain stage drives a load external to the improved operational amplifier. The first feedback circuit is coupled between an output of a designated gain stage and an output of a previous gain stage to provide a first feedback to the previous gain stage. Each secondary feedback circuit provides an additional feedback to the output of the previous gain stage.
    Type: Grant
    Filed: April 27, 2010
    Date of Patent: November 15, 2011
    Assignee: Linear Technology Corporation
    Inventor: Ping Zhou
  • Patent number: 8013676
    Abstract: A high-efficiency power amplifier is provided, including a drive amplifier and a final power amplifier, and further including a first digital pre-distortion (DPD) correction module and a second DPD correction module. The first DPD correction module is configured to pre-distort nonlinear characteristics of drive signals output by the drive amplifier, and the second DPD correction module is connected to the first DPD correction module in series, and is configured to pre-distort nonlinear characteristics of amplified signals output by the final power amplifier. Another high-efficiency power amplifier is also provided, including a drive amplifier and a final power amplifier, and further including a second multi-path control module, a fourth DPD correction module, and a second gating module. The overall efficiency of the high-efficiency power amplifier is increased by improving the working efficiency of the drive amplifier.
    Type: Grant
    Filed: June 16, 2010
    Date of Patent: September 6, 2011
    Assignee: Huawei Technologies Co., Ltd.
    Inventors: Yongge Su, Siqing Ye, Dandong He, Weimin Yin, Xikun Zhang, Xiaolun Wang, Qianhua Wei
  • Patent number: 8004355
    Abstract: A low dissipation, low distortion amplifier includes a driver amplifier stage and a main output stage, with a plurality of impedance networks providing, among other things, feedback paths from outputs of the driver and main output stages to the input of the driver stage. The impedance networks also provide coupling paths from the outputs of the driver and main output stages to the load. The impedance networks can all be formed of resistors, capacitors, or network combinations thereof. An additional feedback path can be added from the load to the driver stage to flatten out the frequency response at low frequencies. The driver and main output stages may be operated in Class AB and B modes respectively, and/or in Class G or H modes. An intermediate amplifier driver stage may be added between the driver and main output stages.
    Type: Grant
    Filed: February 25, 2010
    Date of Patent: August 23, 2011
    Assignee: THX Ltd.
    Inventors: Owen Jones, Lawrence R. Fincham
  • Patent number: 7986185
    Abstract: A rail-to-rail Miller compensation method without feed forward path includes forming a first compensation branch including a first amplifier, wherein an input of the first amplifier is electrically connected with an output of a second stage gain amplifier, the second stage gain amplifier is electrically connected the first stage gain amplifier in series forming an operational amplifier; and forming a second compensation branch including a second amplifier, wherein a dual relation is provided between an input stage of the first amplifier and that of the second amplifier, namely, if the input stage of the first amplifier is N-type, the input stage of the second amplifier is P-type, and vice versa. The present invention is capable of achieving the rail-to-rail output range without affecting the system stability. The N-type and P-type inputs are simultaneously applied to the input of the amplifier of the compensation branches.
    Type: Grant
    Filed: June 3, 2010
    Date of Patent: July 26, 2011
    Assignee: IPGoal Microelectronics (SiChuan) Co., Ltd.
    Inventor: Junwei Huang
  • Patent number: 7978007
    Abstract: The invention relates to a feedback network (60) for cascade amplifiers (200), which comprises an active stage (30) to feed signal back to a first internal node (65) at the output of the first amplifier stage (61) of the cascade. The invention further relates to a feedback network (60) which comprises said active feedback stage (30) with said first internal amplifier node (65) connection and a feedback resistor (10) connected from said cascade amplifier output port (out) to its input port (in).
    Type: Grant
    Filed: December 29, 2008
    Date of Patent: July 12, 2011
    Inventor: Esa Tiiliharju
  • Patent number: 7948309
    Abstract: An amplifier circuit includes a transconductance amplifier at an input side of the amplifier circuit, a transimpedance amplifier connected to an output of the transconductance amplifier, and a voltage amplifier connected to an output of the transimpedance amplifier. The transconductance amplifier and the transimpedance amplifier form a low-impedance node at an interface thereof. A feedback circuit is connected between an output of the voltage amplifier and the low-impedance node between the transconductance amplifier and the transimpedance amplifier. The transconductance amplifier, the transimpedance amplifier, and the voltage amplifier form a main amplifier stage. The feedback circuit senses an imbalance in an output of the main amplifier stage, whereby a correction signal is integrated and negatively fed back to the low-impedance node between the transconductance amplifier and the transimpedance amplifier.
    Type: Grant
    Filed: January 16, 2009
    Date of Patent: May 24, 2011
    Assignee: University of Macau
    Inventors: Pui-In Mak, Seng-Pan U, Rui P. Martins
  • Publication number: 20110095817
    Abstract: Disclosed is a signal amplifying device which includes an overcurrent detection circuit, a first inverting amplifying circuit amplifying an input signal, and a second inverting amplifying circuit amplifying an output of the first inverting amplifying circuit. The overcurrent detection circuit includes a comparison circuit and a decision circuit. The comparison circuit compares the voltage of the input signal with the voltage of an output of the second inverting amplifying circuit, and generates a signal responsive to the comparison result. The decision circuit detects overcurrent from the signal output by the comparison circuit.
    Type: Application
    Filed: October 7, 2010
    Publication date: April 28, 2011
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Toshimi YAMADA
  • Patent number: 7893760
    Abstract: An amplifier circuit including: a multistage amplifier unit including an input-stage transistor and an output-stage transistor and configured to amplify an input signal and to output an amplified signal; and a feedback unit including a first feedback transistor, a second feedback transistor, and a feedback resistor, and configured to feed back the amplified signal to an input of the output-stage transistor in the multistage amplifier unit via the first feedback transistor, the second feedback transistor, and the feedback resistor.
    Type: Grant
    Filed: August 26, 2009
    Date of Patent: February 22, 2011
    Assignee: Fujitsu Limited
    Inventors: Mariko Sugawara, Yukito Tsunoda
  • Patent number: 7859330
    Abstract: Systems and methods for characterizing amplifiers. A system for characterizing an amplifier in accordance with the present invention comprises a Gaussian signal source for generating a signal in the frequency domain, a notch filter, coupled to the Gaussian Noise source, wherein the notch filter has a notch at a specified frequency and a frequency bandwidth, the frequency bandwidth encompassing the specified frequency, an Inverse Fast Fourier Transform device, coupled to an output of the notch filter, a normalization device, coupled to the Inverse Fast Fourier Transform device, an amplifier under test, coupled to the normalization device, for amplifying the signal generated by the Gaussian signal source, and a measurement device, coupled to an output of the amplifier, for measuring a power output of the amplifier in the frequency bandwidth and a noise output at the specified notch frequency, and for calculating the ratio between the power output and the noise output.
    Type: Grant
    Filed: April 9, 2009
    Date of Patent: December 28, 2010
    Assignee: The DIRECTV Group, Inc.
    Inventors: Guangcai Zhou, Tung-Sheng Lin, Dennis Lai, Joseph Santoru, Ernest C. Chen, Shamik Maitra, Cecilia Comeaux
  • Publication number: 20100321112
    Abstract: Presently many audio chips suffer from pop issues, which is especially serious for single ended audio drivers. An audio pop is a disturbance in the output caused by a sudden transition of chip power, particularly when a chip is powered on or powered off. Furthermore, compensation networks included in the amplifiers on audio chips for stability offer a significant path for transmitting power disturbances to the output. Hence, circuitry is developed to suppress pops in the output stages of an amplifier.
    Type: Application
    Filed: June 19, 2009
    Publication date: December 23, 2010
    Applicant: CONEXANT SYSTEMS, INC.
    Inventors: Xin Fan, Christian Larsen, Lorenzo Crespi
  • Patent number: 7821335
    Abstract: The variable gain amplifier includes a bias circuit (BC) 1, a matching circuit (MC) 2, a variable gain resistive feedback amplifier (FA) 3 and an output follower (EA) 4. The resistance values of the load resistance Rc and feedback resistance Rf are changed in cooperation. In a case of making the load resistance Rc a high resistance to set the low noise amplifier to a high gain, the feedback resistance Rf is also made a high resistance, the feedback time constant ?fb(c1)?2?·RfCbe/(1+gmRc) of the closed loop of the resistive negative feedback amplifier 3 becomes substantially constant, and then the amplifier has a gain small in frequency dependency over a wide bandwidth. In a case of making the load resistance Rc a low resistance to set the low noise amplifier to a low gain, the feedback resistance Rf is also made a low resistance. The feedback resistance Rf with the low resistance increases the negative feedback quantity, and thus the amplifier is set to a low gain.
    Type: Grant
    Filed: October 16, 2008
    Date of Patent: October 26, 2010
    Assignee: Renesas Electronics Corporation
    Inventors: Nobuhiro Shiramizu, Toru Masuda
  • Patent number: 7808311
    Abstract: A nested transimpedance amplifier circuit includes a first-order nested transimpedance amplifier having an input and an output. The first-order nested transimpedance amplifier is configured to be powered by a first voltage. A charge pump module is configured to receive the first voltage and a second voltage. The second voltage is different from the first voltage. The charge pump module generates a third voltage based on the first voltage and the second voltage. A first operational amplifier has an input and an output. The input of the first operational amplifier communicates with the output of the zero-order transimpedance amplifier, and the first operational amplifier is configured to be powered by the third voltage.
    Type: Grant
    Filed: November 30, 2009
    Date of Patent: October 5, 2010
    Assignee: Marvell World Trade Ltd.
    Inventor: Sehat Sutardja
  • Publication number: 20100237936
    Abstract: An amplifier circuit, includes: a first amplifier; a second amplifier; a first capacitor connected to the first amplifier; a second capacitor having one terminal connected to the first amplifier, another terminal connected to the second input terminal; and a first switch circuit switching a connection of the output terminal, the another terminal of the first capacitor, the first input terminal and the second input terminal, and switching supplying a reference potential supply, the first switch circuit including: a first state connecting the first input terminal to the second input terminal, connecting the output terminal to the another terminal of the first capacitor, and supplying the second input terminal with the reference potential, a second state connecting the first input terminal to the another terminal of the first capacitor and providing the output terminal and the second input terminal in an open state.
    Type: Application
    Filed: March 11, 2010
    Publication date: September 23, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Toru Takeda
  • Patent number: 7791411
    Abstract: An amplifier arrangement and a method for amplifying a signal, the arrangement including a transistor to amplify an input signal and to provide an intermediate signal. The intermediate signal is amplified to form an output signal which is fed back to the transistor.
    Type: Grant
    Filed: June 19, 2007
    Date of Patent: September 7, 2010
    Assignee: Austriamicrosystems AG
    Inventors: Thomas Carl Fröhlich, Nicole Heule
  • Publication number: 20100164618
    Abstract: The invention relates to a feedback network (60) for cascade amplifiers (200), which comprises an active stage (30) to feed signal back to a first internal node (65) at the output of the first amplifier stage (61) of the cascade. The invention further relates to a feedback network (60) which comprises said active feedback stage (30) with said first internal amplifier node (65) connection and a feedback resistor (10) connected from said cascade amplifier output port (out) to its input port (in).
    Type: Application
    Filed: December 29, 2008
    Publication date: July 1, 2010
    Inventor: Esa Tiiliharju
  • Patent number: 7737777
    Abstract: An amplifier system includes a first amplifier stage having an input and an output. A second amplifier stage has an input and an output, the input of the second amplifier stage being connected to the output of the first amplifier stage. A transistor has a control terminal, a first terminal, and a second terminal, the first terminal of the transistor being coupled to the output of the first amplifier stage and the input of the second amplifier stage. A first capacitance has a first terminal and a second terminal, the first terminal of the first capacitance being connected to the input of the first amplifier stage, the second terminal of the first capacitance being connected to the second terminal of the transistor. A first current source to source current to amplifier system, the first current source being is connected to the output of the first amplifier stage. A second current source will sink current from the amplifier system.
    Type: Grant
    Filed: December 2, 2008
    Date of Patent: June 15, 2010
    Assignee: Marvell World Trade Ltd.
    Inventors: Farbod Aram, Sehat Sutardja
  • Patent number: 7672648
    Abstract: System for linear amplitude modulation. Apparatus is provided for linear amplitude modulation of an amplifier. The apparatus includes a processing circuit that receives an amplitude modulation signal and produces one or more amplifier control signals that are coupled to the amplifier. The apparatus also includes a feedback circuit that generates a feedback signal from an output of the amplifier that is input to the processing circuit; and a network that controls a bias of the amplifier in response to the feedback signal to linearize the amplifier's amplitude control.
    Type: Grant
    Filed: June 27, 2005
    Date of Patent: March 2, 2010
    Assignee: Quintics Holdings
    Inventors: John Groe, Naone Farias, Burcin Baytekin, Carrie Lo
  • Patent number: 7659780
    Abstract: A gain control circuit including a resistor with a first terminal and a second terminal; an operational amplifier with an inverting terminal thereof electrically coupled to said first terminal of said resistor; a non-inverting terminal thereof; and an output terminal thereof; an amplifier circuit for transforming the voltage change of said operational amplifier output into a substantially exponential current change; wherein the output of said amplifier circuit is electrically coupled to said inverting terminal of said operational amplifier. The above described gain control circuit is able to perform wide bandwidth input signal buffering with linearity under low voltage and low power conditions. The circuit also offers low output impedances without the need of additional buffers and hence minimizing circuit size and manufacturing costs.
    Type: Grant
    Filed: November 29, 2007
    Date of Patent: February 9, 2010
    Assignee: Hong Kong Applied Science and Technology Research Institute Co., Ltd.
    Inventors: Chit Ah Mak, Chun Fai Wong, Lap Chi Leung, Xiaofei Kuang, Jennifer Shuet Yan Ho, David Kwok Kuen Kwong
  • Patent number: 7633338
    Abstract: An amplifier circuit comprises a first capacitance having one end that communicates with an input of a first amplifier stage. An amplifier has a first gain, an input that communicates with an opposite end of the first capacitance, and an output. A second capacitance has a first end that communicates with the output of the amplifier and an opposite end that communicates with an input of a second amplifier stage. A broadband buffer has an input that communicates with the output of the amplifier and an output that communicates with the one end of the second capacitance.
    Type: Grant
    Filed: July 18, 2008
    Date of Patent: December 15, 2009
    Assignee: Marvell International, Ltd
    Inventor: Farbod Aram
  • Patent number: 7626453
    Abstract: A nested transimpedance amplifier (TIA) circuit comprises a zero-order TIA having an input and an output. A first operational amplifier (opamp) has an output and an input that communicates with said output of said zero-order TIA. A first power supply input applies a first voltage to the zero-order TIA. A second power supply input receives a second voltage. A charge pump module develops a third voltage based on the first voltage and the second voltage, wherein the third voltage is applied to the opamp.
    Type: Grant
    Filed: July 9, 2008
    Date of Patent: December 1, 2009
    Assignee: Marvell World Trade Ltd.
    Inventor: Sehat Sutardja