JPS6267903A - Frequency doubler circuit - Google Patents

Abstract

PURPOSE:To accurately obtain a double frequency signal over a wide frequency region up to a high frequency of nearly GHz irrespective of kinds of an input signal waveform of detecting a 0-phase location and a pi-phase location in the input signal waveform so as to extract a double frequency component. CONSTITUTION:Wnen an input sine wave signal (g) having a frequency (f) (period T) is inputted to an input terminal 11, the input signal (g) is given to a waveform shaping circuit 12, where the signal is waveform-shaped into a pulse signal whose signal level is inverted in the signal waveform by one period at the 0-phase locattion and the pi-phase location. Pulse signals (j), (k) from pulse generating circuits 13, 14 ar synthesized by an OR circuit 15, from which an OR signal (l) is inputted to a signal input terminal of a variable band-pass filter 16. The fraquency of an output signal outputted from the variable band- pass filter 16 is varied as a voltage value EF of a voltage signal (m) outputted from a frequency voltage conversion circcuit 17 and an output signal (n) having a frequency 2f being twice the frequency of the input signal (g) is obtained from an output terminal 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency doubling circuit that doubles the frequency of an input signal.

[Prior Art 1] For example, in a synthesizer, a signal with an extremely stable frequency obtained from a crystal oscillator or the like is converted into a signal having a stable desired frequency by using a frequency synthesizer. One such frequency synthesizer is a frequency doubling circuit that doubles the frequency of an input signal.

Conventionally, such a frequency doubling circuit is configured as shown in FIG. 5, for example. That is, the input signal of frequency f (period T) input from input terminal 1 is sent to full-wave rectifier circuit 2.
The signal is input to and undergoes full-wave rectification. The full-wave rectified signal output from the full-wave rectifier circuit 2 is input to the signal input terminal of the variable band-pass filter 3. On the other hand, the input signal input from the input terminal 1 is also input to the frequency-voltage conversion circuit 4. Then, from this frequency-voltage conversion circuit 4, an electric signal proportional to the frequency f of the input signal is input to the pass frequency control I terminal of the variable band pass filter 3. In this variable bandpass filter 3, the pass frequency of the signal input to the signal input terminal changes in response to changes in the voltage input to the pass frequency control terminal. Therefore, by changing the voltage value input to the pass frequency control terminal, the frequency f' of the output signal of the variable band pass filter 3 can be subdivided.

When a sine waveform input signal a having a frequency f is input to the input terminal 1 of the frequency doubling circuit J3 configured as described above, for example, as shown in FIG. The rectifier circuit 2 performs high-wave rectification to obtain a full-wave rectified signal. Therefore, this full-wave rectified signal is the input signal a
In addition to the frequency component of f which is the fundamental frequency of , it has a frequency component of twice the frequency 2f. This full-wave rectified signal is then input to the signal input terminal of the variable bandpass filter 3.

Furthermore, since the input signal a is input to the frequency-voltage conversion circuit 4, a voltage signal C having a voltage Ep proportional to the frequency f of the input signal a is applied to the pass frequency control terminal of the variable bandpass filter 3. . In this state, the output voltage EF of the frequency-voltage conversion circuit 4 is adjusted so that the passing frequency of the variable bandpass filter 3 becomes the frequency 2f included in the full-wave rectified signal. Therefore, if the bandwidth of the passing frequency of the variable band-pass filter 3 is narrow enough to exclude adjacent frequency components (f, 3f, 4f,...), this variable band-pass filter 3
The output signal d output from the output terminal 5 to the output terminal 5 has a sine waveform having a frequency of 2f.

Therefore, the frequency of the output signal d output from the output terminal 5 is twice the frequency of the input signal input to the input terminal 1. When the frequency f of the input signal a changes, the voltage signal C of the frequency-voltage conversion circuit 4 also changes in proportion to the change in the frequency f indicated by #, so the variable bandpass filter 3
The passing frequency of also changes in proportion to the change in the frequency f of the input signal a. As a result, the input signal a is always output from output terminal 5.
An output signal @d having twice the frequency is obtained.

[Problems to be Solved by the Invention] However, the frequency doubling circuit i configured as described above has the following problems.

That is, the input signal a is subjected to high frequency rectification in order to extract from the input signal a a frequency component twice the frequency f of this input signal @a. Therefore, when the input signal a is not a sine waveform but a rectangular waveform, it is necessary to first convert this rectangular waveform into a sine wave signal and then input it to the input terminal 1 and perform the logical sum. Therefore, a separate conversion circuit is required to convert the rectangular wave signal into a rein wave signal.

In addition, when the frequency f of the input signal @a becomes a high frequency, for example, about G1-1z, the waveform distortion that occurs during rectification, that is, the ratio of the width of each rectifying element connected in a bridge increases, and the fundamental frequency Since the frequencies of the desired high frequency component and the desired high frequency component are close to each other, there is a possibility that the desired high frequency component is included in the bandwidth of the pass frequency of the variable band pass filter 3. This is GH
This is because it is difficult to obtain a variable bandpass filter 3 with a large ratio of passing/blocking characteristics in a frequency region around the Z band. Therefore, the frequency doubling circuit shown in FIG. 5 does not operate as an accurate doubling circuit in a high frequency region such as the GH2 band.

The present invention has been made based on these circumstances, and its purpose is to detect a predetermined level of an input signal waveform and generate a rectangular wave, that is, to detect a predetermined level of an input signal waveform and generate a rectangular wave. ) and the π phase position. To provide a frequency doubling circuit that can accurately obtain a double frequency signal over a wide frequency range up to a high frequency of about GHz, regardless of the type of input signal waveform, by extracting the double frequency component in this manner. There is a particular thing.

Means for Solving Problem 1] The frequency doubling circuit of the present invention includes a waveform shaping circuit that shapes an input signal and outputs a rectangular waveform signal, and a waveform shaping circuit that shapes an input signal and outputs a rectangular waveform signal, and a frequency doubling circuit of the present invention. a first pulse generating circuit that outputs a pulse with a predetermined time width when the signal changes from low level to high level; a second pulse generating circuit that outputs a pulse having the same width as the first pulse generator;
The variable bandpass filter is controlled by the output voltage of the frequency-voltage conversion circuit so as to pass a signal having a frequency twice that of the input signal outputted by the first circuit.

[Operation] With the frequency doubling circuit configured as described above, the input signal input from the input terminal is converted by the waveform shaping circuit into a pulse signal whose signal level changes at a predetermined level of the input waveform. Then, the above-mentioned signal is generated by the first and second pulse generating circuits. As a result, the amusing circuit outputs two pulses that are synchronized with the times when the signal waveform rises and falls at a predetermined level within one cycle of the input signal, and a signal with twice the frequency component of the input signal is output from the variable band. Input to pass filter. Since a voltage proportional to the frequency of the input signal outputted from the frequency-voltage conversion circuit is applied to the pass frequency control terminal of this variable band-pass filter, by adjusting the output voltage level of this frequency-voltage conversion circuit, An output signal having twice the frequency of the input signal is output from the variable bandpass filter.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a frequency doubling circuit according to an embodiment. In the figure, reference numeral 11 denotes an input terminal to which an AC input signal is input, and this input terminal 11 is connected to an input terminal of a waveform shaping circuit 12. This waveform shaping circuit 12 outputs a pulse signal whose signal level is inverted between the O phase position and the π phase position in one cycle of the signal waveform of the AC input signal.

Specifically, the signal level is inverted when the waveform crosses the voltage OV line. The non-inverting output terminal Q of this waveform shaping circuit 12 is connected below the trigger terminal of the first pulse generating circuit 13 formed by a one-shot multivibrator, and the inverting output terminals are connected to the first pulse generating circuit 13 formed by a one-shot multivibrator. It is connected to the trigger input terminal of a second pulse generating circuit 14 having the same configuration as that of the second pulse generating circuit 14. These first and second pulse generation circuits 13 and 14 are configured so that the signal input to the trigger terminal T is L.
In synchronization with the rising time from the level to the H level, a pulse signal that becomes 1-level from the rising time for a predetermined time To determined by the time constants of the resistor and the capacitor is output from the output terminal Q. Note that the value of the predetermined time To is set to a value of about 1/2 of the period corresponding to the maximum frequency of the input signal input to the input terminal 11.

The output terminal of this path 6 to 15 is connected to the signal input terminal of a variable bandpass filter 16.

Further, the input terminal 11 is connected to an input terminal of a frequency-voltage conversion circuit 17, and an output terminal of this frequency-voltage conversion circuit 17 is connected to a passing frequency control terminal of the variable bandpass filter 16.

This variable bandpass filter 16 outputs from the signal output terminal only the frequency component corresponding to the voltage input to the pass frequency control terminal among the frequency components of the signal input from the signal input terminal. A signal output terminal of this variable bandpass filter 16 is connected to an output terminal 18 of this frequency doubling circuit.

The operation of the frequency doubling circuit configured as described above will be explained using the time chart shown in FIG.

That is, when an input signal Q of a sine wave with a frequency (period T) is inputted to the input terminal 11, this input signal Q is inputted into the waveform shaping circuit 12 by the O phase of the signal waveform for one period of the human input signal q. The waveform is shaped into a pulse signal whose signal level is inverted at the position and the π phase position. Then, there is a pulse signal whose signal level is symmetrical to each other from the Q and terminals, i
is output. Therefore, the pulse signal output from the Q terminal rises from the level to the H level at the O(2π) phase position of the input signal q, and the pulse signal output from the 0 terminal rises from the L level at the π phase position of the input signal 0. Get up to H level.

The first and second pulse generating circuits 13 and 14, to which the pulse signals RI and 1 are inputted to the trigger terminals, generate signals in synchronization with the rise time (0 phase position, π phase position) of the input pulse signals RI and 1, respectively. A pulse signal j that rises and remains at an H level for a predetermined time To.

The signal J is synthesized in one circuit 15, and the logical sum signal ℃
and is input to the signal input terminal of the variable bandpass filter 16. Therefore, as shown in the figure, the signal waveform of the OR signal C includes two pulse waveforms each having a predetermined time To width from the O phase position and the π phase position within one cycle T of the input signal 0. That is, this OR signal includes a frequency 2f component that is twice the frequency f of the human input signal 0.

Since the frequency of the output signal outputted from the variable bandpass filter 16 is varied by the voltage value EF of the voltage signal m outputted from the frequency-voltage conversion circuit 17, the output voltage level of the frequency-voltage conversion circuit 17 is changed by the signal input. Adjustments are made so that the 2f frequency component of the OR signal Q input to the terminal is output.

Therefore, an output signal n having a frequency 2f twice that of the input signal Q is obtained from the output terminal 18.

Note that the DC voltage signal m output from the frequency-voltage conversion circuit 17 is a voltage fii proportional to the frequency f of the input signal Q.
E F, so once the output signal level is adjusted as described above, there is no need to readjust it even if the frequency f of the input signal q changes.

FIG. 3 shows the signal waveforms of each part when the frequency of the input signal q changes to f/2 (period 2). When the frequency of the input signal Q becomes 1/2, the variable bandpass filter 16 The frequency component included in the logical sum signal a input to the signal input terminal of is also (1/2)x2f, that is, f, and the voltage value of the voltage signal m output from the frequency-voltage conversion circuit 17 also corresponds to the frequency f. The voltage value will be Therefore, the variable bandpass filter 16 passes the signal of frequency f, and as a result, the frequency of the output signal n, which is multiplied by the output terminal, also becomes f.

In this way, an output signal n having a frequency 2f twice the frequency f of the input signal 0 input to the input terminal 11 is always outputted to the output terminal 18.

Then, when the frequency f of the input signal q changes, the output signal n
The frequency of also changes in proportion to the change in the frequency of the input signal 0.

If the frequency doubling circuit is configured as in the present invention,
The waveform of the input signal 0 may not be a sine wave waveform as shown in FIG. 2, but may be a distorted waveform, or may be at a point other than the zero level point of the sine waveform.

Furthermore, even if the signal waveform is rectangular with a period T (frequency f) as shown in FIG. For each pulse signal whose signal level is inverted at the phase position, + is obtained.

Therefore, it is possible to apply not only sine wave signals but also various signal waveforms.

In addition, since the full-wave rectifier circuit used in conventional circuits is not used, there is no need to consider the adverse effects of the aforementioned waveform distortion and unbalance of the full-wave rectified waveform due to full-wave rectification processing, so high frequencies of around GHz Accurately double frequency signals can be obtained over a wide frequency range up to

[Effects of the Invention] As explained above, according to the frequency doubling circuit of the present invention, the O phase position and the π phase position in the input signal waveform are detected to extract twice the frequency component. Therefore, regardless of the type of input signal waveform, a wide frequency signal up to a high frequency of the order of GHZ = 14 - exactly twice the frequency signal can be obtained in the range of several heads.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing a frequency doubling circuit according to an embodiment of the present invention, FIGS. 2 to 4 are time charts showing the operation, and FIG. 5 is a conventional frequency 11 input terminal,
12... Waveform shaping circuit, 13... First pulse generation circuit, 14... Second pulse generation filter, 17...
・Frequency voltage conversion circuit.

Claims (1)

[Claims] a waveform shaping circuit (12) that shapes an input signal and outputs a rectangular waveform signal; when the rectangular waveform signal changes from a high (H) level to a low (L) level, a pulse of a predetermined time width is generated; a first pulse generating circuit (13) that outputs;
a second pulse generating circuit (14) that outputs a pulse having substantially the same width as the predetermined time width when the rectangular wave signal changes from a low level to a high level; the first and second pulse generating circuits; an OR circuit (15) that ORs pulse signals output from the input signal and outputs a signal having twice the frequency component of the input signal; and a frequency-voltage conversion circuit that outputs a voltage corresponding to the frequency of the input signal. (17); connected to the OR circuit and the frequency-voltage conversion circuit;
a frequency doubling circuit comprising a variable bandpass filter (16) controlled by the output voltage of the frequency-voltage conversion circuit so as to pass a signal having a frequency twice that of the input signal outputted by the OR circuit; .