Parasitic signal suppression circuit for an extremely high frequency oscillator

• US 5,214,395 A
• Filed: 11/22/1991
• Issued: 05/25/1993
• Est. Priority Date: 06/29/1991
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yun, Ki-ho
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US07/796,443
• Time in Patent Office: 550 Days
• Field of Search: 331/74, 331/75, 331/77, 331/96, 331/99, 331/107 SL, 331/117 D, 331/25, 455/318, 455/319, 455/320, 333/175, 333/176, 333/204, 328/165, 328/167, 330/53, 330/286, 330/302, 330/303, 330/306
• US Class Current: 331/77
• CPC Class Codes: H03B 1/04 Reducing undesired oscillations, e.g. harmonics

Abstract

An extremely high frequency parasitic signal suppression circuit for use in a local oscillator of an extremely high frequency radio or satellite communication system to eliminate parasitic signals included in a local oscillation signal. A first direct current cut-off device consisting of a microstrip line is connected between the output terminal of a phase-locked oscillator and the input of an amplifier, and to a first low pass filter to supply a direct current source for the amplifier. A second direct current cut-off device and second low pass filter are connected to the output terminal of the amplifier in the same manner as the input terminal.

Claims

1. A parasitic signal suppression circuit for an extremely high frequency (EHF) local oscillation device having an EHF oscillator, comprising:

a first direct current cut-off device connected between an output of said EHF oscillator and an input of an amplifier;

a first low-pass filter coupled at one end thereof between said first direct current cut-off device and said amplifier and coupled to a direct current power source at the other end thereof for supplying said direct current power source to said amplifier;

a second direct current cut-off device connected between an output of said amplifier and an output of said EHF local oscillation device; and

a second low-pass filter coupled at one end thereof between said output of said amplifier and said second direct current cut-off device and coupled to a direct current supply source at the other end thereof for supplying said direct current supply source to said amplifier;

wherein said first and second direct current cut-off devices are composed of parallel resonators having a cut-off frequency matching an intermediate frequency band frequency of a device in which said EHF local oscillation device is provided;

said parasitic signal suppression circuit suppressing a parasitic signal at the output of said EHF oscillator from being transmitted to said output of the EHF local oscillation device and simultaneously passing a desired main signal to said output of said EHF local oscillation device.

2. A parasitic signal suppression circuit for an extremely high frequency (EHF) local oscillation device having an EHF oscillator, comprising:

a first direct current cut-off device connected between an output of said EHF oscillator and an input of an amplifier;

a first low-pass filter coupled at one end thereof between said first direct current cut-off device and said amplifier and coupled to a direct current power source at the other end thereof for supplying said direct current power source to said amplifier;

a second direct current cut-off device connected between an output of said amplifier and an output of said EHF local oscillation device; and

a second low-pass filter coupled at one end thereof between said output of said amplifier and said second direct current cut-off device and coupled to a direct current supply source at the other end thereof for supplying said direct current supply source to said amplifier;

said parasitic signal suppression circuit suppressing a parasitic signal at the output of said EHF oscillator from being transmitted to said output of the EHF local oscillation device and simultaneously passing a desired main signal to said output of said EHF local oscillation device;

wherein a pass band of said first and second low-pass filters matches a frequency band of said parasitic signal.

3. A parasitic signal suppression circuit for an extremely high frequency (EHF) local oscillation device having an EHF oscillator, comprising:

a first direct current cut-off device connected between an output of said EHF oscillator and an input of an amplifier;

a first low-pass filter coupled at one end thereof between said first direct current cut-off device and said amplifier and coupled to a direct current power source at the other end thereof for supplying said direct current power source to said amplifier;

a second direct current cut-off device connected between an output of said amplifier and an output of said EHF local oscillation device; and

a second low-pass filter coupled at one end thereof between said output of said amplifier and said second direct current cut-off device and coupled to a direct current supply source at the other end thereof for supplying said direct current supply source to said amplifier;

wherein said first and second direct current cut-off devices as well as said first and second low-pass filters are composed of microstrip lines, and said parasitic signal suppression circuit suppressing a parasitic signal at the output of said EHF oscillator from being transmitted to said output of the EHF local oscillation device and simultaneously passing a desired main signal to said output of said EHF local oscillation device.