KR950001504B1 - Echo cancel circuit of radio frequency - Google Patents

Echo cancel circuit of radio frequency Download PDF

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KR950001504B1
KR950001504B1 KR1019920004428A KR920004428A KR950001504B1 KR 950001504 B1 KR950001504 B1 KR 950001504B1 KR 1019920004428 A KR1019920004428 A KR 1019920004428A KR 920004428 A KR920004428 A KR 920004428A KR 950001504 B1 KR950001504 B1 KR 950001504B1
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pll
circuit
sub
oscillation
frequency
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KR1019920004428A
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KR930020872A (en
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박찬현
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현대전자산업주식회사
김주용
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/403—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/085—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal
    • H03L7/093—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal using special filtering or amplification characteristics in the loop
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication
    • H04B1/56—Circuits using the same frequency for two directions of communication with provision for simultaneous communication in two directions

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transceivers (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)

Abstract

The circuit uses the PLL method for echo cancel, reduces the test time and the scale of circuit design, and improves the productivity. The circuit includes a sub-PLL (20) which receives the reference signal from temperature compesation oscillation (TXCO), an oscillation circuit (21), the 1st varicap (V1) which loop-locks the oscillation frequncy that is received at the 3rd passive filter (LF), and the 2nd varicap (V2) which modulates a phase shift apmlifier outout (10).

Description

무선기기의 에코캔슬 회로Eco-cancellation circuit of wireless device

제1도는 무선기기의 에코신호 발생원리도.1 is a principle diagram of echo signal generation in a wireless device.

제2도는 제1도에서의 에코캔슬 회로.2 is an echo cancel circuit in FIG.

제3a, b도는 PLL과 VCXO의 변조특성도.3A and 3B show modulation characteristics of PLL and VCXO.

제4도는 본 발명의 회로도.4 is a circuit diagram of the present invention.

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

2 : 메인 PLL 9 : 제2혼합기2: Main PLL 9: 2nd Mixer

10 : 위상쉬프트 증폭기 20 : 서브 PLL10: phase shift amplifier 20: sub PLL

21 : 발진회로 TCXO : 온도보상발진기21: oscillation circuit TCXO: temperature compensation oscillator

L : 코일 Co : 콘덴서L: Coil Co: Condenser

C1, C3, C4 : 콘덴서 R1∼R5 : 저항C1, C3, C4: capacitors R1 to R5: resistors

LF : 3차 수동루프필터LF: 3rd Passive Loop Filter

본 발명은 송수신이 동시에 행해지는 풀 듀플렉스(Full Duplex) 형태의 카폰, 핸드헬드폰(Hand Held Phone) 및 코드리스폰(Cordless Phone)등의 무선기기를 1-PLL화 하는데 필수적으로 요구되는 에코캔슬 회로에 관한 것이다.The present invention is an eco-cancellation circuit required to 1-PLL wireless devices such as full duplex type car phones, hand held phones, cordless phones, and the like, in which transmission and reception are simultaneously performed. It is about.

일반적으로 1-PLL씨스템은 제1도와 같이 변조신호(A Sinwt)를 전압제어 발진기(1) VCO에 제공하며, 전압제어발진기(1) 출력은 PLL(2)과 루프를 이루어 송신앰프(3)와 제1혼합기(4)에 공급되고, 변조신호는 송신앰프(3), 송신필터(5) 및 안테나(6)를 차례로 통해 송신되고, 안테나(6)로 수신되는 신호는 수신필터(7)를 거친 신호(C Sinω2t)가 수신앰프(8)에서 증폭되며, 이는 전압제어발진기(1)측으로부터 공급된 신호(A Sinωt+B Sinω1t)와 제1혼합기(4)에서 혼합되고, 이는 다시 발진주파수(D Sinω3t)로 수정발진기에서 발진되는 신호와 제2혼합기(9)에서 혼합 및 중간주파증폭(IF)되어 복조(Demodulated Data on Audio)하게 된다(K Cosω't(±A Sinωt)).In general, the 1-PLL system provides a modulated signal (A Sinwt) to the voltage controlled oscillator (1) VCO as shown in FIG. 1, and the output of the voltage controlled oscillator (1) is looped with the PLL (2) to transmit the amplifier (3). And a first mixer (4), the modulated signal is transmitted through the transmission amplifier (3), the transmission filter (5) and the antenna (6) in turn, and the signal received by the antenna (6) is the reception filter (7). Signal C Sinω 2 t is amplified in the receiving amplifier 8, which is mixed in the first mixer 4 with the signal A Sinωt + B Sinω 1 t supplied from the voltage controlled oscillator 1 side. In addition, it is mixed with the signal oscillated from the crystal oscillator at the oscillation frequency (D Sinω 3 t) and the second mixer 9 and the intermediate frequency amplification (IF) to demodulate the data (K Cosω't ( ± A Sinωt)).

즉, 1개의 PLL씨스템 방식으로 송신측의 주파수 합성 및 수신프론트엔드 혼합기(제1혼합기(4))의 로칼소오스(Local Source)를 겸하고 있어, PLL(2)에 정보를 전달하기 위한 변조가 행하여질 경우 변조된 신호(A Sinωt+B Sinω1t)가 그대로 제1혼합기(4)에 전달되어 변조신호(A Sinωt)로 되어 변조신호 A Sinωt가 에코신호로 나타나게 되는 것이다.That is, one PLL system combines the frequency synthesis of the transmitting side and the local source of the receiving front end mixer (the first mixer 4), and the modulation is performed to transfer information to the PLL (2). In this case, the modulated signal A Sinωt + B Sinω 1 t is transferred to the first mixer 4 as it is and becomes the modulation signal A Sinωt, so that the modulated signal A Sinωt appears as an echo signal.

구체적으로, K Cosω't=[(C Sinω2t∼(A Sinωt+B Sinω1t)]∼D Sinω3t)로 나타내어지며 역시 A Sinωt의 에코신호를 포함함을 명확히 알 수 있다. 특히 데이타 및 이동통신(Cellular System)에서의 SAT(Supervisory Audio Tone)같은 경우, 실제신호와 에코신호에 의한 위상지연이 2도를 넘게되면 단말기와 싸이트(Site)간의 접속이 단절되어 버리는 극히 치명적인 결과를 초래한다.Specifically, it can be clearly seen that K Cosω't = [(C Sinω 2 t to (A Sinωt + B Sinω 1 t)] to D Sinω 3 t) and also includes an echo signal of A Sinωt. Especially in the case of SAT (Supervisory Audio Tone) in data and cellular systems, if the phase delay caused by the actual signal and the echo signal exceeds 2 degrees, the extremely fatal result of disconnection between the terminal and the site. Results in.

따라서 이러한 에코신호를 제거하기 위한 에코캔슬 회로를 사용하고 있다. 이는, 제2도와 같이 도시할 수 있으며, 변조신호를 전압제어발진기(1)와 동시에 제공받는 위상쉬프트(Phase Shift) 증폭기(10)와 ; 위상쉬프트 증폭기(10)의 출력에 따라 공진을 변화시키는 크리스탈 발진기(x-tal), 변성코일(IFT1) 및 배리캡(Varicap)과; 변성코일(IFT2,IFT3); 발진기(11) 및 체배기(12)로 이루어지며, 3차 변성코일(IFT3)의 출력이 제2혼합기(9)에 제공되도록 이루어진다.Therefore, an echo cancel circuit is used to remove such echo signals. This, as shown in FIG. 2, may include a phase shift amplifier 10 that receives a modulated signal simultaneously with the voltage controlled oscillator 1; A crystal oscillator (x-tal), a modified coil ITF1, and a varicap that change resonance according to the output of the phase shift amplifier 10; Modified coils (IFT2, IFT3); It consists of an oscillator 11 and a multiplier 12, the output of the third modified coil (IFT3) is made to be provided to the second mixer (9).

이는 크리스탈발진기(x-tal)와 변성코일(IFT1) 및 배리캡(Varicap)을 사용하여 변조에너지에 의한 배리캡(Varicap)의 용량을 변화시켜, 결과적으로 크리스탈(x-tal)의 직렬공진 임피던스가 변화되게 함으로써, 크리스탈(x-tal) 공진주파수의 드리프트(Drift)를 발생시켜 변조가 걸린것과 같은 효과를 얻도록 한다. 그러나 크리스탈(x-tal)의 Q는 현재 일반적으로 다루어지는 모든 전자부품중에서 가장 높으며, 바꾸어 말하면 크리스탈(x-tal)을 이용한 발진기의 경우 극히 안정된 주파수를 얻을 수 있다는 것이며, 역으로 그만큼 주파수의 드리프트(즉, 변조)를 정도이상으로 얻기 힘들다는 것이다.This uses the crystal oscillator (x-tal), modified coil (IFT1) and varicap to change the capacity of the varicap due to the modulation energy, resulting in the series resonance impedance of the crystal (x-tal). By varying, a drift of the crystal (x-tal) resonant frequency is generated to obtain an effect such as modulation. However, the Q of the crystal (x-tal) is the highest of all electronic components currently handled in general, that is, in the case of an oscillator using a crystal (x-tal), an extremely stable frequency can be obtained, and vice versa. (I.e., modulation) is hard to get beyond that.

따라서 필요한 만큼의 변조도를 얻기 위해서 주파수 체배기(12)(×3 혹은 그 이상)가 필요해진다. 이는 한정된 드리프트의 양을 체배한 만큼 늘려보자는 것이다. 이 경우 주파수 체배기(12)에 의해 불필요한 고조파(Harmonics) 성분의 증대하며, 주파수 안정도 역시 체배수만큼 감소하는 단점이 있게 된다. 또한 발진주파수 세트를 위한 변성코일(IFT1), 체배를 위한 변성코일(IFT2) 및 고조파 억제용 및 단간결합용 변성코일(IFT3)등 2-PLL씨스템에 비해 최소한 3개소 이상의 조정 포인트가 늘어나므로 공간을 많이 차지할 뿐만 아니라 조정하기도 힘들게 된다.Therefore, the frequency multiplier 12 (× 3 or more) is required to obtain the required modulation degree. This is to increase the limited amount of drift by the multiplication. In this case, the frequency multiplier 12 increases unnecessary harmonics, and the frequency stability also decreases by the multiplication factor. In addition, at least three adjustment points increase compared to 2-PLL systems such as modified coil (IFT1) for oscillation frequency set, modified coil (IFT2) for multiplication, and modified coil (IFT3) for harmonic suppression and short-term coupling. Not only does it take a lot of money, but it also becomes hard to adjust.

최종적으로 가장 중요한 에코캔슬 효과를 볼때 제3도에서 나타낸 바와 같이 PLL씨스템과 에코캔슬 씨스템(VCXO; Variable Capacitance X-tal Oscillator)에서의 변조 입력레벨 별(제3a도), 변조주파수별(제3b도) 변조효과가 상이하기 때문에 실제적으로 필요한 전대역에서의 에코캔슬 효과를 원리적으로 기대할 수 없다(예를들어, 도요컴(TOYOCOM)사의 핸드헬드폰(모델명; HHP-5000)의 경우 전대역 매치가 불가능하므로 가장 중요한 SAT대역에 집중적으로 매치시켰으며 이때 에코 감쇄율은 -20dB정도이다). 즉, PLL의 루프 응답특성과 에코캔슬 씨스템(이하 VCXO라 함)의 주파수 드리프트율은 전혀 다른 함수이며 유사하지 않아 특정 주파수 대역에 집중매치시켜 사용하여야만 되는 단점이 있다.Finally, as shown in FIG. 3, the most important echo canceling effect is as shown in FIG. 3 and according to modulation input level (FIG. 3a) and modulation frequency (FIG. 3b) in PLL system and Variable Capacitance X-tal Oscillator (VCXO). Due to the different modulation effects, it is not possible to expect the principle of echo canceling effect on the entire band actually required (for example, in the case of TOYOCOM's handheld phone (model name: HHP-5000) Since this is impossible, we have concentrated on the most important SAT bands, with an echo attenuation of about -20 dB). That is, the loop response characteristic of the PLL and the frequency drift rate of the echo cancelation system (hereinafter referred to as VCXO) are completely different functions and are not similar to each other, and thus have to be concentrated and used in a specific frequency band.

따라서 본 발명은 이를 해결코자 하는 것으로, 1-PLL씨스템의 에코캔슬을 위해 코일과 콘덴서를 이용 주파수를 발진시키고 서브 PLL의 위상에러 신호를 제1배리캡으로 발진주파수를 루프록시키며, 제2배리캡으로 위상쉬프트 증폭기 신호를 받아 에코캔슬시킴을 특징으로 한다.Therefore, the present invention is to solve this problem, to oscillate the frequency using a coil and a condenser for the echo cancellation of the 1-PLL system, loop-locking the oscillation frequency with the first error cap of the phase error signal of the sub-PLL, the second The cap is used to echo cancel the phase shift amplifier signal.

즉, 메인 PLL과 동시에 기준신호를 온도보상 발진기로부터 제공받는 서브 PLL과; 제2혼합기 및 서브 PLL에 발진주파수를 제공하도록 코일과 콘덴서로 이루어지는 발진회로와; 발진회로와 접속되며 서브 PLL의 위상에러 신호를 3차 수동루프필터를 통해 주입하여 발진주파수를 루프록시키는 제1배리캡과; 제1배리캡과 병렬로 접속되고, 변조신호를 받아 쉬프트되는 위상쉬프트 증폭기 출력이 에코캔슬용 변조를 걸도록된 제2배리캡을 포함하여 구성된 것이다.That is, the sub PLL which receives the reference signal from the temperature compensation oscillator simultaneously with the main PLL; An oscillation circuit comprising a coil and a condenser to provide an oscillation frequency to the second mixer and the sub PLL; A first barrier cap connected to the oscillation circuit and loop-locking the oscillation frequency by injecting the phase error signal of the sub PLL through a third-order passive loop filter; A phase shift amplifier output connected in parallel with the first vari cap and shifted in response to a modulated signal includes a second vari cap configured to perform modulation for echo cancellation.

이하 도면을 참조하여 상세히 설명하면 다음과 같다.When described in detail with reference to the drawings as follows.

본 발명은 메인 PLL(2)과 동시에 기준신호를 온도보상 발진기(TCXO)로부터 제공받는 서브 PLL(20)과; 제2혼합기(9) 및 서브 PLL(20)에 발진주파수를 제공하도록 코일(L)과 콘덴서(Co)로 이루어진 발진회로(21)와; 발진회로(21)와 콘덴서(C1)를 통해 접속되며, 서브 PLL(20)의 위상에러 신호를 저항(R1∼R4) 및 콘덴서(C3,C4)로된 3차 수동 루프필터(LF)를 통해 주입하여 발진주파수를 루프록(Loop Lock)시키는 제1배리캡(V1)과; 제1배리캡(V1)과 병렬로 접속되고, 변조신호를 받아 쉬프트되는 위상쉬프트 증폭기(10) 출력이 저항(R5)을 통해 에코캔슬용 변조를 거는 제2배리캡(V2)을 포함하여 구성된다.The present invention provides a sub-PLL (20) for receiving a reference signal from a temperature compensation oscillator (TCXO) simultaneously with the main PLL (2); An oscillation circuit 21 composed of a coil L and a condenser Co so as to provide an oscillation frequency to the second mixer 9 and the sub PLL 20; The phase error signal of the sub PLL 20 is connected to the oscillation circuit 21 and the capacitor C1 through a third-order passive loop filter LF consisting of resistors R1 to R4 and capacitors C3 and C4. A first barrier cap V1 injected to loop the oscillation frequency; The output of the phase shift amplifier 10 connected in parallel with the first vari cap V1 and shifted in response to a modulation signal includes a second vari cap V2 for performing echo cancellation modulation through the resistor R5. do.

본 발명에서의 온도보상 발진기(TCXO; Temperature Compensated X-tal Oscillator)는 주파수 안정도가 ±2PPM이하가 바람직하다.Temperature Compensated X-tal Oscillator (TCXO) in the present invention preferably has a frequency stability of ± 2PPM or less.

본 발명에서의 위상쉬프트 증폭기(10)는 변조신호(Modulation; A Sinωt)를 받아 위상을 180도 쉬프트 시키는 회로로써, 제2도에서의 증폭기(10)로 나타낸 것과 같은 일반적인 회로이므로 상세한 설명은 생략한다. 본 발명에서의 PLL(2,20)은 클럭(CK)과 데이타(DATA)를 동시에 제공받아 구동되도록 설계된다.The phase shift amplifier 10 according to the present invention receives a modulated signal (A Sinωt) and shifts the phase by 180 degrees. Since the phase shift amplifier 10 is a general circuit as shown by the amplifier 10 in FIG. do. In the present invention, the PLLs 2 and 20 are designed to be driven by receiving the clock CK and the data DATA at the same time.

본 발명에서의 발진회로(21)는 콘덴서(C7)를 통해 서브 PLL(20)에 피드백되며, 콘덴서(C5,C6) 및 저항(R6)은 리플방지용, 콘덴서(C2)는 제2배리캡(V2)매칭용이다. (9',9＂)는 제2혼합기(9)의 필터이고, (4')는 제1혼합기(4) 신호를 제2혼합기(9)에 제공하기 위한 필터이다.In the present invention, the oscillation circuit 21 is fed back to the sub PLL 20 through the capacitor C7, the capacitors C5 and C6 and the resistor R6 are for preventing the ripple, and the capacitor C2 is the second barrel cap ( V2) For matching. (9 ', 9') is a filter of the second mixer 9, and (4 ') is a filter for providing the first mixer 4 signal to the second mixer 9.

본 발명은 우선 개략적으로 설명하면, 본 발명은 제2혼합기(9)에 주입되는 제2칼소오스(2nd Local Source)로서 VCXO 타입대신 PLL(서브 PLL(20))을 적용시킨 것으로, 이때 에코캔슬(Echo Cancel)용 서브 PLL(20)은 사용주파수 대역면에서 고려할때, 코스트면에서 메인 PLL(2) 구성에 필요한 소자들에 비해 비할수 없이 저렴하게 된다. 이는 서브 PLL(20)은 저주파대역이기 때문이다.The present invention is briefly described first, and the present invention applies a PLL (sub PLL 20) instead of a VCXO type as a second calsos (2nd Local Source) injected into the second mixer (9). In consideration of the frequency band used, the sub PLL 20 for (Echo Cancel) becomes inexpensive compared to the elements required for the main PLL 2 configuration in terms of cost. This is because the sub PLL 20 has a low frequency band.

따라서 각 루프정수(ωn, ξ, τT)등을 메인 PLL(2)과 동일하게 설정하고, 메인 PLL(2)과 2차 로칼용 서브 PLL(20)의 루프응답은 전대역에서 동일한 변조율은 기대할 수 있으며, 이것은 다시말하면 에코캔슬 효과를 대역의 특정부분이 아닌 전 사용대역으로 확장시킬 수 있음을 입증한다 하겠다. 또한 서브 PLL(20)을 사용하기에 체배기가 필요없고, 에코캔슬 효과가 전사용대역으로 확장되므로 전류소모와 타회로에 영향을 미치는 고조파(Harmonics)면에서 유리하고, 모든 모품이 표면실장화 할 수 있어 스페이스면에서 유리하다. 또한 서브 PLL(20)을 사용함으로 인하여 최소한 3개의 변성코일(IFT)이 필요없게 되어 조정포인트가 감소될 수 있고, 충분한 변조를 얻음과 동시에 주파수 안정도면에서 극히 뛰어난 특성을 기대할 수 있다.Therefore, each loop constant (ωn, ξ, τ T ), etc. is set to be the same as the main PLL (2), and the loop response of the main PLL (2) and the secondary local sub-PLL (20) is the same in all bands. In other words, this proves that the echo canceling effect can be extended to the full band rather than to a specific part of the band. In addition, a multiplier is not required to use the sub PLL 20, and the echo canceling effect is extended to the transfer band, which is advantageous in terms of harmonics that affect current consumption and other circuits, and all the parent products can be surface mounted. It is advantageous in terms of space. In addition, the use of the sub PLL 20 eliminates the need for at least three modified coils (IFTs), thereby reducing the adjustment point, and attaining sufficient modulation, and at the same time, extremely excellent frequency stability can be expected.

이는 VCXO에서 사용되던 크리스탈(X-tal)의 주파수 안정도가 ±50PPM정도이면 우수한 특성이라 할때, 여기서 4체배를 한다고 가정하면 주파수 안정도는 50×4=2000PPM이 되나, 본 발명에서는 ±2PPM이하의 온도보상발진기(TCXO)를 사용함으로써(메인 PLL(2)과 공용) 100배 이상의 향상된 효과를 얻는다.This is an excellent characteristic when the frequency stability of the crystal (X-tal) used in the VCXO is about 50 PPM. Here, assuming the multiplication, the frequency stability is 50 × 4 = 2000 PPM. However, in the present invention, the frequency stability is less than ± 2 PPM. By using the temperature compensating oscillator (TCXO) (shared with the main PLL 2), an effect of more than 100 times is obtained.

좀더 구체적으로 설명하면, 메인 PLL(2)과 전압제어발진기(1)에 의한 PLL작동은 종래와 동일하다. 대신 코일(1)과 콘덴서(Co)에 의한 발진회로(21)에 의해 발진된 주파수가 제2혼합기(9)에 제공됨과 아울러 콘덴서(C7)를 통해 서브 PLL(20)로 피드배되고, 서브 PLL(20)에 의한 피드백에러 신호는 저항(R1∼R4) 및 콘덴서(C3,C4)로 이루어진 3차 수동루프필터(LF)의 저항(R1)을 통해 제1배리캡(V1)에 주입되어 제1배리캡(V1)의 용량을 변화시키며, 결과적으로 발진회로(21)에 의한 발진주파수를 루프록(Loop Lock)한다.More specifically, the PLL operation by the main PLL 2 and the voltage controlled oscillator 1 is the same as in the prior art. Instead, the frequency oscillated by the oscillation circuit 21 by the coil 1 and the condenser Co is provided to the second mixer 9 and fed through the condenser C7 to the sub PLL 20. The feedback error signal by the PLL 20 is injected into the first barrel cap V1 through the resistor R1 of the third-pass passive loop filter LF including the resistors R1 to R4 and the capacitors C3 and C4. The capacitance of the first barrel cap V1 is changed, and as a result, the oscillation frequency by the oscillation circuit 21 is loop locked.

이때 온도보상발진기(TCXO : Temperature Compensated X-tal Oscillator)로부터의 기준신호(REF, Signal)와 위상비교를 위한 발진회로(21)의 출력신호는 콘덴서(C7)를 통해 서브 PLL(20)의 핀(fin) 단자에 주입된다. 이때 에코캔슬을 위하여 변조신호가 전압제어발진기(1)에 제공됨과 아울러 위상쉬프트 증폭기(10)에 의해 위상이 180도 쉬프트된 상태로 저항(R5)을 통해 제2배리캡(V2)에 인가되어 변조를 건다.At this time, the output signal of the oscillation circuit 21 for phase comparison with the reference signal (REF, Signal) from the temperature compensated oscillator (TCXO: TCXO) is connected to the pin of the sub PLL 20 through the capacitor C7. injected into the (fin) terminal. At this time, the modulation signal is provided to the voltage controlled oscillator 1 for echo cancellation and is applied to the second barrel cap V2 through the resistor R5 with the phase shifted by 180 degrees by the phase shift amplifier 10. Modulate

이 경우 변조특성(입력레벨, 주파수별)은 루프전달함수(B(S))에 전적으로 달여 있으며, 결국 루프필터의 특성이라 할 수 있다. 이때, 에코캔슬율(Rate)의 극대효과를 얻기 위한 에코캔슬 PLL의 바람직한 조건을 예시하면 다음과 같다.In this case, the modulation characteristics (input level, frequency) are entirely dependent on the loop transfer function B (S), which can be referred to as the characteristics of the loop filter. At this time, the preferred conditions of the echo cancellation PLL for obtaining the maximum effect of the echo cancellation rate (Rate) is as follows.

첫째로, 온도보상 발진기(TCXO)로 부터의 기준신호를 적절한 정수로 나눈값이 메인 PLL(2)의 채널스패이싱(Channel Spacing)의 fref±10%이내이어야 한다.First, the reference signal from the temperature compensation oscillator (TCXO) divided by the appropriate integer should be within fref ± 10% of the channel spacing of the main PLL (2).

둘째로, 상기 나눈값에 적절한 정수를 곱한값이 목표로하는 주파수의 ±2PPM이내가 바람직하다(±10PPM까지는 실용상 문제없으며, VCXO타입이 ±200PPM임을 감안할 때 ±2PPM인 본 발명은 주파수 안정도면에서 100배 정도 향상된다).Secondly, the value obtained by multiplying an appropriate integer by the divided value is preferably within ± 2PPM of the target frequency (no practical problem until ± 10PPM, and considering that the VCXO type is ± 200PPM, the present invention has a frequency stability diagram. 100 times better).

셋째로, 서브 PLL(20)의 핀(fin)으로 입력되는 발진주파수가 목적하는 주파수에 반응토록 함이 바람직하다.Third, it is preferable that the oscillation frequency input to the fin of the sub PLL 20 responds to the desired frequency.

이를 수식으로 나타내면,If this is expressed as a formula,

△fmain＞fTCXO/R＞0.9△fmain△ fmain> f TCXO / R> 0.9 △ fmain

(1+2×10-6)fosc＞fTCXO, N/R＞(1-2×10-6)fosc(1 + 2 × 10 -6 ) fosc> f TCXO , N / R> (1-2 × 10 -6 ) fosc

(여기서, N,R은 4이상의 정수, △fmain은 메인 PLL(2)의 채널스패이싱, fTCXO는 온도보상 발진기(TCXO)의 기준신호, fosc는 발진회로(21)에 의한 발진주파수이다).Where N and R are integers greater than or equal to 4, Δfmain is the channel spacing of the main PLL 2, f TCXO is the reference signal of the temperature compensation oscillator TCXO, and fosc is the oscillation frequency by the oscillator circuit 21. .

이상과 같이 본 발명은 루프정수가 동일하게 설정된 메인 PLL과 서브 PLL에 의하여 에코캔슬시키므로 전사용 대역(변조)에서 에코캔슬이 가능할 뿐만 아니라 고조파 성분 및 전류소모를 감소시킬 수 있고, 주파수 안정도면에서도 100배 정도의 향상을 이룰 수 있으며, 이동통신(Cellular System)의 단말기 구성일 경우 통화선로의 신뢰성이 향상(SAT의 S/N증가)될 뿐만 아니라 한 세트분의 전압제어 발진기 및 고품위 PLL IC비용이 절감된다.As described above, the present invention echo cancels by the main PLL and the sub PLL with the same loop constant, so that not only the echo cancellation is possible in the transfer band (modulation), but also the harmonic components and current consumption can be reduced, It can achieve about 100 times improvement, and in case of a mobile system (cell system), the reliability of the telephone line is not only improved (S / N increase of SAT) but also a set of voltage-controlled oscillator and high-quality PLL IC cost. This is reduced.

또한 에코캔슬을 위해 PLL방식을 사용하므로 기존에 비해 3개소 이상의 조정포인트가 감소되어 제조원가가 절감되고 생산성이 향상되며, 이에 따라 무조정이 가능하여 회로설계 및 테스트시간이 감축될 뿐만 아니라 외부삽입 및 조정부품이 필요없게 되어 표면실장화가 가능케 됨으로써 제품의 부피를 극소화시킬 수 있게 된다.In addition, the PLL method is used for eco-cancellation, which reduces three or more adjustment points compared to the existing ones, thereby reducing manufacturing costs and improving productivity. Accordingly, no adjustment is possible, which reduces circuit design and test time, as well as external insertion and Eliminating the need for adjustment components allows for surface mount, minimizing the volume of the product.

Claims (1)

무선기기의 1-PLL 에코캔슬 회로를 구성함에 있어서, 메인 PLL(2)과 동시에 기준신호를 온도보상 발진기(TCXO)로부터 제공받는 서브 PLL(20)과; 제2혼합기(9) 및 서브 PLL(20)에 발진주파수를 제공하도록 코일(L)과 콘덴서(Co)로 이루어진 발진회로(21)와; 발진회로(21)와 콘덴서(C1)를 통해 접속되며, 서브 PLL(20)의 위상 에러신호를 저항(R1∼R4) 및 콘덴서(C3,C4)로된 3차 수동루프필터(LF)를 통해 주입하여 발진주파수를 루프록(Loop Lock)시키는 제1배리캡(V1)과; 제1배리캡(V1)과 병렬로 접속되고, 변조신호를 받아 쉬프트되는 위상쉬프트 증폭기(10) 출력이 저항(R5)을 통해 에코캔슬용 변조를 거는 제2배리캡(V2)을 포함하여 구성됨을 특징으로 하는 무선기기의 에코캔슬 회로.In constructing a 1-PLL echo cancel circuit of a wireless device, a sub PLL (20) which receives a reference signal from a temperature compensation oscillator (TCXO) simultaneously with the main PLL (2); An oscillation circuit 21 composed of a coil L and a condenser Co so as to provide an oscillation frequency to the second mixer 9 and the sub PLL 20; The phase error signal of the sub PLL 20 is connected to the oscillation circuit 21 and the capacitor C1 through a third-order passive loop filter LF consisting of resistors R1 to R4 and capacitors C3 and C4. A first barrier cap V1 injected to loop the oscillation frequency; The output of the phase shift amplifier 10 connected in parallel with the first vari cap V1 and shifted in response to a modulated signal includes a second vari cap V2 for performing echo cancellation modulation through the resistor R5. Eco-cancel circuit of a wireless device characterized in that.
KR1019920004428A 1992-03-18 1992-03-18 Echo cancel circuit of radio frequency KR950001504B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108717840A (en) * 2016-04-25 2018-10-30 广东欧珀移动通信有限公司 A kind of adjusting method of display screen, regulating device and terminal and medium product

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108717840A (en) * 2016-04-25 2018-10-30 广东欧珀移动通信有限公司 A kind of adjusting method of display screen, regulating device and terminal and medium product
CN108717840B (en) * 2016-04-25 2019-09-27 Oppo广东移动通信有限公司 A kind of adjusting method of display screen, regulating device and terminal and medium product

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