KR19980054198U - 900MHz wireless telephone receiver module - Google Patents

Abstract

The present invention relates to a 900MHz radiotelephone receiver module, comprising: mixing a high frequency signal induced from an antenna and an oscillation frequency of a local oscillator controlled by a phase comparison signal of a phase-locked loop linked to an oscillation frequency of a crystal oscillator; A first mixing unit for outputting a frequency, a second mixing unit for outputting a second intermediate frequency by mixing an oscillation frequency of the crystal oscillator and a first intermediate frequency of the first mixing unit, and a second intermediate unit of the second mixing unit A 900MHz radiotelephone receiver module comprising an FM demodulator for demodulating a frequency and outputting an AUDIO signal, the 900MHz wireless telephone receiver module comprising: a low pass filter configured to pass only a low frequency band of an oscillation frequency of the crystal oscillator and to be applied to the second mixing unit; Since no unwanted signal is generated, the FM demodulator outputs a good quality audio signal. There can be a very effective and at the same time to implement the miniaturization of products to help.

Description

900MHz wireless telephone receiver module

The present invention relates to a 900MHz radiotelephone receiver module, wherein an unnecessary band signal and noise included in an oscillation frequency of a crystal oscillator supplied to a second mixing unit converting a first intermediate frequency of a first mixing unit into a second intermediate frequency. The present invention relates to a 900MHz wireless telephone receiver module capable of removing components and outputting high quality audio signals.

Referring to Figure 1, a 900MHz wireless telephone receiver module which is generally used is as follows.

1 is a block diagram showing a 900MHz wireless telephone receiver module according to the prior art.

As shown in FIG. 1, the 900MHz radiotelephone receiver module according to the related art includes a first bandpass filter 11 which removes noise components included in an induced high frequency signal from an antenna ANT, and the first band. A low noise amplifier 20 for low noise amplifying the high frequency signal filtered through the pass filter 11 and a phase interlocked with the oscillation frequency of the high frequency signal and the crystal oscillator 80 low noise amplified through the low noise amplifier 20. A first mixing unit 30 for mixing the oscillation frequencies of the local oscillator 70 controlled by the phase comparison signal of the synchronization loop 60 to output a first intermediate frequency IF1, and the first mixing unit 30. A second band pass filter 12 for filtering the first intermediate frequency IF1 of the oscillator, and an oscillation frequency of the crystal oscillator 80 multiplied by a plurality of times through the divider 90 and the second band pass filter. Phase filtered through 12 A second mixing unit 40 for mixing the first intermediate frequency IF1 to output a second intermediate frequency IF2, and a third filtering second intermediate frequency IF2 of the second mixing unit 40. And a band pass filter 13 and an FM demodulator 50 for demodulating the second intermediate frequency IF2 filtered through the third band pass filter 13 and outputting an AUDIO signal.

In this case, the crystal oscillator 80 and the collector 90 will be described with reference to FIG.

Figure 2 is a circuit diagram showing a crystal oscillator and a collector applied to the 900MHz wireless telephone receiver module according to the prior art.

First, the crystal oscillator 80 applied to the 900MHz radiotelephone receiver module according to the prior art has a phase synchronization loop 60 of oscillating frequency through a first resistor R1 that performs a buffer function, as shown in FIG. A grounded fourth capacitor C4 and a fifth capacitor C5 connected in parallel to both ends of the crystal oscillator X-tal and the crystal oscillator X-tal, respectively, to adjust the oscillation frequency. The oscillation frequency of the six variable capacitor C6 and the crystal oscillator X-tal is a second resistor R2 that performs a buffer function to be outputted to the distributor 90 through a third coupling capacitor C3. Is done.

On the other hand, the distributor 90 is biased by the third resistor (R3) and the fourth resistor (R4) the oscillation frequency of the crystal oscillator (X-tal) applied through the third coupling capacitor (C3) The transistor Tr multiplies and multiplies the signal by a plurality of times, and the oscillation frequency amplified and multiplied by the transistor Tr is applied through the first coupling capacitor C1 to remove the trapping signal, thereby removing the seventh coupling capacitor C7. It consists of a resonator 91 is applied to the second mixing portion 40 through.

In this case, the resonator 91 includes a second resonant capacitor C2 and a resonant inductor L1 connected in parallel to each other between the first coupling capacitor C1 and the second coupling capacitor C7.

Referring to Figure 3 describes the operation of the 900MHz wireless telephone receiver module according to the prior art having the above configuration.

Figure 3 shows the oscillation frequency characteristics of the collector portion applied to the 900MHz wireless telephone receiver module according to the prior art, (A) is a graph showing the oscillation frequency characteristics before the passage of the collector, (B) is the passage of the collector It is a graph which shows the oscillation frequency characteristic after.

First, the high frequency signal induced from the antenna ANT from which the noise component is removed through the first band pass filter 11 is low noise amplified by the low noise amplifier 20 and applied to the first mixing unit 30.

In this case, the first mixing unit 30 is controlled by the phase comparison signal of the phase-locked loop 60 that is linked to the oscillation frequency of the crystal oscillator and the high frequency signal low noise amplified by the low noise amplifier 20 The oscillation frequency of about 0 dB of the local oscillator 70 is mixed to output the first intermediate frequency IF1 to the second band pass filter 12, and then filtered through the second band pass filter 12. The first intermediate frequency IF1 is mixed in the second mixing unit 40 and mixed with an oscillation frequency of about -15 dB of the crystal oscillator 80 multiplied by the collecting unit 90 to be 455 kHz or 4590. Is converted to the second intermediate frequency IF2 of kHz.

Here, the crystal oscillator 80 outputs an oscillation frequency of about -40 dB, as shown in FIG. 3A, and the -40 dB oscillation frequency is transmitted through the third coupling capacitor C. FIG. As shown in (b) of FIG. 3, the amplification and multiplexing is performed at the oscillation frequency of about -15 dB and output to the second mixing unit 40.

Thereafter, the second intermediate frequency IF2 is filtered through the third band pass filter 13 in the 450 kHz band and finally output as an AUDIO signal by the FM demodulator 50.

However, the 900MHz wireless telephone receiver module according to the prior art converts the first intermediate frequency IF1 of the first mixing unit 30 applied through the second band pass filter 12 into the second intermediate frequency IF2. The oscillation frequency of about -40dB of the crystal oscillator 80 supplied to the second mixing unit 40 to be amplified and collected at the oscillation frequency of about -15dB by the distributor 90 is shown in FIG. As shown, unwanted oscillation frequencies 1fosc, 3fosc, 4fosc, and the like are mixed together, resulting in an undesired signal, thereby degrading the detection function of the FM demodulator 50.

In addition, there is a problem in that the space for constituting the drainage portion 90 is required to increase the configuration of the product to act as a deterrent to the miniaturization of the product.

Accordingly, the present invention has been made to solve the above problems, and its purpose is to apply the oscillation frequency of the crystal oscillator in which unnecessary signals and noise components are removed by a low pass filter to the second mixing portion. An object of the present invention is to provide a 900MHz wireless telephone receiver module which can obtain a good audio signal through a second intermediate frequency from which noise components are removed.

1 is a block diagram showing a 900MHz wireless telephone receiver module according to the prior art

Figure 2 is a circuit diagram showing a crystal oscillator and a collector applied to the 900MHz wireless telephone receiver module according to the prior art

Figure 3 shows the oscillation frequency characteristics of the distributor applied to the 900MHz wireless telephone receiver module according to the prior art,

(A) is a graph showing the oscillation frequency characteristics before passing the collecting part,

(B) is a graph showing the oscillation frequency characteristics after passing the collecting part.

Figure 4 is a block diagram including a circuit diagram showing a 900MHz wireless telephone receiver module according to the present invention

Figure 5 is a graph showing the oscillation frequency characteristics after the low pass filter applied to the 900MHz wireless telephone receiver module according to the present invention

* Description of the symbols for the main parts of the drawings *

11: first band pass filter 12: second band pass filter

13: third band pass filter 20: low noise amplifier

30: first mixing unit 40: second mixing unit

50: FM demodulator 60: phase locked loop

70: local oscillator 80: crystal oscillator

100: low pass filter ANT: antenna

C1: first capacitor C2: second capacitor

C3: third coupling capacitor C4: fourth capacitor

C5: fifth capacitor C6: sixth variable capacitor

C7: 7th coupling capacitor IF1: 1st intermediate frequency

IF2: second intermediate frequency L1: first inductor

L2: second inductor R1: first resistor

R2: 2nd resistance X-tal: Crystal oscillator

The 900MHz radiotelephone receiver module according to the present invention for achieving the above object, the oscillation frequency of the local oscillator controlled by the phase comparison signal of the phase synchronization loop interlocked with the oscillation frequency of the crystal oscillator and the high frequency signal induced from the antenna A first mixing unit for outputting a first intermediate frequency, a second mixing unit for outputting a second intermediate frequency by mixing an oscillation frequency of the crystal oscillator and a first intermediate frequency of the first mixing unit, and the second mixing unit A 900MHz radiotelephone receiver module comprising an FM demodulator for demodulating a negative second intermediate frequency and outputting the audio signal as an AUDIO signal, comprising: a low pass applied only to a low frequency band of an oscillation frequency of the crystal oscillator and applied to the second mixed part; It includes a filter.

In addition to the above configuration, the low pass filter may include a first inductor and a second inductor sequentially connected to the crystal oscillator, a first capacitor connected in parallel between the first inductor and the second inductor, and the first capacitor. It is preferable to include a second capacitor connected in parallel between the two inductors and the second mixing portion and grounded.

Hereinafter, a preferred embodiment of a 900MHz wireless telephone receiver module according to the present invention will be described with reference to FIG.

Figure 4 is a block diagram including a circuit showing a 900MHz wireless telephone receiver module according to the present invention, the same name and the same reference numerals will be used for the configuration having the same operation as the conventional configuration.

The 900MHz radiotelephone receiver module according to the present invention, as shown in Figure 4, the high frequency filtered through the first bandpass filter 11 to remove the noise component contained in the high frequency signal induced from the antenna (ANT) A low noise amplifier 20 for low noise amplifying a signal, and a phase comparison signal of a phase-locked loop 60 that is linked to the oscillation frequency of the crystal oscillator 80 and the high frequency signal low noise amplified by the low noise amplifier 20. Filtering the first mixing unit 30 for mixing the oscillation frequency of the controlled local oscillator 70 and outputting the first intermediate frequency IF1 and the first intermediate frequency IF1 of the first mixing unit 30. The second band pass filter 12, the low pass filter 100 that passes only the low frequency band of the oscillation frequency of the crystal oscillator 80, and the crystal oscillator 80 filtered by the low pass filter 100 Of) A second mixing unit 40 for mixing an oscillation frequency and the first intermediate frequency IF1 filtered through the second band pass filter 12 to output a second intermediate frequency IF2, and the second mixing unit 40; A third band pass filter 13 for filtering the second intermediate frequency IF2 of the unit 40, and the second intermediate frequency IF2 filtered through the third band pass filter 13 to demodulate the audio. FM demodulator 50 for outputting a signal.

At this time, the crystal oscillator 80, the crystal oscillator (X-tal) for providing the oscillation frequency to the phase synchronization loop 60 through the first resistor (R1) performing a buffer function, and the crystal oscillator (X-) oscillation of the grounded fourth capacitor C4 and fifth capacitor C5 and the sixth variable capacitor C6 and the crystal oscillator X-tal, respectively connected in parallel to both ends of the tal to adjust the oscillation frequency A second resistor R2 performs a buffer function so that a frequency is applied to the low pass filter 100 through a third coupling capacitor C3.

Meanwhile, the low pass filter 100 includes a first inductor L1 and a second inductor L2 and a first inductor L1 and a second inductor L2 that are sequentially connected to the crystal oscillator 80. A second grounded parallel connection between the first capacitor C1 connected in parallel and grounded between the first capacitor C1 and a seventh coupling capacitor C7 coupled to the second inductor L2 and the second mixing unit 40. It consists of a capacitor C2.

Referring to Figure 5 the operation of the 900MHz wireless telephone receiver module according to the present invention made of the above configuration as follows.

5 is a graph showing the oscillation frequency characteristics after passing the low pass filter applied to the 900MHz wireless telephone receiver module according to the present invention.

First, the high frequency signal induced from the antenna ANT from which the noise component is removed through the first band pass filter 11 is low noise amplified by the low noise amplifier 20 and applied to the first mixing unit 30.

In this case, the first mixing unit 30 is controlled by the phase comparison signal of the phase-locked loop 60 that is linked to the oscillation frequency of the crystal oscillator and the high frequency signal low noise amplified by the low noise amplifier 20 The oscillation frequency of about 0 dB of the local oscillator 70 is mixed to output the first intermediate frequency IF1 to the second band pass filter 12, and then filtered through the second band pass filter 12. The first intermediate frequency IF1 is mixed with the oscillation frequency of the crystal oscillator 80 filtered through the low pass filter 100 by the second mixing unit 40 and converted into a second intermediate frequency IF2. .

Here, the oscillation frequency of the crystal oscillator 80 is attenuated by the low pass filter 100 at an oscillation frequency of about -40 dB, as shown in FIG. 5, and the second mixing unit through the seventh coupling capacitor C7. 40 is applied.

Thereafter, the second intermediate frequency IF2 output from the second mixing unit 40 is filtered through the third band pass filter 13 in the 450 kHz band to be finally converted into an AUDIO signal by the FM demodulator 50. Is the output.

On the other hand, when the crystal oscillator (X-tal) used in the crystal oscillator 80 uses another crystal oscillator (X-tal) that generates an oscillation frequency of about half of the output signal by the conventional distributor 90 You can also output a more stable AUDIO signal.

As described above, according to the 900MHz radiotelephone receiver module according to the present invention, the first intermediate frequency IF1 of the first mixing unit 30 applied through the second bandpass filter 12 is converted into a second intermediate frequency ( When the oscillation frequency of the crystal oscillator 80 supplied to the second mixing unit 40 converted to IF2) is removed by the low pass filter 100, signals and noise components of an unnecessary band are removed, as shown in FIG. Since only the oscillation frequency is applied to the second mixing section 40, an unwanted wave signal is not generated, so that the FM demodulation section 50 can output a high quality AUDIO signal.

In addition, there is no need for a separate space for constituting the drainage portion 90, there is a useful effect that the configuration of the product can be miniaturized.

Claims (2)

A first mixing unit for mixing an oscillation frequency of a local oscillator controlled by a phase comparison signal of a phase locked loop interlocked with an oscillation frequency of a crystal oscillator and a high frequency signal induced from an antenna and outputting a first intermediate frequency; A second mixing unit for mixing the oscillation frequency of the first mixing unit and the first intermediate frequency of the first mixing unit to output a second intermediate frequency, and an FM demodulation unit for demodulating the second intermediate frequency of the second mixing unit as an AUDIO signal. In the 900MHz radiotelephone receiver module, And a low pass filter passing through only the low frequency band of the oscillation frequency of the crystal oscillator and applied to the second mixing unit. The method of claim 1, The low pass filter may include a first inductor and a second inductor sequentially connected to the crystal oscillator, a first capacitor connected in parallel between the first inductor and the second inductor, and the second inductor and the second inductor. 900MHz wireless telephone receiver module, characterized in that it comprises a second capacitor grounded connected in parallel between the mixing section.