Unwanted Oscillation Or Radiation Prevention Patents (Class 455/317)
  • Patent number: 4661995
    Abstract: A multi-superheterodyne receiver having a first local oscillator for generating a first local frequency signal, a first frequency converter for converting to a first intermediate frequency signal a received signal in response to the first local frequency signal, a second local oscillator for generating a second local frequency signal, a second frequency converter for converting to a second intermediate frequency signal the first intermediate frequency signal in response to the second local frequency signal, includes judging circuitry for judging if a residual spurious component is generated when harmonic waves of at least one of the local frequency signals are at certain frequencies.
    Type: Grant
    Filed: September 9, 1986
    Date of Patent: April 28, 1987
    Assignee: Anritsu Electric Co., Limited
    Inventor: Toshihiro Kashiwagi
  • Patent number: 4654888
    Abstract: An image suppression mixer of the waveguide type is disclosed which includes a waveguide signal input terminal at one end of a waveguide, a local oscillation input terminal at the other end of the waveguide, a mixer diode inserted within the waveguide and an IF signal output terminal connected to the mixer diode. At least the width of the waveguide on the side of the waveguide signal input terminal is selected to be a cutoff dimension for the image frequencies f.sub.m and the local oscillation frequency f.sub.1 the waveguide signal frequencies f.sub.2, the local oscillation frequency f.sub.1 and the image frequencies f.sub.m are correlated as f.sub.m <f.sub.1 <f.sub.s.
    Type: Grant
    Filed: May 20, 1985
    Date of Patent: March 31, 1987
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Tomozo Ohta, Hiroshi Nakano
  • Patent number: 4654887
    Abstract: A wideband enhancement sum mixer is shown to comprise a pair of matched GaAs diodes operative with a printed circuit wherein a portion of at least the sum signal, i.e., the sum of a radio frequency signal and a local oscillator signal, is caused to be mixed with the second harmonic of the local oscillator signal to produce an intermediate frequency signal in phase with the intermediate frequency signal resulting from mixing of the radio frequency signal and the local oscillator signal.
    Type: Grant
    Filed: November 4, 1985
    Date of Patent: March 31, 1987
    Assignee: Raytheon Company
    Inventors: Michael T. Murphy, William R. Connerney
  • Patent number: 4654886
    Abstract: A local oscillator null circuit and method for use in tuning a wideband, heterodyne receiver relatively close to zero frequency without experiencing excessive feedthrough from a local oscillator to an associated IF stage in the receiver. The local oscillator is connected to circuit means for generating a derivative signal proportional to the local oscillator signal and shifted in phase with respect thereto by a desired amount determined by the phase difference between the local oscillator signal and the signal in the mixer output spectrum which is at the local oscillator frequency. The null circuit combines the derivative signal with the mixer output signal proportionally to produce a null at the local oscillator frequency.
    Type: Grant
    Filed: April 25, 1985
    Date of Patent: March 31, 1987
    Assignee: IFR, Inc.
    Inventor: Harold N. Selim
  • Patent number: 4648128
    Abstract: A microwave integrated circuit comprises a shield case having a pair of opposed first and second end walls, a pair of side walls and top and bottom walls, and a dielectric substrate on the bottom wall. First and second interconnected integrated circuit portions are arranged on the substrate between the first and second end walls. An input strip line is arranged on the substrate, the strip line having one end coupled to the input of the first integrated circuit portion and the other end terminating at a position spaced from the first end wall by a distance approximately equal to an integral multiple of the half wavelength of a signal propagating in the shield case. An elongated coupling member is disposed in parallel with the first end wall, the coupling member extending from the other end of the input strip line to an external circuit.
    Type: Grant
    Filed: May 30, 1984
    Date of Patent: March 3, 1987
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroshi Saka, Toshihide Tanaka
  • Patent number: 4648129
    Abstract: A frequency converter includes a mixer, a local oscillator connected to the mixer by a line which transmits a local oscillator signal to the mixer and a starter circuit for supplying a transient bias current to the mixer for insuring the start of the local oscillations.
    Type: Grant
    Filed: August 17, 1984
    Date of Patent: March 3, 1987
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kenji Hirai, Hideki Torizuka
  • Patent number: 4633520
    Abstract: A prescaler input circuit for a frequency converter unit uses a strip line type of directional coupler to isolate the prescaler unit from the frequency converter unit, eliminate beat interference and erroneous frequency dividing operation, and provide a simple and economical structure. The coupler has the prescaler input line inductively coupled to a local oscillator injection element and grounded through a resistor. An earth line is arranged in proximity to the injection lead to provide impedance matching for the coupler.
    Type: Grant
    Filed: January 10, 1984
    Date of Patent: December 30, 1986
    Assignee: Alps Electric Co., Ltd.
    Inventor: Mitsunari Okazaki
  • Patent number: 4601063
    Abstract: The output of a doubly-balanced mixer of a television tuner is terminated by a network which exhibits the characteristic impedance of the mixer for both the sum and difference frequency components. The difference frequency component termination simply consists of an inductor and a capacitor connected as a series-tuned circuit and a resistive element connected in series between the output of the mixer and signal ground. The inductor and capacitor are selected resonate at a frequency in the passband of the IF section and the resistive element is selected to exhibit the characteristic impedance of the mixer. The sum frequency component termination simply consists of a capacitor and a resistive element connected in series between the output of the mixer and signal ground. The capacitor is selected to exhibit negligible impedance just below the lowest frequency of the sum frequency component and the resistive element is selected to exhibit the characteristic impedance of the mixer.
    Type: Grant
    Filed: February 28, 1985
    Date of Patent: July 15, 1986
    Assignee: RCA Corporation
    Inventor: Timothy W. Price
  • Patent number: 4584715
    Abstract: An image rejection mixer circuit comprises a pair of mixers (1, 2) to which are supplied input signals from an input terminal (9) and oscillation signals in mutual quadrature from an oscillator (11). The mixer output signals are combined in a combining means (19) to produce at its output (20, 21) a frequency-translated wanted signal free from frequency-translated image signals. The combining means comprises an acoustic surface wave filter and, in order to avoid the necessity of providing it with a pair of input transducers, with the consequent increase in the area of piezo-electric substrate that would entail, it is provided with a single input transducer of the four-phase or pseudo four-phase type.
    Type: Grant
    Filed: October 9, 1984
    Date of Patent: April 22, 1986
    Assignee: U.S. Philips Corporation
    Inventors: Nicolaas J. Baars, Jonathan R. Quartly
  • Patent number: 4545072
    Abstract: A synthesizer radio frequency (RF) signal receiver (FIG. 1) for single sideband radios is described that can eliminate interference due to internally generated spurious signals, commonly referred to as "whistler spurs". The unique receiver includes first and second mixers (102 and 106), which are intercoupled by a 75 mHz crystal filter (104) having a 20 kHz passband, and which are each coupled to signals from voltage controlled oscillators (120 and 140). The first IF frequency provided by the first mixer (102) varies about 75 mHz, and the second IF frequency provided by the second mixer (106) is fixed at 11.4 mHz. The second mixer (106) is coupled to 11.4 mHz stages (108) which have a 2.7 kHz passband. The 11.4 mHz stages (108) are followed by another mixer (110) and audio stages (112) for demodulating audio signals from the received RF signal, which are then applied to a speaker (114).
    Type: Grant
    Filed: December 5, 1983
    Date of Patent: October 1, 1985
    Assignee: Motorola, Inc.
    Inventors: Frank R. Skutta, Thomas R. Klaus
  • Patent number: 4531236
    Abstract: A microwave integrated circuit frequency converter includes a first filter (30) for a signal frequency and a second filter (32) for a local oscillator frequency connected at one terminal thereof with one terminal of the signal frequency filter (30) by a line (38), (40) having a predetermined electrical length. A parallel stub line (42) is short-circuited at one end thereof. A diode (34) is connected at its one end to a third filter (36) which is adapted to reflect the signal and local oscillator frequencies while passing an intermediate frequency. The diode (34) is connected at the other end to a line (41).
    Type: Grant
    Filed: December 8, 1982
    Date of Patent: July 23, 1985
    Assignee: Nippon Electric Co., Ltd.
    Inventor: Hiroyuki Ishihara
  • Patent number: 4509208
    Abstract: A frequency conversion unit comprising a local oscillator, first and second mixers, first and second hybrid circuits. The mixers receive, via the first hybrid circuit, local oscillation outputs from the local oscillator, and the second hybrid circuit receives outputs from the first and second mixers, producing a frequency conversion output signal therefrom. Intermediate frequency signals used in the first and second mixers are .pi. radians out of phase with each other. The first hybrid circuit produces outputs for the first and second mixers having a predetermined phase difference of .phi..sub.1 therebetween. The second hybrid circuit receives outputs from the first and second mixers and combines them after making a phase difference of (.pi.-.phi..sub.1) therebetween.
    Type: Grant
    Filed: April 5, 1983
    Date of Patent: April 2, 1985
    Assignee: Fujitsu Limited
    Inventors: Hiroyuki Sogo, Zenichi Ohsawa, Isamu Umino, Haruki Nishida
  • Patent number: 4449245
    Abstract: An improved active balanced mixer for developing an IF signal by combining an RF signal and a local oscillator signal while providing high conversion gain. The mixer utilizes a series resonant circuit resonant at the IF frequency to reduce degenerative feedback effects at the IF frequency, thereby increasing conversion gain. Circuit is particularly adapted for a receiver in which the received RF signal is relatively close to the receivers IF frequency.
    Type: Grant
    Filed: March 22, 1982
    Date of Patent: May 15, 1984
    Assignee: Motorola Inc.
    Inventor: Duane C. Rabe
  • Patent number: 4412351
    Abstract: A microwave mixing circuit comprises a main transmission line having an input port for receiving an input high frequency and an output port, a band pass filter responsive to a local oscillation frequency, first and second band stop filters, and a mixing diode connected to the output port. The local oscillation frequency applied via the band pass filter to the main transmission line is prevented from being transmitted toward the input port because of the first band stop filter, while an image frequency produced by the diode is reflected by the second band stop filter to be applied to the diode.
    Type: Grant
    Filed: October 23, 1981
    Date of Patent: October 25, 1983
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroshi Onishi, Sadahiko Yamashita, Mitsuo Makimoto
  • Patent number: 4408352
    Abstract: The present invention reduces the distortion components produced from high power level mixing through a set of adaptive cancelling circuits which utilize a low power level mixing of the same signals to provide a signal which is adaptively cancelled with a signal representative of the high power level signal including distortion to provide an output signal which comprises substantially only the distortion components found in the high power level signal. These distortion components are then adaptively cancelled or combined with the high power level signal including distortion to provide an output signal which comprises the primary signal and insignificant levels of noise and distortion.
    Type: Grant
    Filed: May 10, 1982
    Date of Patent: October 4, 1983
    Assignee: Rockwell International Corporation
    Inventor: Charles H. Dudding
  • Patent number: 4393274
    Abstract: An AM stereo receiver for receiving AM stereo broadcasting of an AM-PM or AM-FM system. Between an IF AM signal amplifier and an limiter is interposed a 5 or more frequency multiplier so that the frequency of a spurious signal radiated from the limiter may lie outside of the frequency range handled by the RF tuner.
    Type: Grant
    Filed: August 18, 1981
    Date of Patent: July 12, 1983
    Assignee: Trio Kabushiki Kaisha
    Inventor: Yukihiko Miyamoto
  • Patent number: 4355420
    Abstract: A frequency converter has first, second and third terminals which receive a first signal having a first frequency band, a local oscillation signal, and a second signal having a second frequency band. The first signal and the local oscillation signal are mixed to generate the second signal. A first branching circuit is connected between the second terminal and the frequency mixer, for branching part of the local oscillation signal. A first part of the branched local oscillation signal, which is supplied from the first branching circuit, and a first leaked local oscillation signal are applied from the frequency mixer to the first terminal. The phase and amplitude of the first branched local oscillation signal are adjusted so that the first branched local oscillation signal and the first leaked local oscillation signal have equal amplitude and are reversed in phase to cancel each other.
    Type: Grant
    Filed: December 2, 1980
    Date of Patent: October 19, 1982
    Assignee: Nippon Electric Co., Ltd.
    Inventor: Hiroyuki Ishihara