KR930002784Y1 - Bi-phase mudulation circuit for digital audio interface - Google Patents

Abstract

No content.

Description

Bi-Phase Modulation Circuit for Digital Audio Interface

1a to b are general pulse waveform diagrams before and after general bi-phase modulation.

2 is a circuit diagram showing a bi-phase modulation circuit used in the digital audio interface according to the present invention.

3A to 3G are pulse waveform diagrams of respective parts of FIG. 1.

* Explanation of symbols for main parts of the drawings

1: Clock signal input terminal

2: Digital data signal input stage to be bi-phase modulated

10: 1D flip-flop 20: 2D flip-flop

30: 3D flip-flop A: Clock signal delay unit

B: Bi-phase modulator G1, G2, G4: 2 input and gate

G3: Inverter G5: 2-input OA gate

The invention relates to the interface of digital audio equipment, and more specifically, to the digital output of digital audio equipment such as compact discs (CDs) or digital audio tapes (DATs). Bi-Phase modulation circuit used in the digital audio interface to interface.

In general, the digital output of a digital audio device is composed of a “NRZ” (Not Return To Zero) signal as shown in FIG. 1A. However, the “NRZ” signal cannot be used as it is in compact discs or digital audio tapes. It must be converted to digital data in phase-converted format. The bi-phase conversion is a waveform inverted at the change point of the data when the digital data is "0" and inverted at the change point of the data and the center of the data when "1" is shown in FIG. Because of the different digital audio interface data standards used in Pulse Code Modulation (“PCM”) audio tapes (DAT), the operation of the equipment is not correct when bi-phase modulation is not performed according to the interface format. There was a problem.

The present invention solves this problem, and an object of the present invention is to provide a bi-phase modulation circuit used in a digital audio interface for bi-phase modulating a PCM decoded digital output to interface to a digital audio device. have.

A feature of this invention for achieving this object is connected to a clock signal input terminal, and receives a clock signal from a clock signal input terminal from a clock signal input terminal, and is connected to an input terminal of a clock signal inputted from the clock signal input terminal. An inverter for inverting a clock signal of the second signal; a second D flip-flop connected to an uninverted output terminal of the first D flip-flop and receiving and delaying an inverted clock signal by the inverter; An AND gate for ANDing an uninverted output signal of the flip-flop, and an AND gate for connecting the output terminal of the first and second D-FLIP flops to AND the inverted output signal of the first and second D-Flip flops. A clock signal delay unit for delaying a clock signal from the clock signal input terminal, and connected to the AND gate to output the AND gate. An AND gate that multiplies a call with a digital data signal to be bi-phase modulated, an OG gate connected to the AND gate, and receiving an input signal from the AND gate, and connected to the OG gate to output an output signal of the OG gate. And a bi-phase conversion circuit used for a digital audio interface unit composed of a bi-phase modulator of a 3D-flip-flop that receives the bi-phase converted digital signal.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 2 is a circuit diagram showing a bi-phase modulation circuit for use in the digital audio interface according to the present invention. The clock signal delay unit A is provided to a clock signal delay unit A for delaying a clock signal. The bi-phase modulator (B) for bi-phase modulation the signal from the is made is connected.

The clock signal delay unit A receives a clock signal from the clock signal input terminal 1 to the clock terminal CK1 and outputs a first divided signal of a clock signal input thereto. A second D flip-flop 20 for delaying a signal is connected to an output terminal (a) of the (10) and an inverter G3 for inverting a clock signal from the clock signal input terminal 1 is connected to the second D-flip. The first and second D flip-flops 10 and 20 are connected to the clock terminal CK2 of the flop and the AND gate G1 whose output becomes “high” only when both input signals are “high”. The inverted signal of the first and second flip-flops 10 and 20, connected to the uninverted signal Q output terminals a and b ) And gate (G2) is connected to the output terminals (h), (i).

On the other hand, the bi-phase modulator B has an AND gate G4 for ANDing the output signal of the AND gate G2 and the digital data signal to be bi-phase modulated with the output terminal d of the AND gate G2. The OA gate G5 connected to the digital data signal input terminal 2 to be bi-phase modulated and whose output is "high" except when two signals of two different input signal values are both "low" states is described above. A D-flip-flop 30 connected to the AND gates G4 and G2 and outputting a bi-phase converted digital signal is connected to the oragate G5.

In more detail, this design configured as described above is first inputted to the clock terminal CK1 of the first D flip-flop 10 which is twice the transmission rate of digital data. The non-inverted output value of the first D flip-flop 10 is a value obtained by dividing the clock signal input to the first D flip-flop 10 by two divisions. This waveform is shown in FIG.

The two-divided data output is input to the 2D flip-flop 20 and delayed as shown in the waveform of FIG. 3b. In this way, when the inverted output signals of the first and second D flip-flops 10 and 20 are ANDed by the AND gate G2, the waveform of FIG. 3D is obtained. When this is done by the digital data and the AND gate G4 to be bi-phase modulated, a waveform as shown in FIG. 3E is output. The waveform of (e) becomes a waveform at which the pulse comes out at the last part when the digital data is "1". In addition, when the uninverted output signals of the first and second D-flip flops 10 and 20 are ANDed by the AND gate G1, a waveform similar to that of FIG. 3E is obtained.

In this way, if the sum of the waveforms (e) and (c) of FIG. 3 is ORed together, a waveform as shown in (f) is generated and the waveform of (f) is transferred to a flip-flop such as the 3D-flip-flop 30. When the input signal is input to the clock signal input terminal, a bi-phase converted digital waveform is output as shown in (g).

As described above, this design makes the circuit simple and cost-effective by simply configuring a bi-phase modulation circuit, which is a digital audio conversion standard, using a small amount of flip-flops and gates and using the digital interface unit.

Claims (1)

A first D flip-flop (10) connected to the clock signal input terminal (1) for receiving a clock signal from the clock signal input terminal (1) and outputting a divided signal of the input clock signal; An inverter (G3) connected to (1) to invert the clock signal from the clock signal input terminal (1), and to an uninverted output terminal (a) of the first D flip-flop and connected to the inverter (G3). 2D-flip-flop 20 for receiving and delaying the clock signal inverted by < RTI ID = 0.0 >) < / RTI > and an AND gate for ANDing the uninverted output signals of the first, 2D-flip-flop 10, 20. G1) and the output terminals (h) and (i) of the first and second D-flop flops 10 and 20 to connect the first and second D-flop flops 10 and 20 to each other. A clock signal delay section A for providing an AND gate G2 for inverting the inverted output signal and delaying a clock signal from the clock signal input terminal 1; An AND gate (G4) connected to the drain gate (G2) to multiply the output signal of the AND gate (G2) by a digital data signal to be bi-phase modulated, and connected to the AND gates (G1) and (G4). Oa gate (G5) to receive the signal from the gate (G1), (G4) and the digital signal that is connected to the ora gate (G5) and receives the output signal of the Oagate (G5) to the bi-phase conversion A bi-phase modulation circuit for use in a digital audio interface unit comprising a bi-phase modulation unit (B) comprising an output 3D flip-flop (30).