Continuous time lenear equallizer

Abstract

The present invention discloses a continuous-time linear equalizer circuit that can have a higher bandwidth by means of a plurality of filters connected to different signal paths separated in a T-coil circuit.

Description

Technology Field

[0001] The present invention relates to a technology using a continuous-time linear equalizer circuit utilizing a T-coil in a receiving end used for data transmission, and to a circuit structure that enables a higher bandwidth by utilizing two filters. Background Technology

[0002] Data transmission is one of the important functions of integrated circuit devices. With the development of integrated circuit technology, data transmission speeds have also gradually increased. In particular, as wired and wireless data transmission technologies reached the gigahertz (GHz) range, integrated circuits transmitting or receiving wireless data also needed to be capable of processing data with frequency bands in the gigahertz range. When a signal with a high frequency band is input to the receiver of an integrated circuit, mutual matching is required between the input signal and the impedance of the input node; this necessity increases as the frequency rises. If impedance matching is not properly performed at the receiver, the bandwidth of the signal input to the receiver will eventually be reduced due to signal reflection at the terminal. In the receiver of an integrated circuit, a T-coil circuit is sometimes used as one of the circuits for impedance matching.

[0003] The input nodes of an integrated circuit also require an electrostatic discharge (ESD) protection circuit to prevent internal components from being destroyed by static electricity. This is because the pins through which signals are transmitted are exposed to the outside, making them highly susceptible to static electricity. If internal components are destroyed by static electricity, they suffer irreversible damage. Most ESD protection circuits consist of a proper combination of reverse-connected diodes, resistors, and capacitors. Meanwhile, the impedance component of the ESD protection circuit can also sometimes affect impedance matching.

[0004] A continuous signal linear equalizer circuit that tracks the input signal well is sometimes used at the receiving end of an integrated circuit that receives a signal input at high speed. As mentioned above, the bandwidth of the continuous signal linear equalizer circuit is reduced by electrostatic discharge protection circuits, T-coil circuits, etc., and as the signal is received at high speed, this becomes an increasingly significant problem, so a circuit with a higher bandwidth is needed. The problem to be solved

[0005] The technical problem that the present invention aims to solve is to increase the bandwidth of a continuous signal linear equalizer circuit using a T-coil.

[0006] The technical problem to be solved by the present invention is to provide a receiving circuit capable of receiving a signal input at increasingly high speeds without attenuation of magnitude or bandwidth.

[0007] Another technical problem that the present invention aims to solve is to enable a semiconductor chip or an electronic circuit system using the present invention to be advantageous for higher-speed signal processing. means of solving the problem

[0008] To solve the above problem, a continuous signal linear equalizer using a T-coil according to one embodiment of the present invention is characterized by comprising: a T-coil circuit in which a capacitive load is connected to one of the parallel-connected paths and at least two inductive loads are connected to another path; a first filter coupled to the one path; a second filter coupled to the other path; and a coupling part in which the output of the first filter and the output of the second filter are coupled to each other.

[0009] To solve the above problem, a continuous signal linear equalizer using a T-coil according to another embodiment of the present invention includes at least two T-coil circuits, in which a capacitive load is connected to one path among the parallel-connected paths and at least two inductive loads are connected to another path; and a coupling part in which one of the inputs of a first filter is connected to the output coupled to the one path of a first T-coil circuit among the T-coil circuits, another of the inputs of the first filter is connected to the output coupled to the other path of a second T-coil circuit among the other T-coil circuits, one of the inputs of a second filter is connected between the two inductive loads of the first T-coil circuit, another of the inputs of the second filter is connected between the two inductive loads of the second T-coil circuit, and the output of the first filter and the output of the second filter are coupled to each other. Effects of the invention

[0010] The bandwidth of the receiving circuit receiving a high-speed serial input signal is increased by the present invention.

[0011] In addition, a semiconductor chip adopting the receiving circuit of the present invention can also provide faster signal processing.

[0012] In addition, the electronic circuit or system incorporating the present invention has the effect of minimizing signal attenuation and increasing bandwidth even when processing higher-speed signals. Brief explanation of the drawing

[0013] FIG. 1 illustrates an embodiment of the present invention. FIG. 2 illustrates an embodiment of the T-coil circuit of the present invention. Figure 3 schematically illustrates the bandwidth increase effect according to the present invention. FIG. 4 illustrates another embodiment of the present invention. Specific details for implementing the invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. Among the reference numerals presented in each drawing, identical reference numerals indicate identical components.

[0015] In describing the present invention, if it is determined that a detailed description of related known technology may obscure the essence of the present invention, such detailed description is omitted.

[0016] Terms such as first, second, etc., may be used to describe various components, but said components are not limited by said terms, and said terms are used only for the purpose of distinguishing one component from another.

[0017] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and FIGS. 2. A continuous-time linear equalizer (100) is one of the circuits that receives a signal propagating at high speed, and is abbreviated as CTLE ( C Ontinuous T ime L inear E It is called a qualizer. The continuous-time linear equalizer (100) of the present invention includes a T-coil circuit (110), a first filter (130), a second filter (150), and a coupling part (170). If necessary, an anti-static element (160) for preventing static electricity and an element (140) for impedance matching may also be included.

[0018] In particular, input pins, which are pathways for input from the outside into the integrated circuit, are exposed to external static electricity, so there is a possibility that the gate oxide film of the transistor may be destroyed. To prevent this, an electrostatic discharge prevention device (160) is used, and components such as resistors, capacitors, and diodes are used in appropriate combination or individually. In particular, due to the capacitive load of the electrostatic discharge prevention device (160), the signal is delayed, which is disadvantageous for high-speed operation. Capacitive load refers to parasitic capacitance inside the electrostatic discharge prevention device (160) or capacitors placed as passive components.

[0019] The voltage at the input node of the continuous-time linear equalizer (100) is indicated as Vin, and the voltage at the output node is indicated as Vout. The component (120) connected to the input node is intended to represent the equivalent impedance of the input terminal and is commonplace to those who understand microwaves, and may not refer to a specific active or passive component. This is because as the frequency of the signal increases, the so-called transmission line effect appears in the input channel through which the signal is transmitted, so this is indicated as the characteristic impedance of the channel (Zin, reference numeral 120).

[0020] The specific indication of the channel's characteristic impedance is intended to show that characteristic impedance can be represented as a combination of resistance and capacitance, and that this characteristic results in the channel exhibiting low-pass filter properties, thereby attenuating high-frequency components of the signal. This is a well-known fact among engineers dealing with high-frequency signals.

[0021] The first filter (130) and the second filter (150) have different bandwidths (BW, B and W It may have idth), and the coupling part (170) has the function of adding or subtracting the output signals of the first filter (130) and the second filter (150).

[0022] The T-coil circuit (110) is located at the front end of the continuous-time linear equalizer (100) to receive an input voltage (Vin). The received input voltage may be a continuous signal of serial data operating at high speed. The received signal is divided into two or more paths within the T-coil circuit (110) and transmitted to the outputs (Vt1, Vt2) of the T-coil circuit (110) through each different path. The elements (111, 113, 115) forming the T-coil circuit (110) are composed of passive and active elements as needed, and include coils. An example of the elements inside the T-coil circuit (110) can be represented as a capacitive load (111) and an inductive load (113, 115), as shown in FIG. 2. The capacitive load (111) and the inductive load (113, 115) are connected in parallel with each other. Two inductive loads (113, 115) are connected in series, and the signal transmission path between them is divided.

[0023] FIG. 2 shows a representative embodiment of a T-coil circuit (110) that can be configured, in which two or more signal paths are formed by configuring capacitive loads and inductive loads in various combinations. Naturally, various embodiments can be configured by combining capacitive loads and inductive loads in various ways.

[0024] The first filter (130) and the second filter (150), which exist in different signal paths, have different bandwidths, and these can be changed to a desired bandwidth by the function of the coupling part (170). This feature of the present invention occurs as the total capacitance on the input side is divided into different paths by each filter, and more specifically, because the capacitance on the input side acting as a pole of the transfer function is effectively halved. FIG. 3 shows the frequency characteristics of the first filter (130) and the second filter (150), where the vertical axis represents the signal magnitude and the horizontal axis represents the frequency. The bandwidth of the first filter (130) is indicated as f1, and the bandwidth of the second filter (150) is indicated as f2, in the case where f1 > f2. In the graph of FIG. 3, the vertical axis can be displayed in decibels (dB), and the horizontal axis can be displayed in a logarithmic scale. Due to the addition or subtraction function of the coupling part (170), the output signal Vout of the continuous-time linear equalizer (100) has an increased bandwidth. Bandwidth (BW, B and W Although there may be some differences depending on the definition of idth, it is generally based on a value where the signal magnitude decreases by about 3dB from the midband, and the same applies to the present invention.

[0025] In FIG. 1, which illustrates an embodiment of the present invention, a filter (130) having a higher cutoff frequency among two filters is connected to a node of a path connected from one output node (Vt1) of a T-coil circuit (110) or one terminal of a capacitive load (111), and a filter (150) having a lower cutoff frequency is connected to a node of a path formed between another output node (Vt2) of a T-coil circuit (110) or an inductive load (113, 115) connected in series. Alternatively, this connection configuration of FIG. 1 is expressed such that the filter (130) having a higher cutoff frequency among two filters is connected to a node such as an impedance matching element (140), and the filter (150) having a lower cutoff frequency is connected to a node such as an electrostatic discharge protection element (160). With this embodiment, the gain attenuation phenomenon, which becomes more severe at higher frequencies due to the pole effect in the frequency characteristics of the T-coil circuit (110) or two filters, can be further reduced.

[0026] Another embodiment of the present invention is a continuous-time linear equalizer (300) that processes differential signals (Vin1, Vin2) when they are input, as shown in FIG. 4. In this case, the configuration of filters (330, 530) can be configured to have differential inputs and differential outputs, and includes two T-coil circuits (310, 510). As in the previous embodiment, the element (320, 520) connected to the differential input (Vin1, Vin2) represents the equivalent impedance of the receiving channel at the input terminal. Likewise, an impedance matching element (340, 540) is also connected to each T-coil circuit. Likewise, an electrostatic discharge protection element (360, 560) is also connected to each T-coil circuit.

[0027] Similar to the preceding embodiment, each of the two T-coil circuits (310, 510) has an output signal of a different path. The output nodes (Vt11, Vt12) of the first T-coil circuit (310) are each connected to one of the differential input terminals of the filters (330, 530). The output nodes (Vt21, Vt22) of the second T-coil circuit (510) are each connected to the other of the differential input terminals of the filters (330, 530).

[0028] One of the differential outputs of the filters (330, 530) is input to the first coupling part (370) among the coupling parts (370, 570), thereby performing an addition or subtraction operation, and the result is transmitted to the output (Vout1). The remaining one of the differential outputs of the filters (330, 530) is input to the second coupling part (570), thereby performing an addition or subtraction operation, and the result is transmitted to the output (Vout2). Thus, the original circuit operation of the continuous-time linear equalizer (300) of the present invention for differential input is completed.

[0029] In the operation of the continuous-time linear equalizer (300) for differential input, a bandwidth increase phenomenon occurs due to an operating principle similar to that of the embodiment of the present invention described above. It is easy to see that when the transfer function is calculated for the circuit of the present invention including the channel, an effect similar to that shown in FIG. 3 appears, and this can be intuitively understood by circuit designers. Furthermore, this applies equally to all embodiments of the present invention. For example, if the transfer function of the channel is H1(s) and the transfer function of the T-coil and filters is H2(s), the total transfer function in the frequency domain is expressed as a product, so it becomes H1(s)*H2(s). At this time, in the present invention, the bandwidth improvement effect of H2(s) ultimately results in an overall bandwidth improvement effect including the channel.

[0030] The present invention enables the implementation of a continuous-time linear equalizer having a higher bandwidth. In particular, the application of the present invention is desirable as the reception of higher speed signals is required in integrated circuits, electronic circuit systems, etc., having a serial interface.

[0031] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto and can be implemented in various other embodiments based on the basic concept of the present invention as defined in the following claims, and such embodiments are also included within the scope of the present invention.

Claims

Claim 1 A continuous-time linear equalizer characterized by comprising: a T-coil circuit in which a capacitive load is connected to one of the parallel-connected paths and at least two inductive loads connected in series are connected to another path; an input of a first filter coupled to the one path; an input of a second filter coupled between the two inductive loads; and a coupling portion in which the output of the first filter and the output of the second filter are coupled to each other. Claim 2 delete Claim 3 A continuous-time linear equalizer according to claim 1, characterized in that an anti-static element is connected between the two inductive loads. Claim 4 A continuous-time linear equalizer according to claim 1, characterized in that the first filter and the second filter are low-pass filters. Claim 5 A continuous-time linear equalizer according to claim 1, characterized in that the first filter and the second filter have different bandwidths. Claim 6 A continuous-time linear equalizer according to claim 1, characterized in that a load for impedance matching is connected to the T-coil. Claim 7 A continuous-time linear equalizer according to claim 1, characterized in that the coupling part has the function of adding or subtracting the output of the first filter and the output of the second filter. Claim 8 delete Claim 9 A continuous-time linear equalizer characterized by comprising: at least two T-coil circuits, wherein one path among the parallel-connected paths has a capacitive load connected thereto and at least two inductive loads connected to the other path; and a coupling portion wherein one of the inputs of a first filter is connected to the output coupled to the one path of a first T-coil circuit among the T-coil circuits, another of the inputs of the first filter is connected to the output coupled to the other path of a second T-coil circuit among the other T-coil circuits, one of the inputs of a second filter is connected between the two inductive loads of the first T-coil circuit, another of the inputs of the second filter is connected between the two inductive loads of the second T-coil circuit, and the output of the first filter and the output of the second filter are coupled to each other. Claim 10 A continuous-time linear equalizer according to claim 9, characterized in that an anti-static element is connected between the two inductive loads. Claim 11 A continuous-time linear equalizer according to claim 9, characterized in that the first filter and the second filter are low-pass filters. Claim 12 A continuous-time linear equalizer according to claim 9, characterized in that the first filter and the second filter have different bandwidths. Claim 13 A continuous-time linear equalizer according to claim 9, characterized in that a load for impedance matching is connected to each of the above T-coils. Claim 14 A continuous-time linear equalizer according to claim 9, wherein the first filter and the second filter have differential inputs and differential outputs. Claim 15 A continuous-time linear equalizer according to claim 9, characterized in that the coupling part has the function of adding or subtracting the output of the first filter and the output of the second filter. Claim 16 A continuous-time linear equalizer according to claim 13, characterized in that the function of adding or subtracting the positive (+) output among the differential outputs of the first filter and the positive (+) output among the differential outputs of the second filter is performed by the coupling part. Claim 17 delete Claim 18 A continuous-time linear equalizer according to claim 9, characterized in that the coupling part has a structure including one or more adders. Claim 19 A continuous-time linear equalizer according to claim 1 or 9, characterized in that an anti-static element is connected to one of the parallel-connected paths.

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