JP2825042B2 - U / B conversion circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to U / B (unipolar /
Bipolar) conversion circuit, particularly for converting a unipolar signal used in a transmission device into a bipolar signal
/ B conversion circuit.

[0002]

2. Description of the Related Art Conventionally, this type of U / B conversion circuit is shown in FIG. 2, a unipolar signal 101 having a positive polarity and a unipolar signal 102 having a negative polarity are input to one input terminals of NAND gates 3 and 4, respectively, and a clock signal 103 is supplied to an RC integrating circuit 8 and a buffer gate 9.
The signals are input to the other input terminals of the NAND gates 3 and 4 via a clock input circuit for waveform shaping constituted by the above. The NAND gates 3 and 4 adjust the waveform of the output signal, and input both outputs to the transformer 4. Transformer 4
The two output signals are combined and output as a bipolar signal 104.

The clock signal 103 has a DC node cut by the capacitor 7, and after integrating the waveform by the RC integrating circuit 8, the bias signal is re-biased by the bias circuit 10 and the FAS is applied.
After the waveform is shaped by the buffer gate 9 of the TIC, the NAN
It is output to D gates 3 and 6. In the buffer gate 9, the threshold level changes due to a temperature change in the FAST IC, and the duty of the output clock increases as the temperature of the buffer output increases. It is carried out.

[0004]

In this U / B conversion circuit, a temperature compensating circuit such as a diode is required in order to cope with a temperature change of the threshold of the IC used for the buffer gate. Also, since the input waveform conversion is performed by the RC integration circuit, there is a problem that the waveform of the output signal also changes due to the level fluctuation of the input clock.

[0005]

A U / B conversion circuit according to the present invention comprises two NAND gates for inputting two unipolar signals of positive and negative polarities to one input terminal, respectively, and a clock signal for inputting two waveforms. U / B comprising: a clock input circuit that outputs the signals to the other input terminals of the two NAND gates after shaping the signals; and a transformer that inputs the output signals of the two NAND gates, converts the signals into one bipolar signal, and outputs the signal. In the conversion circuit, the clock input circuit receives the clock signal and cuts a DC component, an LC resonance circuit that converts an output signal of the capacitor into a sine wave, and a duty adjustment for the output signal of the LC resonance circuit. A bias circuit for applying a bias voltage, and an output signal of the bias circuit, The output to the other input terminal of the ND gate and two NAND gates and an inverter in the temperature compensation relationship.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of this embodiment. The input clock signal 103 is input to the LC resonance circuit 8 whose resonance frequency is the same as the frequency of the clock through the capacitor 7 which cuts a DC component, and is converted into a sine wave. The clock signal converted into a sine wave is applied with a bias by a bias circuit 5 and input to the inverter 2 of the FAST IC. This inverter 2 adjusts the clock duty of the output signal. NAND gates 3 and 6 take NANDs of this clock signal and a positive polarity unipolar signal 101 and a negative polarity unipolar signal 102, and a bipolar signal is taken out from both outputs. The clock duty in inverter 2 is adjusted. By doing so, the duty of the bipolar signal can be adjusted.
The bipolar signal outputs of the NAND gates 3 and 6 are input to the transformer 4 to obtain a balanced bipolar signal at the output.

[0008]

As described above, in the U / B conversion circuit of the present invention, the input clock signal is converted into a sine wave by the LC resonance circuit and then the clock is reproduced by the inverter gate. Less susceptible to Further, by canceling the duty change due to the temperature characteristic of the FAST IC due to the use of the FAST IC in the inverter by the NAND gate for punching out data,
This has the effect of stabilizing the output bipolar signal over a wide temperature range without externally performing temperature compensation.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LC resonance circuit 2 Inverter gate (FAST IC) 3 NAND gate (FAST IC) 4 Transformer 5 Bias circuit 6 RC integration circuit 7 Capacitor

Claims (1)

(57) [Claims] 1. Two NANs for inputting two unipolar signals of a positive polarity and a negative polarity to one input terminal, respectively.
A D gate, a clock input circuit for inputting a clock signal, shaping the waveform and outputting the resulting signal to the other input terminal of the two NAND gates, and an output signal of the two NAND gates for conversion into one bipolar signal A U / B conversion circuit including a transformer for inputting and outputting the clock signal, a capacitor for cutting a DC component, an LC resonance circuit for converting an output signal of the capacitor into a sine wave, and an LC resonance circuit for converting the output signal of the capacitor into a sine wave. A temperature compensation relationship between a bias circuit that applies a bias voltage for duty adjustment to an output signal of the circuit and the two NAND gates that invert the output signal of the bias circuit and output the inverted signal to the other input terminal of the two NAND gates A U / B conversion circuit comprising: an inverter according to claim 1.