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    R.F. Power amplifier
    1.
    发明公开
    R.F. Power amplifier 失效
    R.F. 功率放大器

    公开(公告)号：EP0206424A3

    公开(公告)日：1988-02-03

    申请号：EP86201084

    申请日：1986-06-23

    申请人： PHILIPS ELECTRONIC AND ASSOCIATED INDUSTRIES LIMITED ,  N.V. Philips' Gloeilampenfabrieken

    发明人： Everard, Jeremy Kenneth Arthur

    IPC分类号： H03F03/217 ,  H03F03/24

    CPC分类号： H03F3/2176

    摘要： 0 An r.f. power amplifier, typically a high efficiency, class E amplifier in which a reactive load circuit (18) is connected to a semiconductor switching device (10), the load circuit being designed to have the required input load angle and loaded Q so that the voltage across the device (10) goes to zero with zero slope before it switches on and passes current, is provided with a step recovery diode (32) connected to the device (10) to limit the voltage swing across the device (10) with no significant loss of efficiency. This allows the voltage-handling capability required of the device to be reduced or the amplifier output power to be increased by increasing the supply voltage.

    AM signal transmitter
    3.
    发明公开
    AM signal transmitter 失效
    AM信号发射器

    公开(公告)号：EP0188329A3

    公开(公告)日：1988-01-27

    申请号：EP86300099

    申请日：1986-01-08

    申请人： NEC CORPORATION

    发明人： Kobayashi, Naoki c/o NEC Corporation ,  Asakura, Takashi c/o NEC Corporation ,  Sato, Hideo c/o NEC Corporation

    IPC分类号： H03F03/24 ,  H03F03/217 ,  H03F01/06

    CPC分类号： H03F3/24

    摘要： A class D transmitter arrangement comprises a pulse width modulator (1) providing complimentary outputs B, C to a push-pull modulation amplifier (2) whose output is smooth by a low pass filter (3). The voltage of the filtered signal is stepped up by a transformer (4) to provide a component of the supply voltage for a power amplifier (5) amplifying the transmitter carrier signal. The maximum output from the transformer (4) have a peak-to-peak voltage of twice the voltage of a power supply (9) supplying both the modulation pmplifier (2) and a fixed component of the supply for the amplifier (5), through a choke (8). The power supply voltage need only be half that required in known arrangements.

    Digital audio amplifier
    5.
    发明公开
    Digital audio amplifier 失效
    数字音频放大器

    公开(公告)号：EP0172737A3

    公开(公告)日：1987-09-23

    申请号：EP85305848

    申请日：1985-08-16

    申请人： Peavey Electronics Corp.

    发明人： Taylor, Wilson E. ,  Hand, Larry E.

    IPC分类号： H03F03/217

    CPC分类号： H03F3/2171

    摘要： An extremely high fidelity digital audio amplifier having a modulator (7) for transforming an analog audio input signal into two complementary trains of pulse width modulated signals for driving power switches (80 and 81), which modulator (7) utilizes a precision triangular waveform to control the transformation. The modulator (7) employs all differential processing without saturated transistors to achieve a minimal distortion modulation system. Upon the occurrence of over-modulation, pulses from the width modulated pulse train produced by the modulator (7) are dropped, and the resulting loss of pulses is detected and fed back to a variable gain amplifier stage (3) of the system. A distortion detection system (5) for detecting the missing pulses utilizes a timing network (60 and 62) to establish the missing pulse period necessary to begin input attenuation of the audio signal by the variable gain amplifier stage (3). A reconstruction filter (13) includes a low-pass section (110) for recovering the amplified audio signal and a notch filter section (101 and 102) having notches centered to eliminate the fundamental of the switching frequency. A variable inductor (121) is employed in connection with a section of the notch filter (101 and 102) for aiding in the proper notching of the signals to maximize surpression of the switching frequency, such inductor (121) being coupled to the feedback network (9), and is adjusted by the operator.