JPH01143405A - Analog type frequency divider - Google Patents

Abstract

PURPOSE:To attain the frequency division at a required broad frequency band by using a control voltage so as to control a varactor diode thereby controlling the phase of a frequency signal. CONSTITUTION:An input frequency signal inputted from an input terminal 1 is mixed at a mixer 3 by a local signal with frequencies of 1/N and (N-1)/n with respect to the input frequency and frequencyconverted into frequency signals of 1/N and (N-1)/n. The feedback loop consisting of the mixer 3, an amplifier 4 and a varactor diode 5 is subjected to phase control as a positive feedback loop by a capacitance of the varactor diode 6 controlled by a control voltage 6 given externally to the control terminal 7. Thus, the frequency division band is made variable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an analog frequency divider that is applied to frequency synthesizers, modems, measuring instruments, etc. that use a frequency dividing circuit.

[Conventional technology]

FIG. 2 shows an example of a conventional analog frequency divider.

The input frequency signal input from input terminal l is input to mixer 3.
is mixed by a local signal consisting of a frequency of 1/N of the input frequency signal and (N-1)c, and
-1) The frequency is converted into frequency signals of /N and l/N. These signals are amplified by amplifier 4 and fed back to mixer 3 as local signals. At this time, the feedback loop composed of the mixer 3 and the amplifier 4 is set to be a positive feedback loop, and the input frequency is l/
There are N and (N-1)/N frequencies, and a stable frequency division operation is performed.

If the signal in the feedback loop is taken out from the output terminal 2, a frequency signal of 1/N and (N-1)/N of the input frequency signal, that is, a frequency-divided signal will be obtained.

[Problems to be Solved by the Invention] In the conventional analog frequency divider described above, mixer 3. Due to the presence of time delays in the amplifier 4 and the signal transmission path in the loop, the feedback phases are not aligned at all frequencies, so the frequency band in which positive feedback occurs in the feedback loop is limited, and the frequency band in which the frequency is divided is limited. The problem was that it was too narrow.

An object of the present invention is to provide an analog frequency divider that can realize frequency division over a wide frequency band.

[Means for solving problems]

The analog frequency divider of the present invention includes a variable capacitance diode that changes the passing phase of a frequency signal in a feedback loop composed of an amplifier and a mixer, and by controlling the voltage applied to this variable capacitance diode, the feedback loop is This is to control the phase of the signal within and make the frequency band for positive feedback variable.

As a result, the frequency division frequency band becomes variable, and frequency division operation becomes possible in a wide required frequency band.

〔Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows an embodiment of the analog frequency divider of the present invention. The input frequency signal input from the input terminal 1 is mixed in the mixer 3 by a local signal consisting of 1/N of the input frequency and a frequency of (N4)c, and
-1) The frequency is converted into frequency signals of /N and 1/N.

These signals are amplified by an amplifier 4, phase controlled by a variable capacitance diode 5, and then fed back to the mixer 3 as a local signal.

The capacitance of the variable capacitance diode 5 changes depending on the applied voltage, and at this time, the mixer 3. A feedback loop composed of an amplifier 4 and a variable capacitance diode 5 has a capacitance of 1/N of the input frequency and (N-
1) At frequency C, the phase is controlled to form a positive feedback loop.

In the feedback loop, signals with frequencies of 1/N and (N-1)/N of the input frequency exist, and these signals are taken out from the output terminal 2 as a frequency-divided frequency signal.

When the input frequency changes, the external control voltage 6 changes the variable capacitance diode 5 so that the feedback loop becomes positive feedback at frequencies of 1/N and (N-1)/N of the input frequency. By controlling the capacitance, the dividing frequency band can be varied.

Note that FIG. 1 shows one embodiment of the present invention, and even if the variable capacitance diode 5 or the output terminal 2 is installed inside the amplifier 4 (for example, between the stages of the amplifier 4 as a multistage amplifier). A similar effect can be obtained. Furthermore, it is clear that even if the connection direction of the variable capacitance diode 5 is reversed, the same effect can be obtained by reversing the control voltage.

[Effects of the Invention] As explained above, the present invention can change the divided frequency band by controlling the variable capacitance diode using the control voltage and controlling the phase of the frequency signal. An analog frequency divider that can perform frequency division operations in a frequency band can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a block diagram of an example of a conventional analog frequency divider. l...input terminal, 2...output terminal, 3...mixer, 4...amplifier, 5...variable capacitance diode, 6...
...Control voltage, 7...Control terminal.

Claims (1)

[Claims] (1) 1/N frequency of input frequency signal and (N-1)/N
It is equipped with an amplifier that amplifies each signal of a frequency (N is a natural number), and a mixer that multiplies each frequency signal amplified by this amplifier by an input frequency signal, and the output signal of this mixer is fed back to the amplifier. The analog frequency divider that performs frequency operation is characterized by providing a variable capacitance diode that changes the passing phase of each frequency signal, and controlling the voltage applied to the variable capacitance diode to change the divided frequency band. Analog type frequency divider.