阅读说明：本技术 用于传送多比特位数据的传送器 (Transmitter for transmitting multi-bit data ) 是由 玄昌昊 金秀桓 于 2021-02-22 设计创作，主要内容包括：一种传送器包括：驱动电路系统,被配置成通过根据一个或更多个多比特位数据信号、上拉控制信号和下拉控制信号而控制上拉路径的输出阻抗、下拉路径的输出阻抗或者此二者来驱动耦接到输出节点的通道；驱动控制电路,被配置成根据一个或更多个校准信号和多比特位数据信号、或者根据校准信号和一个或更多个复本多比特位数据信号生成上拉控制信号和下拉控制信号,复本多比特位数据信号复制多比特位数据信号；以及查询表,其存储校准信号的值。(A transmitter comprising: drive circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, in accordance with one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal; a drive control circuit configured to generate a pull-up control signal and a pull-down control signal from one or more calibration signals and the multi-bit data signal, or from a calibration signal and one or more replica multi-bit data signals, the replica multi-bit data signals replicating the multi-bit data signals; and a look-up table storing values of the calibration signal.)

1. A transmitter, comprising:

drive circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, in accordance with one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal;

a drive control circuit configured to generate the pull-up control signal and the pull-down control signal from one or more calibration signals and the multi-bit data signal, or from the calibration signals and one or more replica multi-bit data signals that replicate the multi-bit data signal; and

a look-up table storing values of the calibration signal.

2. The transmitter of claim 1, wherein the drive circuitry comprises:

a first drive circuit configured to drive the channel in accordance with a high bit signal of the multi-bit data signal; and

a second drive circuit configured to drive the channels in accordance with a low bit signal of the multi-bit data signal, an

Wherein the first drive circuit and the second drive circuit are coupled in common to the output node.

3. The transmitter of claim 2, wherein the first drive circuit comprises a plurality of first drive circuit slices that drive the channel according to the high bit signal and are commonly coupled to the output node, an

Wherein the second driving circuit includes a plurality of second driving chips driving the channels by the low bit signal and coupled in common to the output node.

4. The transmitter of claim 3, wherein a ratio of the number of the plurality of first driver dies to the number of the plurality of second driver dies is 2: 1.

5. The transmitter of claim 3, wherein one of the plurality of first drive dies comprises:

a first PMOS transistor having a gate receiving the high bit signal, a source coupled to a first power source, and a drain coupled to a first node;

a first NMOS transistor including a gate receiving the high bit signal, a source coupled to a second power source, and a drain coupled to a second node;

a first adjusting circuit coupled between the first node and a third node, and having an output impedance controlled by the pull-up control signal; and

a second adjustment circuit coupled between the second node and the third node and having an output impedance controlled by the pull-down control signal.

6. The transmitter of claim 5, wherein one of the plurality of first driver chips further comprises a first resistor coupled between the third node and the output node.

7. The transmitter of claim 3, wherein one of the plurality of second drive dies comprises:

a second PMOS transistor including a gate receiving a low bit signal, a source coupled to the first power supply, and a drain coupled to a fourth node;

a second NMOS transistor including a gate receiving the low bit signal, a source coupled to a second power source, and a drain coupled to a fifth node;

a third adjustment circuit coupled between the fourth node and a sixth node and having an output impedance controlled by the pull-up control signal; and

a fourth adjustment circuit coupled between the fifth node and the sixth node and having an output impedance controlled by the pull-down control signal.

8. The transmitter of claim 7, wherein one of the plurality of second driver chips further comprises a second resistor coupled between the sixth node and the output node.

9. The transmitter of claim 2, wherein the drive control circuit comprises a plurality of first selection circuits and a plurality of second selection circuits,

wherein one of the plurality of first selection circuits selects a corresponding one of the calibration signals to generate a pull-up control bit signal from the calibration signal in dependence on the multi-bit data signal or the replica multi-bit data signal, an

Wherein one of the plurality of second selection circuits selects a corresponding one of the calibration signals to generate a pull-down control bit signal from the calibration signal according to the multi-bit data signal or the replica multi-bit data signal.

10. The transmitter of claim 1, further comprising:

a data conversion circuit configured to generate parallel data from input data; and

a first serializing circuit configured to generate the multi-bit data signal by serializing the parallel data.

11. The transmitter of claim 10, wherein the first serializing circuit comprises:

a first serializer configured to generate a high bit signal serialized from the parallel data; and

a second serializer configured to generate a low bit signal serialized from the parallel data.

12. The transmitter of claim 10, further comprising a second serializing circuit configured to generate the replica multi-bit data signal by serializing the parallel data.

13. The transmitter of claim 12, wherein the second serializing circuit comprises:

a third serializer configured to generate a replica high bit signal serialized from the parallel data; and

a fourth serializer configured to generate a replica low bit signal serialized from the parallel data.

14. A transmitter, comprising:

drive circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, in accordance with one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal;

a drive control circuit configured to generate the pull-up control signal and the pull-down control signal as a function of one or more calibration signals and one or more replica multi-bit data signals that replicate the multi-bit data signals;

a data conversion circuit configured to generate parallel data from input data; and

serializing circuitry configured to generate the multi-bit data signal and the replica multi-bit data signal by serializing the parallel data.

15. The transmitter of claim 14, further comprising a look-up table storing values of the calibration signal.

16. The transmitter of claim 14, wherein the serialization circuitry comprises: a first serializing circuit that generates the multi-bit data signal by serializing the parallel data, and a second serializing circuit that generates the replica multi-bit data signal by serializing the parallel data.

17. The transmitter of claim 16, wherein the first serializing circuit comprises:

a first serializer configured to generate a high bit signal serialized from the parallel data; and

a second serializer configured to generate a low bit signal serialized from the parallel data, an

Wherein the second serializing circuit comprises:

a third serializer configured to generate a replica high bit signal serialized from the parallel data; and

a fourth serializer configured to generate a replica low bit signal serialized from the parallel data.

18. The transmitter of claim 14, wherein the drive circuitry comprises:

a first drive circuit configured to drive the channel in accordance with a high bit signal of the multi-bit data signal; and

a second drive circuit configured to drive the channels in accordance with a low bit signal of the multi-bit data signal, an

Wherein the first drive circuit and the second drive circuit are coupled in common to the output node.

19. The transmitter of claim 18, wherein the first drive circuit comprises a plurality of first drive circuit slices that drive the channel according to the high bit signal and are commonly coupled to the output node, an

Wherein the second driving circuit includes a plurality of second driving chips driving the channels by the low bit signal and coupled in common to the output node.

20. The transmitter of claim 18, wherein the drive control circuit comprises a plurality of first selection circuits and a plurality of second selection circuits,

wherein one of the plurality of first selection circuits selects a corresponding one of the calibration signals to generate a pull-up control bit signal from the calibration signal in dependence on the multi-bit data signal or the replica multi-bit data signal, an

Wherein one of the plurality of second selection circuits selects a corresponding one of the calibration signals to generate a pull-down control bit signal from the calibration signal according to the multi-bit data signal or the replica multi-bit data signal.

Technical Field

Embodiments may relate to a transmitter for transmitting multi-bit data.

Background

To transfer data at high speed, multi-bit data is transferred.

For example, a four-level pulse amplitude modulation (PAM-4) signal is a multi-level signal having four levels corresponding to 2-bit data.

Fig. 1 includes an eye diagram showing a comparison of the PAM-2 signal and the PAM-4 signal.

The PAM-2 signal is a binary signal having two levels with a wide gap between the levels.

However, multi-level signals such as the PAM-4 signal are susceptible to noise because the gap between adjacent levels in the vertical direction (here, the difference in voltage levels) is narrower than that of the PAM-2 signal.

Fig. 2 shows a diagram in which the impedance of the termination resistor of the receiver (here, the resistor formed using the on-resistance of the MOSFET) depends on the magnitude of the output voltage.

When multi-bit data is transmitted, the output voltage varies according to the data, and therefore, the impedance of the termination resistor depends on the data.

Therefore, the signal levels may not be uniformly arranged in the eye pattern, thereby deteriorating the linearity of the transmitter. Referring to the eye diagram shown in fig. 2, a first gap between a first pair of adjacent levels (e.g., "11" and "10") may be narrower than a second gap between a second pair of adjacent levels (e.g., "01" and "00"), resulting in degradation of linearity of the transmitter.

Disclosure of Invention

According to an embodiment of the present disclosure, a transmitter may include: drive circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, in accordance with one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal; a drive control circuit configured to generate a pull-up control signal and a pull-down control signal from one or more calibration signals and the multi-bit data signal or from a calibration signal and one or more replica multi-bit data signals, the replica multi-bit data signals replicating the multi-bit data signal; and a look-up table storing values of the calibration signal.

According to an embodiment of the present disclosure, a transmitter may include: drive circuitry configured to drive a channel coupled to an output node by controlling an output impedance of a pull-up path, an output impedance of a pull-down path, or both, in accordance with one or more multi-bit data signals, a pull-up control signal, and a pull-down control signal; a drive control circuit configured to generate a pull-up control signal and a pull-down control signal from one or more calibration signals and one or more replica multi-bit data signals, the replica multi-bit data signals replicating the multi-bit data signals; a data conversion circuit configured to generate parallel data from input data; and serializing circuitry configured to generate a multi-bit data signal and a replica multi-bit data signal by serializing the parallel data.

Drawings

The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate embodiments including the claimed inventive concepts and to explain various principles and advantageous aspects of these embodiments.

Fig. 1 shows a PAM-2 signal and a PAM-4 signal.

Fig. 2 is a graph showing the relationship between the output voltage and the impedance of the termination resistor.

Fig. 3 is a block diagram of a transmitter according to an embodiment of the present disclosure.

Fig. 4A and 4B illustrate the operation of a data conversion circuit according to an embodiment of the present disclosure.

Fig. 5 is a block diagram of a first serializing circuit according to an embodiment of the present disclosure.

FIG. 6 is a block diagram of a second serializing circuit according to an embodiment of the present disclosure.

Fig. 7 is a block diagram of a driving circuit according to an embodiment of the present disclosure.

Fig. 8 is a circuit diagram of a first driving circuit chip according to an embodiment of the present disclosure.

Fig. 9 is a circuit diagram of a second driving circuit chip according to an embodiment of the present disclosure.

Fig. 10 is a circuit diagram of a drive control circuit according to an embodiment of the present disclosure.

FIG. 11 is a look-up table according to an embodiment of the present disclosure.

Fig. 12, 13, 14, and 15 illustrate a calibration operation according to an embodiment of the present disclosure.

Detailed Description

Embodiments will be described below with reference to the drawings. Embodiments are provided for illustrative purposes, but other embodiments not explicitly shown or described are possible. Furthermore, modifications may be made to the embodiments of the present disclosure, which will be described in detail below.

Fig. 3 is a block diagram of a transmitter according to an embodiment of the present disclosure.

The transmitter according to the embodiment of the present disclosure includes a data conversion circuit 10, a serialization circuitry 250, a drive circuit 100, a drive control circuit 300, and a lookup table 400. The serializing circuitry 250 includes a first serializing circuit 210 and a second serializing circuit 220.

The DATA conversion circuit 10 converts the input DATA into DATA having a predetermined form.

In the embodiment of fig. 3, the DATA conversion circuit 10 receives 8-bit parallel DATA and converts it into 4-bit high parallel DATA MSB <3:0> and 4-bit low parallel DATA LSB <3:0 >.

Fig. 4A and 4B each illustrate an operation of a data conversion circuit (e.g., data conversion circuit 10 of fig. 3) according to an embodiment of the present disclosure.

Fig. 4A shows the structure of high parallel data, and fig. 4B shows the structure of low parallel data.

The dotted boxes in fig. 4A represent 4-bit high parallel data MSB <3:0> generated using 8-bit parallel data D0 through D7, and the dotted boxes in fig. 4B represent 4-bit low parallel data LSB <3:0> generated using 8-bit parallel data D0 through D7.

Bit 0 through bit 3 of the low parallel data LSB <3:0> correspond to four data D0, D2, D4, and D6.

Bit 0 to bit 3 of the highly parallel data MSB <3:0> correspond to four data D1, D3, D5, and D7.

Using 8 parallel data from D8 to D15, 8 parallel data from D16 to D23, and 8 parallel data from D24 to D31, respective high parallel data and low parallel data can be generated in the same manner.

Returning to FIG. 3, the first serializing circuit 210 serializes the high parallel data MSB <3:0> and the low parallel data LSB <3:0> to generate a high bit signal MSB and a low bit signal LSB, and the second serializing circuit 220 serializes the high parallel data MSB <3:0> and the low parallel data LSB <3:0> to generate a replica high bit signal RMSB and a replica low bit signal RLSB.

Fig. 5 is a block diagram of a first serializing circuit 210 suitable for use as the first serializing circuit 210 in fig. 3, in accordance with an embodiment of the present disclosure.

The first serializer circuit 210 in fig. 5 includes a first serializer 211 and a second serializer 212.

The first serializer 211 serializes the high parallel data MSB <3:0> to output the high bit signal MSB, and the second serializer 212 serializes the low parallel data LSB <3:0> to output the low bit signal LSB.

Referring to fig. 4A and 4B, the pair of the high bit signal MSB and the low bit signal LSB output from the first serializing circuit 210 are, for example, (D1, D0), (D3, D2), (D5, D4), and (D7, D6). Specifically, the first pair of high bit signal MSB and low bit signal LSB may indicate the first pair of data D1 and D0, respectively, and the second pair of high bit signal MSB and low bit signal LSB may indicate the second pair of data D3 and D2, respectively, and so on.

FIG. 6 is a block diagram of a second serializing circuit 220 suitable for use as the second serializing circuit 220 in FIG. 3, according to an embodiment of the present disclosure.

The second serializing circuit 220 in fig. 6 includes a third serializer 221 and a fourth serializer 222.

The third serializer 221 serializes the high parallel data MSB <3:0> to output the replica high bit signal RMSB, and the fourth serializer 222 serializes the low parallel data LSB <3:0> to output the replica low bit signal RLSB.

Referring to fig. 4A and 4B, the pair of replica high bit signal RMSB and replica low bit signal RLSB output from the second serializing circuit 220 are, for example, (D1, D0), (D3, D2), (D5, D4), and (D7, D6). Specifically, the first pair of replica high-bit signal RMSB and the replica low-bit signal RLSB may indicate the first pair of data D1 and D0, respectively, and the second pair of replica high-bit signal RMSB and the low-bit signal RLSB may indicate the second pair of data D3 and D2, respectively, and so on.

The replica high-bit signal RMSB is a signal that replicates the high-bit signal MSB, and the replica low-bit signal RLSB is a signal that replicates the low-bit signal LSB.

Fig. 7 is a block diagram of a driver circuit (or driver circuitry) suitable for use as the driver circuit 100 in fig. 3, in accordance with an embodiment of the present disclosure.

The driving circuit 100 in fig. 7 drives a channel coupled to the output node NO.

The driving circuit 100 according to the embodiment of the present disclosure includes a first driving circuit 110 and a second driving circuit 120. In an embodiment, the driving circuit 100 may control the first output impedance of the pull-up path or the second output impedance of the pull-down path, or both, according to one or more multi-bit data signals (e.g., the high bit signal MSB and the low bit signal LSB of fig. 3), a pull-up control signal (e.g., the pull-up control signal PU <4:0> of fig. 3), and a pull-down control signal (e.g., the pull-down control signal PD <4:0> of fig. 3). For example, the pull-up path may include equivalent resistors of the first and second driving circuits 110 and 120 (e.g., equivalent resistors R11 and R21 in fig. 12-15), and the pull-down path may include equivalent resistors of the first and second driving circuits 110 and 120 (e.g., equivalent resistors R12 and R22 in fig. 12-15).

The first driving circuit 110 drives a channel according to the high bit signal MSB to provide the output signal OUT, and the second driving circuit 120 drives a channel according to the low bit signal LSB to provide the output signal OUT.

The outputs of the first driver circuit 110 and the second driver circuit 120 are coupled in common at the output node NO.

The output impedances of the first and second driving circuits 110 and 120 are controlled according to the pull-up control signal PU and the pull-down control signal PD. For example, the output impedance of the first driving circuit 110 may be controlled according to the pull-up control signal PU and the pull-down control signal PD, and the output impedance of the second driving circuit 120 may be controlled according to the pull-up control signal PU and the pull-down control signal PD.

The first driving circuit 110 has the same structure and includes a plurality of first driving circuit slices (driving circuit slices) 110-1 to 110-20 coupled in parallel to each other, and the second driving circuit 120 has the same structure and is coupled in parallel to each other and includes a plurality of second driving circuit slices 120-1 to 120-10 coupled in parallel to each other. For example, the first driving circuit 110 may include a plurality of first driving circuit slices 110-1 to 110-20 coupled in parallel to each other, the plurality of first driving circuit slices 110-1 to 110-20 each having substantially the same structure, and the second driving circuit 120 may include a plurality of second driving circuit slices 120-1 to 120-10 coupled in parallel to each other, the plurality of second driving circuit slices 120-1 to 120-10 each having substantially the same structure.

In the embodiment of fig. 7, the number of the first driving circuit pieces 110-1 to 110-20 is 20 and the number of the second driving circuit pieces 120-1 to 120-10 is 10, but the number of each may be different according to the embodiment.

Fig. 8 is a circuit diagram of a first driver circuit slice 110-1 suitable for use as the driver circuit slice 110-1 in fig. 7, according to an embodiment of the present disclosure.

The first driving circuit chip 110-1 in fig. 8 includes a first PMOS transistor MP and a first NMOS transistor MN, to the gates of which the high bit signal MSB is applied.

The first PMOS transistor MP has a source coupled to the first power supply VDDQ and a drain coupled to the first node N1.

The source of the first NMOS transistor MN is coupled to the second power supply VSSQ, and the drain is coupled to the second node N2.

The first driving circuit piece 110-1 further includes a first adjusting circuit 111 and a second adjusting circuit 112.

The first adjusting circuit 111 is coupled between the first node N1 and the third node N3, and the second adjusting circuit 112 is coupled between the second node N2 and the third node N3.

The first adjustment circuit 111 includes a plurality of PMOS transistors MCP0 to MCP4 coupled in parallel between the first node N1 and the third node N3, and a plurality of pull-up control bit signals PU <0> to PU <4> indicating bits of the pull-up control signals PU <4:0> are applied to gates of the plurality of PMOS transistors MCP0 to MCP4, respectively.

The second adjustment circuit 112 includes a plurality of NMOS transistors MCN0 to MCN4 coupled in parallel between the second node N2 and the third node N3, and a plurality of pull-down control bit signals PD <0> to PD <4> indicating bits of the pull-down control signals PD <4:0> are applied to gates of the plurality of NMOS transistors MCN0 to MCN4, respectively.

The pull-up control signal PU <4:0> adjusts the impedance between the first node N1 and the second node N3, and the pull-down control signal PD <4:0> adjusts the impedance between the second node N2 and the third node N3.

That is, the first driving circuit slice 110-1 drives the channel coupled to the output node NO according to the high bit signal MSB, but the output impedance at the output node NO may be controlled according to the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0 >.

The first driving circuit chip 110-1 may further include a first resistor R1 coupled between the third node N3 and the output node NO.

If the first resistor R1 is further included, it is possible to substantially prevent the deterioration of the linearity of the output impedance of the first driving chip 110-1 according to the variation of the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0 >.

Fig. 9 is a circuit diagram of a second driver circuit slice 120-1 suitable for use as the driver circuit slice 120-1 in fig. 7, according to an embodiment of the present disclosure.

The second driving circuit chip 120-1 in fig. 9 includes a second PMOS transistor LP and a second NMOS transistor LN, to the gates of which the low bit signal LSB is applied.

The second PMOS transistor LP has a source coupled to the first power supply VDDQ, and a drain coupled to the fourth node N4.

The source of the second NMOS transistor LN is coupled to the second power supply VSSQ, and the drain is coupled to the fifth node N5.

The second driving circuit piece 120-1 further includes a third adjusting circuit 121 and a fourth adjusting circuit 122.

The third adjusting circuit 121 is coupled between the fourth node N4 and the sixth node N6, and the fourth adjusting circuit 122 is coupled between the fifth node N5 and the sixth node N6.

The third adjustment circuit 121 includes a plurality of PMOS transistors LCP0 to LCP4 coupled in parallel between the fourth node N4 and the sixth node N6, and a plurality of pull-up control bit signals PU <0> to PU <4> indicating bits of the pull-up control signals PU <4:0> are applied to gates of the plurality of PMOS transistors LCP0 to LCP4, respectively.

The fourth adjustment circuit 122 includes a plurality of NMOS transistors LCN0 to LCN4 coupled in parallel between a fifth node N5 and a sixth node N6, and a plurality of pull-down control bit signals PD <0> to PD <4> indicating bits of the pull-down control signals PD <4:0> are applied to gates of the plurality of NMOS transistors LCN0 to LCN4, respectively.

The pull-up control signal PU <4:0> adjusts the resistance between the fourth node N4 and the sixth node N6, and the pull-down control signal PD <4:0> adjusts the impedance between the fifth node N5 and the sixth node N6.

That is, the second driving circuit slice 120-1 drives the channel coupled to the output node NO according to the low bit signal LSB, but the output impedance at the output node NO may be controlled according to the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0 >.

The second driving circuit chip 120-1 may further include a second resistor R2 between the sixth node N6 and the output node NO.

When the second resistor R2 is further included, deterioration of linearity of the output impedance of the second driving circuit 120 can be substantially suppressed according to variations of the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0 >.

Referring back to fig. 7, the outputs of the first and second driving circuit slices 110-1 to 110-20 and 120-1 to 120-10 are commonly coupled to the output node NO.

The level of the output signal OUT supplied from the driving circuit 100 is determined according to the high bit signal MSB and the low bit signal LSB.

At this time, the level of the output signal OUT is adjusted according to the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0> such that the interval between adjacent levels of the output signal OUT can be set to be substantially constant. More specifically, when the output signal OUT has first, second, third, and fourth levels in ascending order, a first interval between the first level and the second level may be substantially equal to a second interval between the second level and the third level and a third interval between the third level and the fourth level. For example, the level separation mismatch Ratio (RLM) of the output signal OUT may be equal to or greater than 0.95, 0.97, or 0.99.

Returning to FIG. 3, drive control circuit 300 may generate pull-up control signals PU <4:0> and pull-down control signals PD <4:0> based on one or more replica multi-bit data signals RMSB and RLSB and one or more calibration signals from look-up table 400. For example, the drive control circuit 300 refers to the lookup table 400 based on the replica high bit signal RMSB and the replica low bit signal RLSB, and provides the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0 >.

The replica high-bit signal RMSB and the replica low-bit signal RLSB are substantially the same signals as the high-bit signal MSB and the low-bit signal LSB.

Accordingly, the drive control circuit 300 may receive the high bit signal MSB and the low bit signal LSB instead of the replica high bit signal RMSB and the replica low bit signal RLSB. Therefore, in the embodiment, the second serializing circuit 220 that generates the replica high-bit signal RMSB and the replica low-bit signal RLSB can be omitted, thereby reducing the circuit area and power consumption of the drive control circuit 300.

In this case, however, deterioration may occur in the high bit signal MSB and the low bit signal LSB supplied to the driving circuit 100 due to a load effect.

When degradation occurs in the signals, it may be beneficial to use the replica high bit signal RMSB and the replica low bit signal RLSB that replicate the high bit signal MSB and the low bit signal LSB, respectively, in the drive control circuit 300.

Fig. 10 is a circuit diagram of a drive control circuit 300 suitable for use as the drive control circuit 300 in fig. 3, according to an embodiment of the present disclosure.

The driving control circuit 300 in fig. 10 includes a plurality of first selection circuits 310 to 314 and a plurality of second selection circuits 320 to 324 outputting pull-up control signals PU <4:0> and pull-down control signals PD <4:0 >. For example, the plurality of first selection circuits 310 to 314 may output a plurality of pull-up control bit signals PU <0> to PU <4>, respectively, and the plurality of second selection circuits 320 to 324 may output a plurality of pull-down control bit signals PD <0> to PD <4>, respectively.

Each of the plurality of first selection circuits 310 to 314 and the plurality of second selection circuits 320 to 324 selects and outputs one of a plurality of signals (e.g., the lookup table 400 in fig. 3) supplied from the lookup table according to the replica high-bit signal RMSB and the replica low-bit signal RLSB.

For example, the first selection circuit 310 receives four signals PU0<0>, PU1<0>, PU2<0> and PU3<0> supplied from the lookup table 400 and outputs a bit 0 signal (or a first pull-up control bit signal) PU <0> of the pull-up control signals PU <4:0> according to the replica high bit signal RMSB and the replica low bit signal RLSB.

The remaining first selection circuits 311 to 314 and second selection circuits 320 to 324 operate in a similar manner to generate signals of corresponding bits of the pull-up control signal PU <4:0> and the pull-down control signal PD <4:0 >.

Fig. 11 is a lookup table 400 suitable for use as lookup table 400 in fig. 3 in accordance with an embodiment of the present disclosure.

The lookup table 400 in fig. 11 stores values of signals PU0<0> to PD3<4> supplied as inputs to the plurality of first selection circuits 310 to 314 and the plurality of second selection circuits 320 to 324 of the drive control circuit 300 as shown in fig. 10.

The signals PU0<0> through PD3<4> having values stored in the lookup table 400 and provided as inputs to the plurality of first selection circuits 310 through 314 and the plurality of second selection circuits 320 through 324 may be referred to as calibration signals.

The values of the calibration signals PU0<0> through PD3<4> stored in the lookup table 400 may be determined by a calibration operation.

Fig. 12, 13, 14, and 15 illustrate a calibration operation according to an embodiment of the present disclosure.

In each of fig. 12 to 15, the left frame corresponds to the first drive circuit 110, and the right frame corresponds to the second drive circuit 120.

As described above, the first and second driving circuits 110 and 120 are commonly coupled to the output node NO.

Among the resistors in the left side frame, the resistance coupled to the first power supply VDDQ corresponds to an output impedance when the first PMOS transistor MP of fig. 8 is turned on in the first driver slice 110-1 (i.e., when the high bit signal MSB is at a low level corresponding to logic 0). This is represented by the 11 th equivalent resistor R11.

Among the resistors in the left side frame, the resistance coupled to the second power supply VSSQ corresponds to an output impedance when the first NMOS transistor MN of fig. 8 is turned on in the first driver chip 110-1 (i.e., when the high bit signal MSB is at a high level corresponding to a logic 1). This is represented by the 12 th equivalent resistor R12.

In this embodiment, the output impedance is determined in consideration of the first resistor R1 of fig. 8.

Among the resistors in the right frame, the resistance coupled to the first power supply VDDQ corresponds to an output impedance when the second PMOS transistor LP of fig. 9 is turned on in the second driver chip 120-1 (i.e., when the low bit signal LSB is at a low level). This is represented by the 21 st equivalent resistor R21.

Among the resistors in the right side frame, the resistance coupled to the second power supply VSSQ corresponds to an output impedance when the second NMOS transistor LN of fig. 9 is turned on in the second driver chip 120-1 (i.e., when the low bit signal LSB is at a high level). This is represented by the 22 nd equivalent resistor R22.

In this embodiment, the output impedance is determined in consideration of the second resistor R2 of fig. 9.

Further, the numbers shown next to the resistors indicate the number of equivalent resistors coupled in parallel between the first power supply VDDQ or the second power supply VSSQ and the output node NO. For example, "R12 × 20" shown in fig. 12 may indicate that 20 equivalent resistors R12 respectively included in the plurality of first driving circuit pieces 110-1 to 110-20 of the first driving circuit 110 are coupled in parallel with each other between the second power supply VSSQ and the output node NO.

In fig. 12 to 15, the termination resistor RT coupled to the output node NO is shown together.

Fig. 12 corresponds to a case where the high bit signal MSB has a first value (e.g., a logic high value of 1) and the low bit signal LSB has a first value (e.g., 1).

At this time, the first and second PMOS transistors MP and LP are turned off, and the first and second NMOS transistors MN and LN are turned on.

Therefore, the 11 th and 21 st equivalent resistors R11 and R21 are not coupled to the output node NO, and the 20 th and 10 th equivalent resistors R12 and R22 are coupled to the output node NO.

In this case, the voltage of the output signal OUT is equal to the voltage of the second power supply VSSQ regardless of the resistance values of the 12 th and 22 nd equivalent resistors R12 and R22.

Fig. 13 corresponds to the case where MSB is 0 and LSB is 0. For example, the high bit signal MSB has a second value (e.g., a logic low value of 0) and the low bit signal LSB has a second value.

At this time, the first and second PMOS transistors MP and LP are turned on, and the first and second NMOS transistors MN and LN are turned off.

Therefore, the 12 th and 22 nd equivalent resistors R12 and R22 are not coupled to the output node NO, and the 20 th and 10 th equivalent resistors R11 and R21 are coupled to the output node NO.

In the embodiment of fig. 13, the voltage of the corresponding output signal OUT is set to about 0.5 times the first power supply VDDQ.

Fig. 14 corresponds to the case where MSB is 1 and LSB is 0. For example, the high bit signal MSB has a first value (e.g., a logic high value of 1), and the low bit signal LSB has a second value (e.g., a logic low value of 0).

At this time, the first and second NMOS transistors MN and LP are turned on, and the first and second PMOS transistors MP and LN are turned off.

Therefore, the 11 th and 22 nd equivalent resistors R11 and R22 are not coupled to the output node NO, and the 20 th and 10 th equivalent resistors R12 and R21 are coupled to the output node NO.

In the embodiment of fig. 14, the voltage of the corresponding output signal OUT is set to about 0.167 times the first power supply VDDQ.

Fig. 15 corresponds to the case where MSB is 0 and LSB is 1. For example, the high bit signal MSB has a second value (e.g., a logic low value of 0) and the low bit signal LSB has a first value (e.g., a logic high value of 1).

At this time, the first and second PMOS transistors MP and LN are turned on, and the first and second NMOS transistors MN and LP are turned off.

Therefore, the 12 th and 21 st equivalent resistors R12 and R21 are not coupled to the output node NO, and the 20 th and 10 equivalent resistors R11 and R22 are coupled to the output node NO.

In the embodiment of fig. 15, the voltage of the output signal OUT corresponding thereto is set to a voltage having about 0.333 times the first power supply VDDQ. Accordingly, a first interval between the first level (e.g., VSSQ) and the second level (e.g., 0.167 × VDDQ) of the output signal OUT may be substantially equal to a second interval between the second level and the third level (e.g., 0.333 × VDDQ) of the output signal OUT and a third interval between the third level and the fourth level (e.g., 0.5 × VDDQ) of the output signal OUT, thereby solving the non-linearity problem of transmitting a multi-level signal (e.g., PAM-4 signal). In other words, the transmitter according to the embodiment may perform output impedance matching in real time based on the received data, thereby ensuring signal integrity of the output signal of the transmitter.

Given the conditions for determining one or more calibration signals as shown in fig. 12 to 15, those skilled in the art can derive these calibration signals through experiments and calculations, and thus detailed descriptions thereof will be omitted.

The determined calibration signal may be stored in a look-up table 400 as shown in fig. 12.

Although the embodiments have been described for illustrative purposes, various changes and modifications are possible.