TWI497924B - Signal transceiver capable of enhancing return loss under power-off state - Google Patents

可於電源關閉狀態下加強回波耗損之訊號收發器Signal transceiver that enhances echo loss when the power is off

本發明係指一種訊號收發器，尤指一種可於一電源關閉狀態下，有效加強回波耗損(return loss)的訊號收發器。The invention relates to a signal transceiver, in particular to a signal transceiver capable of effectively enhancing return loss of a power supply in a closed state.

同軸電纜乙太網路(Ethernet over Coax，EoC)係乙太網路訊號在同軸電纜上的一種傳輸技術，其目的在於利用現有有線電視的基礎設施連接網際網路或寬頻數據傳輸，兼容現有的有線電視(或衛星電視)廣播訊號，達成同時在同一條同軸電纜上傳輸數據訊號的目的。其中，多媒體同軸電纜聯盟(Multimedia over Coax Alliance，MoCA)制定的多媒體網路標準具無瑕疵(glitch-free)串流媒體所需的高速及高服務品質(QoS)功能等，透過現有同軸電纜，將訊號送至每一用戶端，用戶端只需一訊號收發器便可解調訊號以取得服務內容。Coaxial cable Ethernet over Coax (EoC) is a transmission technology of Ethernet signals on coaxial cable. Its purpose is to use the existing cable TV infrastructure to connect to the Internet or broadband data transmission, compatible with existing ones. Cable television (or satellite TV) broadcast signals to achieve the purpose of transmitting data signals on the same coaxial cable at the same time. Among them, the multimedia network standard developed by the Multimedia over Coax Alliance (MoCA) has the high-speed and high quality of service (QoS) functions required for glitch-free streaming media, through existing coaxial cables. The signal is sent to each client, and the client only needs a signal transceiver to demodulate the signal to obtain the service content.

請參考第1圖，第1圖為習知一訊號收發器10之示意圖。訊號收發器10包含有一連接器100、一帶通濾波器(band-pass filter，BPF)102及一前端模組104。通常，訊號收發器10以機上盒(set-top box，STB)產品實現。連接器100連接一同軸電纜，用來接收透過同軸電纜傳輸的訊號，包含有符合多媒體同軸電纜聯盟的訊號(以下稱MoCA訊號)。帶通濾波器(band-pass filter，BPF)102用來過濾訊號，以濾出一頻帶範圍內的訊號。舉例來說，美國衛星電視服務供應商DIRECTVTM提供之MoCA訊號的頻帶範圍介於475MHz至625MHz之間。若只需保留此MoCA訊號，則帶通濾波器102的濾波頻帶範圍應設定為475MHz至625MHz。前端模組104用以將 通過帶通濾波器102的訊號解調。一般而言，前端模組104包含有傳輸接收器、功率放大器及衰減器等電路，且前端模組104通常被整合於一積體電路(integrated circuit，IC)內。Please refer to FIG. 1 , which is a schematic diagram of a conventional signal transceiver 10 . The signal transceiver 10 includes a connector 100, a band-pass filter (BPF) 102 and a front end module 104. Typically, the signal transceiver 10 is implemented in a set-top box (STB) product. The connector 100 is connected to a coaxial cable for receiving signals transmitted through the coaxial cable, and includes a signal conforming to the Multimedia Coaxial Cable Alliance (hereinafter referred to as a MoCA signal). A band-pass filter (BPF) 102 is used to filter the signals to filter out signals in a range of frequencies. For example, the MoCA signal provided by US satellite TV service provider DIRECTVTM ranges from 475MHz to 625MHz. If it is only necessary to retain this MoCA signal, the filter band range of the band pass filter 102 should be set to 475 MHz to 625 MHz. The front end module 104 is used to The signal is demodulated by the band pass filter 102. Generally, the front end module 104 includes circuits such as a transmission receiver, a power amplifier, and an attenuator, and the front end module 104 is generally integrated into an integrated circuit (IC).

請參考第2A圖與第2B圖，第2A圖與第2B圖分別為訊號收發器10在電源開啟狀態下與在電源關閉狀態下，且在475MHz~625MHz的頻帶內，接上連接器100之一同軸電纜(圖示未繪出)與連接器100之間的回波耗損之示意圖。比較第2A圖與第2B圖可知，在475MHz~625MHz的頻帶內，訊號收發器10於電源關閉狀態下的最小回波耗損接近7.6dB，小於訊號收發器10於電源開啟狀態下的最小回波耗損(接近11dB)大約3.4dB。由上述可知，若訊號收發器10操作於電源關閉狀態下，確實會導致系統效能變差。Please refer to FIG. 2A and FIG. 2B. FIG. 2A and FIG. 2B respectively show the signal transceiver 10 in the power-on state and in the power-off state, and in the frequency band of 475 MHz to 625 MHz, the connector 100 is connected. Schematic diagram of echo loss between a coaxial cable (not shown) and connector 100. Comparing FIG. 2A and FIG. 2B, the minimum echo loss of the signal transceiver 10 in the power-off state is close to 7.6 dB in the frequency band of 475 MHz to 625 MHz, which is smaller than the minimum echo of the signal transceiver 10 in the power-on state. The loss (near 11dB) is about 3.4dB. It can be seen from the above that if the signal transceiver 10 is operated in the power-off state, the system performance will be deteriorated.

因此，本發明的主要目的即在於提供一種訊號收發器，其可於電源開啟及關閉的狀態下，皆維持良好的回波耗損。Accordingly, it is a primary object of the present invention to provide a signal transceiver that maintains good echo loss in both the power on and off states.

本發明揭露一種可於一電源關閉狀態下加強回波耗損之訊號收發器，包含有一連接器，用來接收一訊號；一帶通濾波器，耦接於該連接器，用來過濾該訊號；一前端模組，用來解調該訊號；以及一阻抗轉換電路，耦接於該帶通濾波器及該前端模組之間，用來轉換該訊號收發器之一輸入阻抗值，其包含有一輸入端，耦接於該帶通濾波器，用來接收該訊號；一輸出端，耦接於該前端模組，用來輸出該訊號至該前端模組；一阻抗轉換單元；以及一第一電源輸入電路，其一端耦接於該阻抗轉換單元，用來提供一電源；其中，該阻抗轉換單元耦接於該第一電源輸入電路與該輸入端之間，用來轉換該訊號收發器之該輸入阻抗值。The present invention discloses a signal transceiver capable of enhancing echo loss in a power-off state, comprising a connector for receiving a signal, and a band pass filter coupled to the connector for filtering the signal; a front end module for demodulating the signal; and an impedance conversion circuit coupled between the band pass filter and the front end module for converting an input impedance value of the signal transceiver, comprising an input The end is coupled to the band pass filter for receiving the signal; an output end coupled to the front end module for outputting the signal to the front end module; an impedance conversion unit; and a first power supply An input circuit, one end of which is coupled to the impedance conversion unit for providing a power source; wherein the impedance conversion unit is coupled between the first power input circuit and the input terminal for converting the signal transceiver Enter the impedance value.

10、30‧‧‧訊號收發器10, 30‧‧‧ Signal Transceiver

100、300‧‧‧連接器100, 300‧‧‧ connectors

102、302‧‧‧帶通濾波器102, 302‧‧‧ bandpass filter

304‧‧‧阻抗轉換電路304‧‧‧ impedance conversion circuit

104、306‧‧‧前端模組104, 306‧‧‧ front-end module

400‧‧‧輸入端400‧‧‧ input

402‧‧‧輸出端402‧‧‧output

404、406‧‧‧電源輸入電路404, 406‧‧‧ power input circuit

408‧‧‧阻抗轉換單元408‧‧‧impedance conversion unit

410‧‧‧偏壓電路410‧‧‧Bias circuit

412‧‧‧電源供應端412‧‧‧Power supply

Vcc‧‧‧輸入電壓Vcc‧‧‧ input voltage

R1、R2、R3、R4‧‧‧電阻R1, R2, R3, R4‧‧‧ resistance

N1、N2‧‧‧節點N1, N2‧‧‧ nodes

T1‧‧‧傳輸線T1‧‧‧ transmission line

D1、D2‧‧‧開關D1, D2‧‧‧ switch

P1、P2‧‧‧箭號P1, P2‧‧‧ arrows

第1圖為習知一訊號收發器之示意圖。Figure 1 is a schematic diagram of a conventional signal transceiver.

第2A圖為第1圖之訊號收發器於電源開啟狀態下，且在一特定頻帶內，接上連接器之一同軸電纜與連接器之間的回波耗損之示意圖。Fig. 2A is a schematic diagram showing the echo loss between the coaxial cable and the connector of the connector in the power-on state of the signal transceiver of Fig. 1 in a specific frequency band.

第2B圖為第1圖之訊號收發器於電源關閉狀態下，且在一特定頻帶內，接上連接器之一同軸電纜與連接器之間的回波耗損之示意圖。FIG. 2B is a schematic diagram of the echo loss between the coaxial cable and the connector of the connector of the first embodiment in the power-off state of the signal transceiver of FIG. 1 .

第3圖為本發明實施例一訊號收發器之示意圖。FIG. 3 is a schematic diagram of a signal transceiver according to an embodiment of the present invention.

第4A圖為第3圖之阻抗轉換電路之示意圖。Fig. 4A is a schematic diagram of the impedance conversion circuit of Fig. 3.

第4B圖為第3圖之訊號收發器於電源開啟狀態下，電流方向之示意圖。Figure 4B is a schematic diagram of the current direction of the signal transceiver of Figure 3 in the power-on state.

第4C圖為第3圖之訊號收發器於電源關閉狀態下，電流方向之示意圖。Figure 4C is a schematic diagram of the current direction of the signal transceiver of Figure 3 in a power-off state.

第5A圖為第3圖之訊號收發器於電源開啟狀態下，且在一特定頻帶內，帶通濾波器與前端模組之間的回波耗損之示意圖。Fig. 5A is a schematic diagram showing the echo loss between the band pass filter and the front end module in the power-on state of the signal transceiver of Fig. 3 in a specific frequency band.

第5B圖為第3圖之訊號收發器於電源關閉狀態下，且在一特定頻帶內，帶通濾波器與前端模組之間的回波耗損之示意圖。FIG. 5B is a schematic diagram of the echo loss between the band pass filter and the front end module in the signal off state of the signal transceiver of FIG. 3 in a specific frequency band.

第6A圖為第3圖之訊號收發器於電源開啟狀態下，且在一特定頻帶內，訊號收發器的回波耗損之示意圖。Fig. 6A is a schematic diagram showing the echo loss of the signal transceiver in the signal-on state of the signal transceiver of Fig. 3 in a specific frequency band.

第6B圖為第3圖之訊號收發器於電源關閉狀態下，且在一特定頻帶內，訊號收發器的回波耗損之示意圖。Fig. 6B is a schematic diagram showing the echo loss of the signal transceiver in the signal off state of the signal transceiver of Fig. 3 in a specific frequency band.

請參考第3圖，第3圖為本發明實施例一訊號收發器30之示意圖。訊號收發器30包含有一連接器300、一帶通濾波器302、一阻抗轉換電路304及一前端模組306。連接器300、帶通濾波器302、前端模組306分別與習知訊號收發器10之連接器100、帶通濾波器102、前端模組104相同，在此不贅述。阻抗轉換電路304耦接於帶通濾波器302與前端模組306之間，用來轉換訊號收發器30之一輸入阻抗值。Please refer to FIG. 3, which is a schematic diagram of a signal transceiver 30 according to an embodiment of the present invention. The signal transceiver 30 includes a connector 300, a band pass filter 302, an impedance conversion circuit 304, and a front end module 306. The connector 300, the band pass filter 302, and the front end module 306 are the same as the connector 100, the band pass filter 102, and the front end module 104 of the conventional signal transceiver 10, and are not described herein. The impedance conversion circuit 304 is coupled between the band pass filter 302 and the front end module 306 for converting an input impedance value of the signal transceiver 30.

關於阻抗轉換電路304的實施方式，請參考第4A圖。阻抗轉換電路304包含有一輸入端400、一輸出端402、電源輸入電路404、406、一阻抗轉換單元408、一偏壓電路410及一開關D1。輸入端400耦接於帶通濾 波器302，用來接收通過帶通濾波器302的訊號。輸出端402耦接於前端模組306，用來將通過帶通濾波器302的訊號輸出至前端模組306。電源輸入電路404、406用來提供輸入電壓Vcc。電源輸入電路404、406分別包含有電阻R1、R2。電阻R1耦接於一電源供應端412與阻抗轉換單元408之間，而電阻R2耦接於電源供應端412與輸入端400之間，電阻R1、R2皆用來接收輸入電壓Vcc。阻抗轉換單元408包含有一傳輸線T1及一電阻R3。傳輸線T1之一端耦接於電源輸入電路404，其等效長度大致上等於所收發之訊號的四分之一波長，可於訊號收發器30之一操作頻段下轉換輸入阻抗值。傳輸線T1之另一端耦接於電阻R3，電阻R3之一端耦接於輸入端400。偏壓電路410耦接於輸入端400與輸出端402之間，用來轉換訊號之電壓值。偏壓電路410包含有一電阻R4及開關D2。上述開關D1、D2較佳地可使用二極體來實現，而電阻R3的電阻值可根據連接至連接器300之一元件決定，例如可以是一同軸電纜之特徵阻抗值(即75Ohm)。For an embodiment of the impedance conversion circuit 304, please refer to FIG. 4A. The impedance conversion circuit 304 includes an input terminal 400, an output terminal 402, power supply input circuits 404, 406, an impedance conversion unit 408, a bias circuit 410, and a switch D1. The input terminal 400 is coupled to the band pass filter The waver 302 is configured to receive a signal that passes through the bandpass filter 302. The output end 402 is coupled to the front end module 306 for outputting the signal passing through the band pass filter 302 to the front end module 306. Power input circuits 404, 406 are used to provide an input voltage Vcc. The power input circuits 404, 406 respectively include resistors R1, R2. The resistor R1 is coupled between the power supply terminal 412 and the impedance conversion unit 408, and the resistor R2 is coupled between the power supply terminal 412 and the input terminal 400. The resistors R1 and R2 are used to receive the input voltage Vcc. The impedance conversion unit 408 includes a transmission line T1 and a resistor R3. One end of the transmission line T1 is coupled to the power input circuit 404, and its equivalent length is substantially equal to a quarter wavelength of the transmitted and received signal, and the input impedance value can be converted in an operating frequency band of the signal transceiver 30. The other end of the transmission line T1 is coupled to the resistor R3, and one end of the resistor R3 is coupled to the input terminal 400. The bias circuit 410 is coupled between the input terminal 400 and the output terminal 402 for converting the voltage value of the signal. The bias circuit 410 includes a resistor R4 and a switch D2. The above switches D1, D2 can preferably be implemented using a diode, and the resistance value of the resistor R3 can be determined according to one of the components connected to the connector 300, for example, a characteristic impedance value of a coaxial cable (i.e., 75 Ohm).

第4B圖及第4C圖分別說明訊號收發器30之一電源開啟及關閉狀態時，阻抗轉換電路304的電流方向。如第4B圖所示，於電源開啟狀態下，開關D1、D2均為導通狀態；此時，節點N1相當於短路(short circuit)，為低阻抗，再經過四分之一波長的傳輸線T1轉換阻抗之後，節點N2相當於開路(open circuit)，為高阻抗，因此射頻訊號流經開關D2(流向如箭號P1所示)，而傳遞至前端模組306。接著，如第4C圖所示，當訊號收發器30的電源關閉時，開關D1、D2均為不導通狀態；節點N1相當於開路，為高阻抗，再經過四分之一波長的傳輸線T1轉換阻抗之後，節點N2相當於短路，為低阻抗，因此射頻訊號流經電阻R3及傳輸線T1(流向如箭號P2所示)，不傳送至前端模組306。換言之，當訊號收發器30的電源關閉時，於輸入端400所看到的輸入阻抗值即大致等於電阻R3之值，因此可達到阻抗匹配的效果，進而改善於電源關閉狀態下的回波耗損。4B and 4C illustrate the current direction of the impedance conversion circuit 304 when the power of the signal transceiver 30 is turned on and off, respectively. As shown in FIG. 4B, in the power-on state, the switches D1 and D2 are all in a conducting state; at this time, the node N1 is equivalent to a short circuit, which is a low impedance, and then is converted by a quarter-wavelength transmission line T1. After the impedance, the node N2 is equivalent to an open circuit and is high impedance. Therefore, the RF signal flows through the switch D2 (flow direction is indicated by an arrow P1) and is transmitted to the front end module 306. Then, as shown in FIG. 4C, when the power of the signal transceiver 30 is turned off, the switches D1 and D2 are in a non-conducting state; the node N1 is equivalent to an open circuit, is high impedance, and is converted by a quarter-wavelength transmission line T1. After the impedance, the node N2 is equivalent to a short circuit and is low impedance. Therefore, the RF signal flows through the resistor R3 and the transmission line T1 (flow direction is indicated by an arrow P2) and is not transmitted to the front end module 306. In other words, when the power of the signal transceiver 30 is turned off, the input impedance value seen at the input terminal 400 is substantially equal to the value of the resistor R3, so that the impedance matching effect can be achieved, thereby improving the echo loss in the power-off state. .

請參考第5A圖與第5B圖，第5A圖與第5B圖分別為訊號收發 器30操作於電源開啟狀態與電源關閉狀態時，帶通濾波器302與前端模組306之間的回波耗損之示意圖。比較第5A圖與第5B圖可知，在475MHz~625MHz的頻帶內，於電源開啟狀態下訊號收發器30之輸入端400的最小回波耗損約為20dB，而於電源關閉狀態下訊號收發器30之輸入端400的回波耗損可達12dB以上。由上述可知，訊號收發器30操作於電源關閉狀態下，帶通濾波器302與前端模組306之間的回波耗損相較於習知技術可被有效提升。Please refer to the 5A and 5B diagrams. The 5A and 5B diagrams are for signal transmission and reception. Schematic diagram of the echo loss between the bandpass filter 302 and the front end module 306 when the device 30 is operating in the power on state and the power off state. Comparing FIGS. 5A and 5B, it can be seen that in the frequency band of 475 MHz to 625 MHz, the minimum echo loss of the input terminal 400 of the signal transceiver 30 is about 20 dB in the power-on state, and the signal transceiver 30 is in the power-off state. The return loss of the input terminal 400 can be more than 12 dB. As can be seen from the above, when the signal transceiver 30 is operated in the power-off state, the echo loss between the band pass filter 302 and the front end module 306 can be effectively improved compared to the prior art.

請參考第6A圖與第6B圖，第6A圖與第6B圖分別為訊號收發器30操作於電源開啟狀態與電源關閉狀態時，阻抗轉換電路304之輸入端400接上連接器300之一同軸電纜(圖示未繪出)後，訊號收發器30的回波耗損之示意圖。比較第6A圖與第6B圖可知，在475MHz~625MHz的頻帶內，訊號收發器30於電源開啟狀態下的最小回波耗損約為11dB，而訊號收發器30於電源關閉狀態下的最小回波耗損接近11.5dB。由上述可知，訊號收發器30不論是操作於電源開啟或關閉狀態下，皆能維持良好的回波耗損。Please refer to FIG. 6A and FIG. 6B. FIG. 6A and FIG. 6B respectively show the input terminal 400 of the impedance conversion circuit 304 connected to the coaxial connector 300 when the signal transceiver 30 is operated in the power-on state and the power-off state. Schematic diagram of the echo loss of the signal transceiver 30 after the cable (not shown). Comparing FIGS. 6A and 6B, it can be seen that in the frequency band of 475 MHz to 625 MHz, the minimum echo loss of the signal transceiver 30 in the power-on state is about 11 dB, and the minimum echo of the signal transceiver 30 in the power-off state. The loss is close to 11.5dB. As can be seen from the above, the signal transceiver 30 can maintain good echo loss regardless of whether the power is turned on or off.

應注意的是，本發明將包含傳輸線之阻抗轉換電路耦接於帶通濾波器與前端模組之間，以改善電源關閉狀態下的回波耗損，並有效降低生產成本。本領域具通常知識者當可據以做不同之修飾，而不限於此。舉例來說，傳輸線T1之特徵阻抗可根據連接於連接器300之一元件(如同軸電纜等)決定，亦可適應性地調整為其他數值，只要輸入阻抗值經過傳輸線T1可由低阻抗(如短路)轉換為高阻抗(如開路)，或由高阻抗(如開路)轉換為低阻抗(如短路)即可。此外，傳輸線T1可為直線、蜿蜒線等，而其線段間距亦可適應性的調整，只要傳輸線T1可等效為四分之一波長的傳輸線即可。It should be noted that the present invention couples the impedance conversion circuit including the transmission line between the band pass filter and the front end module to improve the echo loss in the power off state and effectively reduce the production cost. Those skilled in the art will be able to make various modifications, and are not limited thereto. For example, the characteristic impedance of the transmission line T1 can be determined according to a component connected to the connector 300 (such as a coaxial cable, etc.), or can be adaptively adjusted to other values, as long as the input impedance value passes through the transmission line T1 can be low impedance (such as a short circuit). ) Convert to high impedance (such as an open circuit), or convert from a high impedance (such as an open circuit) to a low impedance (such as a short circuit). In addition, the transmission line T1 can be a straight line, a squall line, etc., and the line segment spacing can also be adaptively adjusted, as long as the transmission line T1 can be equivalent to a quarter-wavelength transmission line.

再者，上述第5B圖及第6B圖僅繪示在475MHz~625MHz的頻帶內，訊號收發器30於電源關閉狀態下的最小回波耗損可有效增加。在本領域中具通常知識者當可根據不同頻帶調整各元件的特性，使在不同頻帶範圍內的最小回波耗損可有效增加。Furthermore, the above FIG. 5B and FIG. 6B only show that the minimum echo loss of the signal transceiver 30 in the power-off state can be effectively increased in the frequency band of 475 MHz to 625 MHz. Those of ordinary skill in the art can adjust the characteristics of the various components according to different frequency bands so that the minimum echo loss in different frequency bands can be effectively increased.

本發明實施例之阻抗轉換電路304可為一獨立電路，耦接於帶通濾波器302與前端模組306之間。然而，應注意的是，阻抗轉換電路304另可與前端模組306整合為一積體電路。The impedance conversion circuit 304 of the embodiment of the present invention can be an independent circuit coupled between the band pass filter 302 and the front end module 306. However, it should be noted that the impedance conversion circuit 304 can be integrated with the front end module 306 as an integrated circuit.

習知訊號收發器於電源關閉狀態下，回波耗損會明顯降低，導致系統效能變差。相較之下，本發明之訊號收發器透過阻抗轉換電路，轉換帶通濾波器與前端模組之間的阻抗，使訊號收發器可於電源關閉狀態下，有效改善回波耗損，以提昇系統效能。此外，本發明可使用簡單電路元件實現阻抗轉換電路，因而可進一步降低訊號收發器的生產成本。When the conventional signal transceiver is turned off, the echo loss will be significantly reduced, resulting in poor system performance. In contrast, the signal transceiver of the present invention converts the impedance between the band pass filter and the front end module through the impedance conversion circuit, so that the signal transceiver can effectively improve the echo loss in the power off state, thereby improving the system. efficacy. In addition, the present invention can implement an impedance conversion circuit using a simple circuit component, thereby further reducing the production cost of the signal transceiver.

以上所述僅為本發明之較佳實施例，凡依本發明申請專利範圍所做之均等變化與修飾，皆應屬本發明之涵蓋範圍。The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

30‧‧‧訊號收發器30‧‧‧Signal Transceiver

300‧‧‧連接器300‧‧‧Connector

302‧‧‧帶通濾波器302‧‧‧Bandpass filter

304‧‧‧阻抗轉換電路304‧‧‧ impedance conversion circuit

306‧‧‧前端模組306‧‧‧ Front End Module