KR100311822B1 - Automatic gain control circuit of cordless phone - Google Patents
Automatic gain control circuit of cordless phone Download PDFInfo
- Publication number
- KR100311822B1 KR100311822B1 KR1019990058207A KR19990058207A KR100311822B1 KR 100311822 B1 KR100311822 B1 KR 100311822B1 KR 1019990058207 A KR1019990058207 A KR 1019990058207A KR 19990058207 A KR19990058207 A KR 19990058207A KR 100311822 B1 KR100311822 B1 KR 100311822B1
- Authority
- KR
- South Korea
- Prior art keywords
- low noise
- signal
- control circuit
- gain control
- automatic gain
- Prior art date
Links
- 230000010355 oscillation Effects 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims 1
- 230000005684 electric field Effects 0.000 abstract description 10
- 238000005336 cracking Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 230000005236 sound signal Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/72—Mobile telephones; Cordless telephones, i.e. devices for establishing wireless links to base stations without route selection
- H04M1/725—Cordless telephones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M2201/00—Electronic components, circuits, software, systems or apparatus used in telephone systems
- H04M2201/04—Transistors
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M2201/00—Electronic components, circuits, software, systems or apparatus used in telephone systems
- H04M2201/06—Integrated circuits
Abstract
본 발명은 코드레스 전화기의 자동이득조절회로에 관한 것으로, 본 발명은 안테나(ant)를 통해 입력되는 신호를 필터링하는 필터(21)와, 이 필터(21)의 출력신호를 저잡음으로 증폭하는 저잡음증폭기(22)와, 이 저잡음증폭기(22)의 출력신호와 내부 발진주파수를 믹싱하여 중간주파신호를 제공하는 PLL IC(23)와, 이 PLL IC(23)의 출력신호를 복조하는 IF복조부(26)를 포함하는 코드레스 전화기의 자동이득조절회로에 있어서, IF복조부(26)의 신호강도지시신호(RSSI)의 레벨에 따라 스위칭동작하는 스위칭소자를 구비하고, 이 스위칭 소자의 스위칭동작에 따라 바이어스저항을 가변시켜 저잡음증폭기(22)의 이득을 조절하는 자동이득조절회로(27);을 구비하여, 전압제어발진기와 믹서를 포함하는 위상동기루프(PLL) IC에서 강전계 입력시 데이타가 깨지는 현상을 방지할 수 있다.The present invention relates to an automatic gain control circuit of a cordless telephone. The present invention relates to a filter 21 for filtering a signal input through an antenna and a low noise for amplifying the output signal of the filter 21 with low noise. An amplifier 22, a PLL IC 23 for mixing the output signal of the low noise amplifier 22 with an internal oscillation frequency to provide an intermediate frequency signal, and an IF demodulator for demodulating the output signal of the PLL IC 23; An automatic gain control circuit of a cordless telephone comprising: (26), comprising: a switching element for switching in accordance with the level of the signal strength instruction signal (RSSI) of the IF demodulation unit (26); An automatic gain control circuit 27 that adjusts the gain of the low noise amplifier 22 by varying the bias resistance according to the data, and includes a voltage-controlled oscillator and a mixer for inputting a strong electric field in a phase locked loop (PLL) IC. To prevent cracking There.
Description
본 발명은 코드레스 전화기의 자동이득조절회로에 관한 것으로, 특히 전압제어발진기와 믹서를 포함하는 위상동기루프(PLL) IC에서 강전계 입력시 데이타가 깨지는 현상을 방지하도록 하는 코드레스 전화기의 자동이득조절회로에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic gain control circuit of a cordless telephone. In particular, the automatic gain of a cordless telephone to prevent data from being broken upon input of a strong field in a phase locked loop (PLL) IC including a voltage controlled oscillator and a mixer. It relates to a control circuit.
일반적으로, 코드레스 전화기는 전압제어발진기(VCO)와, 중간주파(IF)신호를 출력하는 믹서가 포함된 PLL IC를 사용하고 있다.In general, cordless telephones use a PLL IC including a voltage controlled oscillator (VCO) and a mixer for outputting an intermediate frequency (IF) signal.
도 1은 종래의 코드레스 전화기의 내부회로도로서, 도 1을 참조하면, 종래의 코드레스 전화기는 안테나(ant)를 통해 수신된 저잡음 증폭기(11)에서 저잡음으로 증폭한후 PLL IC(12)로 제공하는데, 이때, PLL IC(12)는 내부 전압제어발진기의 발진주파수와 입력신호를 믹싱하여 IF복조부(14)로 제공한다.FIG. 1 is an internal circuit diagram of a conventional cordless telephone. Referring to FIG. 1, a conventional cordless telephone is amplified to low noise by a low noise amplifier 11 received through an antenna ant and then transferred to a PLL IC 12. In this case, the PLL IC 12 mixes the oscillation frequency and the input signal of the internal voltage controlled oscillator and provides it to the IF demodulator 14.
이와같이, PLL IC(12)에 내장된 전압제어발진기(VCO)를 사용하는 관계로, 안테나로부터 강전계 입력시 수신 전압제어발진기의 풀링(pulling)특성이 나빠져서 전압제어발진기(VCO)의 발진주파수가 흔들리는 현상이 발생되고, 이에따라 수신 오디오신호 복조시, 오디오신호가 깨지는 현상이 발생되는 현상이 발생하는 문제점이 있었던 것이다. 또한 이로 인하여 다이내믹 레인지가 줄어드는 문제점이 있었던 것이다.In this way, since the voltage controlled oscillator (VCO) built in the PLL IC 12 is used, the pulling characteristic of the received voltage controlled oscillator deteriorates when a strong electric field is input from the antenna, so that the oscillation frequency of the voltage controlled oscillator (VCO) is increased. The shaking phenomenon occurs, and accordingly, when the received audio signal is demodulated, a phenomenon in which the audio signal is broken occurs. In addition, there was a problem that the dynamic range is reduced by this.
본 발명은 상기한 문제점을 해결하기 위해 안출한 것으로, 따라서, 본 발명의 목적은 전압제어발진기와 믹서를 포함하는 위상동기루프(PLL) IC에서 강전계 입력시 데이타가 깨지는 현상을 방지하도록 하는 코드레스 전화기의 자동이득조절회로를 제공하는데 있다.SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide a code for preventing data from being broken when inputting a strong electric field in a phase locked loop (PLL) IC including a voltage controlled oscillator and a mixer. An automatic gain control circuit for a telephone is provided.
도 1은 종래의 코드레스 전화기의 내부회로도이다.1 is an internal circuit diagram of a conventional cordless telephone.
도 2는 본 발명에 따른 코드레스 전화기의 자동이득조절회로도이다.2 is an automatic gain control circuit diagram of a cordless telephone according to the present invention.
* 도면의 주요부분에 대한 부호의 설명 *Explanation of symbols on the main parts of the drawings
21 : 필터 22 : 저잡음증폭기21 filter 22 low noise amplifier
23 : PLL IC 24 : 증폭기23: PLL IC 24: Amplifier
25 : 필터 26 : IF복조부25 filter 26 IF demodulation unit
27 : 자동이득조절회로27: automatic gain control circuit
상기한 본 발명의 목적을 달성하기 위한 기술적인 수단으로써, 본 발명의 회로는 안테나(ant)를 통해 입력되는 신호를 필터링하는 필터와, 이 필터의 출력신호를 저잡음으로 증폭하는 저잡음증폭기와, 이 저잡음증폭기의 출력신호와 내부 발진주파수를 믹싱하여 중간주파신호를 제공하는 PLL IC와, 이 PLL IC의 출력신호를 복조하는 IF복조부를 포함하는 코드레스 전화기의 자동이득조절회로에 있어서, IF복조부의 신호강도지시신호(RSSI)의 레벨에 따라 스위칭동작하는 스위칭소자를 구비하고, 이 스위칭 소자의 스위칭동작에 따라 바이어스저항을 가변시켜 저잡음증폭기의 이득을 조절하는 자동이득조절회로;을 구비함을 특징으로 한다.As a technical means for achieving the above object of the present invention, the circuit of the present invention includes a filter for filtering a signal input through an antenna (ant), a low noise amplifier for amplifying the output signal of the filter with a low noise, In the automatic gain control circuit of a cordless telephone, the PLL IC comprising an intermediate frequency signal by mixing an output signal and an internal oscillation frequency of a low noise amplifier and an IF demodulation section that demodulates the output signal of the PLL IC. And a switching element for switching according to the level of the signal strength indicating signal (RSSI), and an automatic gain control circuit for controlling the gain of the low noise amplifier by varying the bias resistance according to the switching operation of the switching element. It is done.
이하, 본 발명에 따른 코드레스 전화기의 자동이득조절회로에 대해서 첨부한 도면을 참조하여 상세하게 설명한다.Hereinafter, the automatic gain control circuit of the cordless telephone according to the present invention will be described in detail with reference to the accompanying drawings.
도 2는 본 발명에 따른 코드레스 전화기의 자동이득조절회로도로서, 도 2를 참조하면, 본 발명에 따른 코드레스 전화기의 자동이득조절회로는 안테나(ant)를 통해 입력되는 신호를 필터링하는 필터(21)와, 이 필터(21)의 출력신호를 저잡음으로 증폭하는 저잡음증폭기(22)와, 이 저잡음증폭기(22)의 출력신호와 내부 발진주파수를 믹싱하여 중간주파신호를 제공하는 PLL IC(23)와, 이 PLL IC(23)의 출력신호를 복조하는 IF복조부(26)를 포함하는 코드레스 전화기에 포함된다.2 is an automatic gain control circuit diagram of a cordless telephone according to the present invention. Referring to FIG. 2, the automatic gain control circuit of the cordless telephone according to the present invention is a filter for filtering a signal input through an antenna (ant). 21, a low noise amplifier 22 for amplifying the output signal of the filter 21 with low noise, and a PLL IC 23 for mixing the output signal of the low noise amplifier 22 with an internal oscillation frequency to provide an intermediate frequency signal. ) And an IF demodulation section 26 for demodulating the output signal of the PLL IC 23.
상기 자동이득조절회로(27)는 IF복조부(26)의 신호강도지시신호(RSSI)의 레벨에 따라 스위칭동작하는 스위칭소자를 구비하고, 이 스위칭 소자의 스위칭동작에 따라 바이어스저항을 가변시켜 저잡음증폭기(22)의 이득을 조절하도록 구성한다.The automatic gain control circuit 27 includes a switching element that switches according to the level of the signal strength indication signal RSSI of the IF demodulator 26, and varies the bias resistance according to the switching operation of the switching element to lower noise. It is configured to adjust the gain of the amplifier 22.
상기 자동이득조절회로(27)의 구체적인 회로는 IF복조부(26)의 신호강도지시신호(RSSI)에 베이스단을 접속하고, 제2저항(R2)을 통해서 전원전압(V2) 및 제3저항(R3)을 통해서 상기 저잡음증폭기(22)의 입력단에 에미터단을 접속하며, 제4저항(R4)을 통해서 상기 저잡음증폭기(22)의 입력단에 컬렉터단을 접속한 PNP 트랜지스터(Q2)를 포함한다.The specific circuit of the automatic gain control circuit 27 connects the base terminal to the signal strength indicating signal RSSI of the IF demodulator 26 and supplies the power supply voltage V2 and the third resistor through the second resistor R2. And a PNP transistor Q2 having an emitter terminal connected to the input terminal of the low noise amplifier 22 through R3 and a collector terminal connected to the input terminal of the low noise amplifier 22 through a fourth resistor R4. .
이와같이 구성된 본 발명의 회로에 따른 동작을 첨부도면에 의거하여 하기에 상세히 설명한다.Operation according to the circuit of the present invention configured as described above will be described in detail below based on the accompanying drawings.
도 2를 참조하여 본 발명을 설명하면, 먼저, 안테나(ant)를 통한 수신신호는 필터(21)를 통한 저잡음증폭기(21)에서 저잡음으로 증폭된후 코일(L1)과 커패시터(C3)를 통하여 PLL IC(23)로 제공된다. 이 PLL IC(23)는 입력받은 신호와 내부 동기된 발진주파수를 믹싱함에 의한 중간주파(IF)신호를 출력한다. 이 중간주파신호는 증폭기(24)에서 증폭되고, 필터(25)에서 필터링된후 IF복조부(26)에서 복조된다.Referring to FIG. 2, first, the received signal through the antenna ant is amplified to low noise in the low noise amplifier 21 through the filter 21 and then through the coil L1 and the capacitor C3. To the PLL IC 23. The PLL IC 23 outputs an intermediate frequency (IF) signal by mixing an input signal with an internally synchronized oscillation frequency. This intermediate frequency signal is amplified by the amplifier 24, filtered by the filter 25, and then demodulated by the IF demodulator 26.
상기 IF복조부(26)는 입력받은 중간주파(IF)신호에 대한 강도를 지시하는 신호강도지시신호(RSSI)를 제공하는데, 이 신호강도지시신호(RSSI)는 신호가 강전계일 경우에는 하이레벨을, 반대로 신호가 약전계일 경우에는 로우레벨을 제공한다.The IF demodulator 26 provides a signal strength indication signal (RSSI) indicating the strength of the received intermediate frequency (IF) signal, which is a high level when the signal is a strong electric field. Conversely, if the signal is a weak field, it provides a low level.
따라서, 약전계에서는 신호강도지시신호(RSSI)가 로우레벨이므로, 자동이득조절회로(27)의 스위칭소자인 트랜지스터(Q2)가 온되며, 이에따라 저잡음증폭기(22)내 트랜지스터(Q1)의 베이스-에미터간 전압(Vbe)이 두 저항(R3,R4)의 병렬 합저항과, 베이스전류(Ib)에 의해서 결정되므로, 합저항이 낮으므로 베이스전류는 크지고, 이에따라 하기 수학식1에 의하면, 콜렉터전류(Ic)가 증가하므로 이득(β)은 증가한다.Therefore, in the weak electric field, since the signal intensity indicating signal RSSI is at a low level, the transistor Q2, which is a switching element of the automatic gain control circuit 27, is turned on, and thus the base of the transistor Q1 in the low noise amplifier 22 is turned on. Since the inter-emitter voltage Vbe is determined by the parallel sum resistances of the two resistors R3 and R4 and the base current Ib, the base resistance is large because the sum resistance is low. Accordingly, according to Equation 1, the collector The gain β increases because the current Ic increases.
한편, 강전계에서는 신호강도지시신호(RSSI)가 하이레벨이므로, 자동이득조절회로(27)의 스위칭소자인 트랜지스터(Q2)가 오프되며, 이에따라 저잡음증폭기(22)내 트랜지스터(Q1)의 베이스-에미터간 전압(Vbe)이 하나의 저항(R3)과, 베이스전류(Ib)에 의해서 결정되므로, 상기한 병렬 합저항보다 상대적으로 저항이 높으므로 베이스전류는 작아지고, 이에따라 상기 수학식1에 의하면, 콜렉터전류(Ic)도 감소하므로 이득(β)은 감소한다.On the other hand, in the strong electric field, since the signal strength indicating signal RSSI is at a high level, the transistor Q2, which is a switching element of the automatic gain control circuit 27, is turned off, so that the base of the transistor Q1 in the low noise amplifier 22 is turned off. Since the emitter-to-emitter voltage Vbe is determined by one resistor R3 and the base current Ib, the resistance is relatively higher than the parallel summation resistance, so the base current becomes smaller, and according to Equation 1 Since the collector current Ic also decreases, the gain β decreases.
이와같이, 강전계에서는 이득이 작아지므로, 강전에서 신호가 깨지는 현상이 방지되며, 또한 약전계에서는 이득이 크지므로 수신감도가 향상되는 것이다.As described above, since the gain is reduced in the strong electric field, the signal breakage is prevented in the strong electric field, and the reception sensitivity is improved because the gain is large in the weak electric field.
상술한 바와같은 본 발명에 따르면, 전압제어발진기와 믹서를 포함하는 위상동기루프(PLL) IC에서 강전계 입력시 데이타가 깨지는 현상을 방지하도록 하는 특별한 효과가 있는 것이다.According to the present invention as described above, in the phase locked loop (PLL) IC including a voltage controlled oscillator and a mixer, there is a special effect of preventing data from being broken when inputting a strong electric field.
이상의 설명은 본 발명의 일실시예에 대한 설명에 불과하며, 본 발명은 그 구성의 범위내에서 다양한 변경 및 개조가 가능하다.The above description is only a description of one embodiment of the present invention, the present invention is capable of various changes and modifications within the scope of the configuration.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019990058207A KR100311822B1 (en) | 1999-12-16 | 1999-12-16 | Automatic gain control circuit of cordless phone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019990058207A KR100311822B1 (en) | 1999-12-16 | 1999-12-16 | Automatic gain control circuit of cordless phone |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| KR20010056648A KR20010056648A (en) | 2001-07-04 |
| KR100311822B1 true KR100311822B1 (en) | 2001-10-17 |
Family
ID=19626282
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| KR1019990058207A KR100311822B1 (en) | 1999-12-16 | 1999-12-16 | Automatic gain control circuit of cordless phone |
Country Status (1)
| Country | Link |
|---|---|
| KR (1) | KR100311822B1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100785003B1 (en) * | 2002-09-06 | 2007-12-11 | 삼성전자주식회사 | Multiband transceiver using control voltage of phase locked loop, and method therefor |
-
1999
- 1999-12-16 KR KR1019990058207A patent/KR100311822B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR20010056648A (en) | 2001-07-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR970072734A (en) | Automatic gain control circuit of radio receiver | |
| US6734745B2 (en) | Oscillator and communication apparatus using the same | |
| JPH10247858A (en) | Radio receiver | |
| JP4251507B2 (en) | Radio receiver and gain adjusting amplifier therefor | |
| US5436931A (en) | FSK receiver | |
| KR100393536B1 (en) | Power circuit | |
| US6288615B1 (en) | Switch-type oscillating circuit for providing isolation between first and second oscillating circuits | |
| KR100311822B1 (en) | Automatic gain control circuit of cordless phone | |
| CA1095128A (en) | Integrated front end circuit for vhf receiver | |
| JPH11506896A (en) | Wireless receiver improvements and improvements related to wireless receivers | |
| KR100212055B1 (en) | Rssi detecting circuit of mobile communication system | |
| US5994964A (en) | Gain-control-type transistor power amplifier | |
| EP1071201A2 (en) | Selectable voltage-controlled oscillation circuit | |
| US5481226A (en) | Low-voltage intermediate frequency amplifier providing automatic gain control of a source amplifier | |
| US6281757B1 (en) | High frequency signal amplifying circuit and a receiver using the same | |
| GB2250402A (en) | Power saving arrangement for a radiotelephone | |
| KR0154598B1 (en) | Strong input compensation circuit of the tuner | |
| JP3388700B2 (en) | AM radio receiver | |
| JP2004023532A (en) | Automatic gain control circuit in receiver | |
| JP3995607B2 (en) | Broadcast wave receiver | |
| EP0797304A2 (en) | Improvements in or relating to radio receivers | |
| JP2004350029A (en) | Broadcasting reception device | |
| KR940007132Y1 (en) | Receiving signal amplifying device for mobile telephone | |
| JP2003258673A (en) | Attenuator circuit for wireless transceiver | |
| JP2000091845A (en) | Colpitts oscillating circuit and radio communication terminal equipment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A201 | Request for examination | ||
| E701 | Decision to grant or registration of patent right | ||
| GRNT | Written decision to grant | ||
| LAPS | Lapse due to unpaid annual fee |