KR940001596A - Intermediate frequency circuit for cell transceiver using surface acoustic wave filter - Google Patents

Abstract

An intermediate frequency circuit suitable for use in a cell telephone transceiver includes a first mixer circuit for receiving a high frequency signal and a first local oscillator signal and generating a first signal. The first signal is amplified by the first amplifier to generate the amplified second signal. The first impedance matching circuit receives the second signal and matches it to the first impedance. The Dubol mode resonator surface acoustic bandpass filter having a bandwidth of about 30 [Hz] and a noise figure of 5 dBm or less generates a filtered third signal in response to the second signal. The second impedance matching circuit receives a third signal after filtering by the double mode resonator surface acoustic bandpass filter and impedance-matches it to the second impedance. The second amplifier receives and amplifies the third signal. The second mixer circuit receives the fourth signal and the second local oscillator signal and generates an intermediate frequency signal.

Description

Intermediate frequency circuit for cell transceiver using surface acoustic wave filter

Since this is an open matter, no full text was included.

2 is a detailed block diagram of a receiver included in the block diagram of FIG.

3 is a detailed circuit diagram of the receiver circuit of FIG.

4 is a diagram for explaining a dual mode SAW resonator.

Claims (9)

A first mixer circuit for receiving a high frequency signal from a low noise input amplifier and a low first local oscillator signal from the first local oscillator circuit and generating a first signal in response thereto; A first amplifier for receiving the first signal and generating an amplified second signal, a first impedance matching circuit connected to receive the second signal and match the second signal with a first impedance; A double mode resonator surface acoustic wave pass filter for generating a filtered third signal by receiving the second signal having a bandwidth of 30 [kHz], and connected to receive the third signal; A second impedance matching circuit for matching it to a second input impedance after being filtered by a bandpass filter, and a second for receiving the third signal and generating a fourth signal in response thereto after impedance matching is performed An amplifier, a second mixer circuit for receiving the fourth signal and the second local oscillator signal and generating an intermediate frequency signal in response to the fourth signal and the second local oscillator signal, and the intermediate frequency signal; A first intermediate frequency filter connected to receive and filter a signal; a third amplifier configured to receive the intermediate frequency signal and generate an amplified intermediate frequency signal; and generate an audio frequency output signal in response to the amplified intermediate frequency signal. 11. An intermediate frequency circuit for a cell telephone receiver comprising a detector circuit coupled to each other. The cell phone receiver of claim 1, wherein the third amplifier includes a limiting amplifier circuit and one input terminal connected to receive the amplified intermediate frequency signal to limit the amplified intermediate frequency signal. Medium frequency circuit. 3. The intermediate frequency circuit of claim 2, comprising a buffer having input terminals coupled to receive an audio frequency output signal generated by the detector circuit to generate an amplified audio output signal. 4. The intermediate frequency circuit of claim 3, wherein the output terminal of the first stage of the third amplifier includes a second intermediate frequency filter connected to an input of the limiting amplifier. 5. The intermediate frequency circuit of claim 4, wherein the first local oscillator signal has a frequency of 785.84-810.84 [MHz]. 6. The intermediate frequency circuit for a receiver of a cell telephone according to claim 5, wherein said second local oscillator signal generates a frequency of 82.705 [MHz]. 7. The intermediate frequency circuit of claim 6, wherein the input amplifier has a noise figure of 2db or less. 8. The intermediate frequency circuit for a receiver of a cell phone according to claim 7, wherein the noise index of the surface acoustic wave band pass filter of the double mode resonator is 5 db or less. Applying a high frequency signal having a signal strength of -116 dbm to -40 dbm to an input amplifier, and applying an output signal generated by the first amplifier and a first local oscillator signal to a first mixer circuit to generate a first signal Generating a second signal amplified by applying the first signal, impedance matching the first impedance to the second signal, and having a bandwidth of 30 [mW] and an insertion loss of 5 db or less. Generating a filtered third signal by filtering the second signal with a mode resonator surface acoustic wave band pass filter, and after the third signal is filtered by the double mode resonator surface acoustic wave band pass filter, Impedance matching to a second impedance, amplifying the third signal after the impedance matching to generate a fourth signal, and introducing the fourth signal and the second local oscillator signal into a second mixer circuit. Generating an intermediate frequency signal, filtering the intermediate frequency signal by a first intermediate frequency filter connected to receive and filter the intermediate frequency signal, and amplifying the intermediate frequency signal to generate an amplified intermediate frequency signal. And amplifying the amplified intermediate frequency signal to a quadrature detector circuit to generate an audio frequency output signal. ※ Note: The disclosure is based on the initial application.