JPH0955770A - Apparatus for transmitting pre-determined frequency response output to unshielded twisted pair medium, waveform shaping circuit therefor and method thereof - Google Patents

Abstract

(57) [Abstract] (Correction) [PROBLEMS] To provide an apparatus for transmitting Manchester code data to an unshielded twisted pair medium. A waveform shaping circuit includes an input terminal, an output terminal, and a plurality of cascade circuit stages, and each cascade circuit stage includes a delay circuit having an input section and an output section, a current source, and a switch circuit. The switch circuit is electrically connected to the output of the delay circuit, is controlled by the delay circuit, and connects a current source to the output terminal, and the delay circuits have the same delay time. , And their total delay time is a half or a multiple of half the bit time of the basic data rate, and each current source is a time sample of a finite impulse response due to the filter transfer function of the waveform shaping circuit. The current value obtained from

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for transmitting a pre-determined frequency response and waveform output to a communication medium, and more particularly to using a waveform shaping circuit and method that can be economically implemented with lower power consumption. , Apparatus for transmitting Manchester code data to unshielded twisted pair media.

[0002]

U.S. Pat. No. 5,267,269 discloses a device for transmitting Manchester code data to an unshielded twisted pair medium. This known device receives non-return-to-zero format data, a sequencer for mode select outputs and step select outputs,
A memory for storing data representing a plurality of pre-determined waveforms,
A multiplexer having a first input connected to the step selection output, a second input connected to the mode selection output, an input bus connected to the memory, and an output bus,
A latch having an input / output end connected to the output bus and an output end for removing data representing a distortion selection waveform;
It is composed of a differential D / A converter having an input end connected to the output end of the latch, an output end of a differential analog current proportional to the selected waveform, and a driver having a low-pass filter.

However, since passive filters have been eliminated in the device, it provides a higher level of integration and saves cost, but still occupies significant silicon area.
Moreover, it consumed a lot of power. Moreover,
Since only the basic bit rate clock can be used, there is a drawback that a circuit for generating a high oversampling clock must be added.

[0004]

SUMMARY OF THE INVENTION In view of the above problems and drawbacks, an object of the present invention is to make Manchester code data into an unshielded twisted pair medium by a waveform shaping circuit and method which can be economically implemented with lower power consumption. It is to provide a device for transmitting.

[0005]

The first feature of the present invention is to:
A waveform shaping circuit comprising an input terminal, an output terminal, and a plurality of cascade circuit stages, wherein each of the cascade circuit stages includes a delay circuit having an input and an output, a current source,
A switch circuit, the switch circuit being electrically connected to the output of the delay circuit to be controlled by the delay circuit and to connect a current source to the output terminal; and the plurality of cascade circuit stages. In
The delay circuit of the first cascade circuit stage is electrically connected to the input terminal, and the inputs of the other delay circuits are electrically connected to the outputs of the adjacent delay circuits, respectively.
The delay circuits have the same delay time, and the current sources have current values obtained from time samples of the finite impulse response by the filter transfer function of the waveform shaping circuit.

The filter transfer function of the waveform shaping circuit has a raised-cosine impulse response, and the total delay time is one half or a multiple of one half of the bit time of the basic code rate. Preferably there is. A second feature of the present invention is that the waveform shaping method obtains a time sample of a finite impulse response by a filter transfer function, and its current value is directly proportional to the time sample,
And a step of providing a plurality of current sources each having a switch circuit, and a delay circuit in which the plurality of delay times are all equal and the total delay time is half the bit time of the Manchester code data, The input section of the first delay circuit receives the Manchester code data, the input sections of the other delay circuits are electrically connected to the output sections of the delay circuits in front of them, and the output sections of the respective delay circuits are And electrically connecting to a switch circuit for controlling a current source to the output terminal, respectively.

A third feature of the present invention is an apparatus for transmitting Manchester code data, which comprises first, second, third and fourth waveform shaping circuits, to an unshielded twisted pair medium, wherein each of the waveform shaping circuits is used. Is composed of an input terminal, an output terminal, and a plurality of cascade circuit stages, of which each of the cascade circuit stages is composed of a delay circuit having an input and an output, a current source, and a switch circuit,
The switch circuit is electrically connected to the output section of the delay circuit, is controlled by the delay circuit, is connected to a current source to the output terminal, and further comprises a first cascade circuit in the plurality of cascade circuit stages. The delay circuit of the road stage is electrically connected to the input terminal, and the input parts of the other delay circuits are electrically connected to the output parts of the delay circuits in front of them, respectively, and each of the delay circuits has a delay time of Are equal,
And, their total delay time is one half of the bit time of Manchester code data, and each current source has a current value obtained from a time sample of a finite impulse response by the filter transfer function of the waveform shaping circuit. It is in.

Further, the first waveform shaping circuit receives Manchester code data, the second waveform shaping circuit receives delayed Manchester code data, and the output of the second waveform shaping circuit. The end is connected to the output of the first waveform shaping circuit, the third waveform shaping circuit receives the inverted Manchester code data, and the fourth waveform shaping circuit is the delayed and inverted Manchester code. The data input is received, and the output end of the third waveform shaping circuit is connected to the output end of the fourth waveform shaping circuit.

The above and other objects of the present invention will be described below.
The features and advantages will be described with reference to the drawings.

[0010]

1 and 2, the waveform shaping circuit of the present invention includes an input terminal (IN) for receiving input data (not shown) and an output terminal (OU).
T) and a plurality of cascade circuit stages 1. Each of the cascade circuit stages 1 includes a delay circuit 1 having an input and an output.
0, a current source 11, and a switch circuit 12. In this embodiment, the input of each delay circuit 10 has first and second input sections (IP, IN), and the output thereof has first and second output sections (OP, ON). In addition, in order to receive the input data, in the plurality of cascade circuit stages 1, the delay circuit 10 of the first cascade circuit stage 1 is electrically connected to the buffer (B) of the input terminal (IN).
The positive signal and the negative signal output from the buffer (B) are input to the first and second input sections (IP, IN) of the first cascade circuit stage 1, respectively. The input sections (IP, IN) of the other delay circuits are electrically connected to the output sections (OP, ON) of the preceding delay circuits, and the delay circuits have the same delay time.

The current source 11 of the cascade circuit stage 1
Is a MOS transistor having a grounded source electrode and a gate electrode connected to a certain current source reference voltage, and the current value is obtained from a time sample of a finite impulse response by a filter transfer function of a waveform shaping circuit. Is. For a causal system, the impulse response should be symmetric with respect to the time axis. In this example, the filter transfer function has a raised cosine impulse response. Therefore, in long transmission media, the minimum alternating symbol (inte
r-symbol) interference occurs. Further, the total delay stage and the number of stage delays depend on the required accuracy of the transfer function.

Further, the switch circuit 12 of each of the cascade circuit stages 1 includes the first and second MOS transistors 121,
The gate electrodes of the first and second MOS transistors 121 and 122 are inverters (INV).
Is electrically connected to the output section (ON, OP) of the delay circuit 10 corresponding to the cascade circuit stage 1, and the drain electrode of the second MOS transistor 122 of each switch circuit 12 is electrically connected to the waveform shaping circuit. Output terminals (OUT) of the respective current sources, and their source electrodes are electrically connected to the drain electrodes of the corresponding current sources 11. The drain electrode of each first MOS transistor 121 is electrically connected to the corresponding gate electrode of the current source 11, and its source electrode is connected to the bias circuit (BS) that supplies the current reference voltage (CSS). Be connected. In this way, each switch circuit 12 is controlled by the corresponding delay circuit 10 and is connected to the current source 11 to the output terminal (OUT).

Next, FIG. 3 consists of first, second, third and fourth waveform shaping circuits (C1, C2, C3, C4) for transmitting Manchester code data to an unshielded twisted pair medium (UTP). It is a block diagram showing the apparatus for doing. The delay circuits 10 of the respective waveform shaping circuits (C1, C2, C3, C4) have equal or equal delay times, and their total delay times are 1/2 or 2 of the bit time of the basic data rate of Manchester code data. It is a multiple of a fraction. In the present embodiment, the buffer of the first waveform shaping circuit C1 receives the Manchester code data (HTD) input, and the buffer of the second waveform shaping circuit C1 receives the delayed Manchester code data (LTD) input. The output end (OUT) of the second waveform shaping circuit C2 and the output end (O) of the first waveform shaping circuit C1 are received.
UT) is connected. The third waveform shaping circuit C3 is used to invert the Manchester code data (L
TD−) input, the fourth waveform shaping circuit C4 is delayed and receives the inverted Manchester code data (HTD−) input, and the output end (OUT) of the third waveform shaping circuit C3. And the fourth waveform shaping circuit C
4 is connected to the output terminal (OUT). here,
All the waveform shaping circuits (C1, C2, C3, C4) are functionally the same. The first and fourth waveform shaping circuits (C
, C4) and the second and third waveform shaping circuits (C2, C4)
3) are complementary to each other in forming the differential output signal for driving the discrete transformer (T). In addition, the first,
The bias level (BIAS1) of the fourth waveform shaping circuit (C1, C4) and the second and third waveform shaping circuits (C
2, C3) and the bias level (BIAS2). Normally, in order to give transmission distortion and reduce the signal jitter at the receiving end far away, the ratio of the current value of the non-delayed Manchester signal to the delayed Manchester signal is set between 5: 1 and 3: 1. It is called the uniform transmission method.

Further, the first and second waveform shaping circuits (C
1, C2) is electrically connected to the first low pass filter (LPF1) at the output end (OUT), and the third and fourth
The output end (OUT) of the waveform shaping circuit (C3, C4) is electrically connected to the second low pass filter (LPF2). In the separation type transformer (T) having the primary coil and the secondary coil, both ends of the primary coil are the first
Low-pass filter (LPF1) and second low-pass filter (L
PF2), the CT (center tap) end of the primary coil is connected to a positive power supply, and the output ends of the secondary coils are connected to unshielded twisted pair medium (UTP), respectively.

It should be noted that the first transistor of the first and fourth waveform shaping circuits (C1, C4) is biased by the first bias voltage (BIAS1), and the second, third The first transistor of the waveform shaping circuit (C2, C3) is to be biased by the second bias voltage (BIAS2). Therefore, the level of pre-compensation is the first and second bias voltages (BIAS1),
(BIAS2). The outputs of the first, second, third and fourth waveform shaping circuits (C1, C2, C3, C4) depend on the shape of the current source, so the output voltage is the reflected signal from the unshielded twisted pair medium (UTP). It is generated by the external load resistance (R1, R2) as the source end point.

[Brief description of drawings]

FIG. 1 is a block diagram showing a waveform shaping circuit of the present invention.

FIG. 2 is a circuit diagram showing a waveform shaping circuit of the present invention.

3 is a block diagram showing an apparatus for transmitting Manchester code data to an unshielded twisted pair medium using the plurality of waveform shaping circuits shown in FIG.

[Explanation of symbols]

 1 Cascade Circuit Stage 10 Delay Circuit 11 Current Source 12 Switch Circuit 121 First MOS Transistor 122 Second MOS Transistor C1 to C4 Waveform Shaping Circuit

Claims (8)

[Claims] 1. An input terminal, an output terminal, and a plurality of cascade circuit stages, each of the cascade circuit stages including a delay circuit 10 having an input section and an output section, and a current source 1.
1 and a switch circuit 12, the switch circuit 12 is electrically connected to the output of the delay circuit 10, is controlled by the delay circuit 10, and connects the current source 11 to the output terminal, and In the plurality of cascade circuit stages, the delay circuit 1 of the first cascade circuit stage 1
0 is electrically connected to the input terminal, the inputs of the other delay circuits 10 are electrically connected to the outputs of the adjacent delay circuits 10, respectively, and each of the delay circuits 10 is
The waveform shaping circuit, wherein the delay times are equal and each of the current sources 11 has a current value obtained from a time sample of a finite impulse response by a filter transfer function of the waveform shaping circuit. 2. The waveform shaping circuit according to claim 1, wherein the filter transfer function has a raised cosine impulse response. 3. A step of obtaining a time sample of a finite impulse response by a filter transfer function, and a step of providing a plurality of current sources 11 each having a current value directly proportional to the time sample and each having a switch circuit 12. All delay times are equal, and the total delay time is half the bit time of Manchester code data.
In the delay circuit, the input section of the first delay circuit is
The Manchester code data is received, and the input sections of the other delay circuits 10 are electrically connected to the output sections of the delay circuits 10 in front of the Manchester code data, and the delay circuit 1 is provided.
The output unit of 0 has a step of electrically connecting to the switch circuit 12 for controlling the current source 11 to the output terminal, respectively, the method for shaping the waveform of Manchester code data. 4. The waveform shaping method according to claim 3, wherein the filter transfer function has a raised cosine impulse response. 5. A first, a second, a third and a fourth waveform shaping circuit (C1, C2, C3, C4), each said waveform shaping circuit having an input terminal, an output terminal and a plurality of cascades. A circuit stage, of which each of the cascade circuit stages has a delay circuit 10 having an input and an output, and a current source 11
And a switch circuit 12, the switch circuit 12 is electrically connected to the output section of the delay circuit 10, is controlled by the delay circuit 10, and connects a current source to the output terminal. In the cascade circuit stage, the delay circuit 10 of the first cascade circuit stage 1 is electrically connected to the input terminal, and the input parts of the other delay circuits are electrically connected in front of each other. , The delay circuits 10 are equal in delay time, and their total delay time is ½ of the bit time of Manchester code data. A current value obtained from a time sample of a finite impulse response due to the filter transfer function of the circuit, and wherein the first waveform shaping circuit is a Manchester code data The second waveform shaping circuit receives the delayed Manchester code data and is connected to the output end of the second waveform shaping circuit and the output end of the first waveform shaping circuit. , The third waveform shaping circuit receives the inverted Manchester code data, the fourth waveform shaping circuit receives the delayed and inverted Manchester code data, and the third waveform shaping An apparatus for transmitting Manchester code data to an unshielded twisted pair medium, wherein an output terminal of the circuit and an output terminal of the fourth waveform shaping circuit are connected. 6. The apparatus of claim 5, wherein the filter transfer function has a raised cosine impulse response. 7. The output terminals of the first and second waveform shaping circuits are electrically connected to the first low-pass filter, and the output terminals of the third and fourth waveform shaping circuits are electrically connected. Second
6. A device according to claim 5, characterized in that it is connected to a low pass filter according to claim 1. 8. In a separation type transformer having a primary coil and a secondary coil, both ends of the primary coil are respectively the first
Connected to a low-pass filter and a second low-pass filter, the CT (center tap) end of the primary coil is connected to a positive power supply, and the output end of the secondary coil is an unshielded twisted pair medium. The device according to claim 7, wherein the device is connected to.