Receiver for mobile communication systems

• US 4,776,039 A
• Filed: 01/27/1986
• Issued: 10/04/1988
• Est. Priority Date: 01/25/1985
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Akaiwa, Yoshihiko
• Primary Examiner(s): Masinick, Michael A.
• Application Number:
  US06/822,553
• Time in Patent Office: 981 Days
• Field of Search: 455/205, 455/207-209, 455/302, 455/260, 455/315-317, 375/77, 375/97, 329/124
• US Class Current: 455/205
• CPC Class Codes: H03D 3/007 by converting the oscillations into two quadrature related signals H03D3/245 takes precedence
• CPC Class Codes: H03D 7/161 all the frequency changers being connected in cascade
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002

Abstract

A receiver suitable for use at very high frequency bands in which an antenna output is filtered, amplified and then mixed with a local oscillator in a frequency convertor to provide an intermediate frequency. The intermediate frequency is provided to a quadrature detector which directly converts the intermediate frequency into two baseband signals whose phases differ by 90°. The baseband signals are independently amplified and demodulated in a common demodulator which provides a single output signal.

Claims

1. A receiver for mobile communication systems comprising:

means for receiving a signal modulated by an original signal;

first filter means for band-limiting said received signal;

a frequency converter means having a single stage, including a frequency mixer and a band-pass filter, for converting the output signal of said first filter means into an intermediate frequency signal;

detector means for quadrature-detecting said intermediate frequency signal with a local oscillator signal whose frequency is substantially equal to the center frequency of said intermediate frequency signal and thereby providing two baseband signals;

first and second channel filter means for band-limiting each of said two baseband signals; and

demodulator means for demodulating the output signals of said first and second channel filter means into said original signal.