JPH0281513A - Frequency multiplier circuit - Google Patents

Abstract

PURPOSE:To attain multiplication of a duty cycle 50% with simple constitution by constituting the circuit with a 90 deg. phase shifter, a waveform shaping circuit and a logic circuit having an exclusive OR function. CONSTITUTION:The phase of an input signal is shifted by 90 deg. at a phase shifter 2, the input signal and the output of the phase shifter 2 are inputted respectively to the 1st and 2nd waveform shaping circuits 3, 4 where the signal is subject to waveform shaping at zero cross points and a rectangular wave signal whose duty factor is 50% is outputted. The rectangular wave signals are waveforms whose phases are shifted by 90 deg., inputted to a logic circuit 5, where exclusive OR is taken and a pulse signal whose frequency is doubled with a duty factor of 50% is outputted. Thus, the frequency multiplier circuit is realized with simple circuit constitution and a pulse signal with a frequency double by a duty factor 50% is surely obtained by using the 90 deg. phase shifter 2.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a frequency multiplier circuit.

(B) Conventional technology Conventionally, when frequency-multiplying an AC signal as shown in A in Fig. 4 to obtain a clock signal, etc., the input AC signal A as shown in Fig. 3 is The rectifier circuit 31 performs full-wave rectification to output the waveform signal shown in B in FIG. I'm getting a signal.

(c) Problems to be Solved by the Invention The conventional frequency multiplier circuit described above uses a full-wave rectifier circuit, which makes the circuit complex, and the duty cycle of the obtained pulse signal is not 50%. In order to obtain 50%, it is necessary to add an extra circuit such as a one-shot multi-circuit, which causes the problem that the circuit becomes even more complicated.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a frequency multiplier circuit capable of multiplying the duty cycle by 50% with a simple configuration.

(d) Means and operation for solving the problems The frequency multiplier circuit of the present invention includes a phase shifter (2) that receives an input signal and shifts the phase by 90 degrees, and a phase shifter (2) that receives the input signal and shifts the phase by 90 degrees. A first waveform shaping circuit (3) that shapes a waveform and outputs a rectangular wave signal, and a second waveform shaping circuit (3) that receives the output of the phase shifter, shapes the waveform at a zero cross, and outputs a rectangular wave signal. 4)
and a logic circuit (5) which receives the outputs of the first and second waveform shaping circuits and outputs the exclusive OR of both of them.

In this frequency multiplier circuit, the phase of the input signal is changed to 9 by the phase shifter.
0° phase shifted. Then, the input signal and the output of the phase shifter are input to the first and second waveform shaping circuits, respectively, where the waveforms are shaped by the zero cross, and a rectangular wave signal with a duty of 50% is output. These rectangular wave signals have waveforms with a phase shift of 90' from each other, and are input to a logic circuit, exclusive ORed, and a pulse signal whose frequency is doubled with a duty of 50% is output. .

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 1 is a circuit diagram of a frequency multiplier circuit showing one embodiment of the present invention. This frequency multiplier circuit includes a phase shifter 2 that shifts the phase of the input signal input to the input terminal 1 by 90 degrees, a first waveform shaping circuit 3 that shapes the waveform of the input signal A at zero crosses, and a phase shifter 2 that shifts the phase of the input signal input to the input terminal 1 by 90 degrees. A second waveform shaping circuit 4 that also shapes the waveform of the output of the device 2 with a zero cross, and the outputs of the first waveform shaping circuit 3 and the second waveform shaping circuit 4 are connected to the input,
It is comprised of a logic circuit 5 which outputs the exclusive OR of both the inputs from an output terminal 6.

The phase shifter 2 is constructed by cascading two stages of a 45° phase shift circuit consisting of a resistor R and a capacitor C, but this phase shift circuit shifts the phase by 90° in one or three stages. It may also be a circuit.

In the frequency multiplier circuit configured as described above, when an AC input signal shown in A in FIG. 2 is applied to all input terminals 1, the phase of this signal is shifted by 90 degrees by the phase shifter 2, A waveform signal shown in FIG. 2B is output. Since the phase has been shifted by 90 degrees, the signal B output from the phase shifter 2 has a phase difference of 90 degrees with respect to the input signal A. The input signal A is inputted to the first waveform shaping circuit 3, and the output of the phase shifter 2, that is, the signal B, is inputted to the second waveform shaping circuit 4, where the waveform is shaped at the zero cross, and the first waveform is The shaping circuit 3 outputs a rectangular wave signal shown in C in FIG. 2, and the second waveform shaping circuit 4 outputs a rectangular wave signal shown in D in FIG. Signal C and signal R have a phase difference of 90°, similar to the relationship between signal A and signal B. Signal C and signal RI are
The signal is input to the logic circuit 5 and subjected to logical processing. Since signal C and signal A have a phase difference of 90°, input signal A is
At 0°, the signal C is “H” (high), while the signal C is “L” (low), and the two are logically inconsistent, so the logic circuit 5 outputs the output terminal 6 due to the exclusive OR function. to “H”
(See E in FIG. 2).Next, when the input signal A is 90° to 18°, both the signal C1 and the signal C1 are "HII", and both logics fail, so the logic circuit 5 "L" is output to the output terminal 6 (see E in FIG. 2). Subsequently, at 180 to 270 degrees of input signal A, signal C is "L", while signal A is "H", and the two are logically inconsistent. Therefore, the logic circuit 5 outputs "H" to the output terminal 6.
(See E in Figure 2).

Further, at 270 to 360 degrees to the input signal, the signal C1 is also L'', both are logic-defective, and the logic circuit 5 outputs °L'' to the output terminal 6 (E in Fig. 2). ).Then, the same operation is repeated as time passes.As a result, the output signal E becomes the phase 9 of the input signal A.
“F Bi and °′L°” are reversed every 0°. That is, it is output as a pulse signal with a duty of 50% and a frequency twice that of the input signal.

(f) Effects of the invention According to this invention, a 90° phase shifter and a waveform shaping circuit,
The circuit is configured with a logic circuit having an exclusive OR function, and a full-wave rectifier circuit is not used, so a frequency multiplier circuit can be realized with a simple circuit configuration. Moreover, by using a 90° phase shifter, 2
It is possible to reliably obtain a multiplied pulse signal.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a frequency multiplier circuit showing an embodiment of the present invention, Fig. 2 is a signal waveform diagram of each part to explain the operation of the frequency multiplier circuit of the same embodiment, and Fig. 3 is a conventional frequency multiplier circuit. FIG. 4, a block diagram showing a schematic configuration of the circuit, is a signal waveform diagram of each part for explaining the operation of the frequency multiplier circuit. 2: Phase shifter, 3: First waveform shaping circuit, 4: Second waveform shaping circuit, 5: Logic circuit, 6: Output terminal. Patent applicant: ROHM Co., Ltd. Agent: Patent attorney: Shigeru Nakamura

Claims (1)

[Claims] (1) A phase shifter that receives an input signal and shifts the phase by 90°; a first waveform shaping circuit that receives the input signal, shapes the waveform at a zero cross, and outputs a rectangular wave signal; a second waveform shaping circuit that receives the output of the phase converter, shapes the waveform with a zero cross, and outputs a rectangular wave signal; and a second waveform shaping circuit that receives the outputs of the first and second waveform shaping circuits as inputs, and excludes both inputs. A frequency multiplier circuit consisting of a logic circuit that outputs a logical sum.