JP2002164784A - Frequency generator circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a stable operation of a PLL circuit even while reducing the number of parts. SOLUTION: A comparison frequency (b) outputted from a frequency divider 2 is controlled so as to be X times as long as a channel interval dF by making the frequency-diving number R in the frequency divider 2 to be R=a/(dF×X) (X is a natural number) and also making the denominator of the frequency diving number to be X in a fraction frequency divider 8 at the time when a receiving station transmission frequency signal is generated in the case a reference frequency outputted from a reference oscillator 1 is defined as (a) and the channel interval is defined as dF, the comparison frequency (b) outputted from the frequency divider 2 is also controlled so as to be b=dF×X×(K+1)/K by making the frequency dividing number R in the frequency divider 2 to be R=a(K+1)/(dF×K×X) and also making the denominator of the frequency dividing number to be X in the fraction frequency divider 8 in the case the frequency dividing number is defined as K in a frequency divider 9 when a transmission carrier wave frequency signal is generated, and the current of a charge pump 4 is further controlled so as to be (K+1)K times as high as the current at the time when the receiving station transmission frequency signal is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency generating circuit, and more particularly to a frequency generating circuit used for a portable telephone.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration example of a frequency generating circuit used in a conventional portable telephone.

In this conventional example, as shown in FIG. 4, a reference oscillator 101 that outputs a reference frequency a, and a reference frequency a output from the reference oscillator 101 are divided by 1 / R and output as a comparison frequency b. Frequency divider 102, voltage controlled oscillator 106 for outputting oscillation frequency c, voltage controlled oscillator 106
A frequency divider 208 that divides the oscillation frequency c output from the oscillating frequency c by 1 / S and outputs it as a comparison frequency d, a comparison frequency b output from the frequency divider 102, and a comparison frequency output from the frequency divider 208 d, a phase comparator 103 that outputs a phase signal corresponding to the phase difference between the two, a charge pump 104 that outputs a voltage based on the phase signal output from the phase comparator 103, and a charge pump 104 And a low-pass filter 205 that transmits the voltage output from the oscillating frequency c based on a transfer function controlled by an externally input control signal, and divides the oscillation frequency c output from the voltage controlled oscillator 106 by 1 / K. A frequency divider 109 that outputs an IF frequency e, an oscillation frequency c output from the voltage controlled oscillator 106, and an IF frequency e output from the frequency divider 109 are synthesized. And a mixer 110 that outputs a transmission carrier frequency f that is a transmission carrier frequency signal TX-Lo. The oscillation frequency c output from the voltage controlled oscillator 106 is controlled based on the voltage transmitted from the low-pass filter 205. Then, the oscillation frequency c is output as the receiving station frequency signal RX-Lo.

[0004] In the frequency generating circuit configured as described above, the receiving station-originated frequency signal RX-Lo and the transmission carrier frequency signal TX-Lo are generated in a time-division manner.

[0005] Assuming that the reference frequency a output from the reference oscillator 101 is a fixed value, the oscillation of the voltage-controlled oscillator 106 which becomes the frequency of the reception station-originated frequency signal Rx-Lo. The frequency c is
By controlling the comparison frequency b and the comparison frequency d to have the same frequency and the same phase, c = b × S = (a
/ R) × S.

Therefore, the receiving station frequency signal Rx-L
“o” can be set to an arbitrary frequency by designating the frequency division number R in the frequency divider 102 and the frequency division number S in the frequency divider 208.

In the transmission carrier frequency signal TX-Lo, the transmission carrier frequency f of the mixer 110, which is the frequency of the transmission carrier frequency signal TX-Lo, is f = c + e.
= C + (c / K) = c × ((K + 1) / K) = (a /
R) × S × ((K + 1) / K).

Accordingly, the transmission carrier frequency signal TX-
Lo is the division number R in the frequency divider 102 and the frequency divider 208
The frequency can be set to any frequency by designating the frequency division number S in the above and the frequency division number K in the frequency divider 109.

Here, the frequency generating circuit configured as described above operates as a PLL circuit, but in order to obtain stable operation as a PLL circuit, the transfer characteristics of the entire PLL circuit must be adjusted when generating a frequency signal from a receiving station. And when the transmission carrier frequency signal is generated. The transfer characteristics of the entire PLL circuit include the oscillation frequency c output from the voltage controlled oscillator 106, the voltage sensitivity of the voltage controlled oscillator 106, the frequency division number S of the frequency divider 208, and the comparison output from the frequency divider 102. It is determined by the frequency b, the current I of the charge pump 104, and the transfer function of the low-pass filter 205.

However, the oscillation frequency c output from the voltage controlled oscillator 106 cannot be arbitrarily selected because the purpose is to obtain a predetermined frequency. It is technically difficult to switch between when a local oscillation frequency signal is generated and when a transmission carrier frequency signal is generated. Further, since the oscillation frequency c output from the voltage controlled oscillator 106 cannot be selected, when the comparison frequency b output from the frequency divider 102 is determined, the frequency division number S of the frequency divider 208 is determined accordingly.

Therefore, in order to operate the PLL circuit stably, the comparison frequency b output from the frequency divider 102
And the current I of the charge pump 104 and the low-pass filter 2
It is necessary to switch any one of the transfer functions of the transfer function of FIG. 5 between the time of generation of the receiving station frequency signal and the time of generation of the transmission carrier frequency signal. In the low-pass filter 205, the circuit constants such as the resistance and the capacitor are switched by a switch. Since the transfer function can be switched, conventionally, the transfer characteristic of the PLL circuit is switched between when the receiving station-originated frequency signal is generated and when the transmission carrier frequency signal is generated by switching the transfer function of the low-pass filter 205.

In the portable telephone, the oscillation frequency c output from the voltage controlled oscillator 106 and the mixer 110
As shown in FIG. 4, the oscillation frequency c output from the voltage-controlled oscillator 106 is divided by the frequency divider 109 into 1 / K as shown in FIG. After that, in the mixer 110, the oscillation frequency c output from the voltage controlled oscillator 106 and the frequency divider 10
The frequency conversion is performed by synthesizing the frequency divided by 9 with the frequency.

In this case, assuming that the frequency interval per channel is dF, the receiving station frequency signal RX-Lo is expressed as dF.
Since the frequency must be set at the F interval, the oscillation frequency c output from the voltage controlled oscillator 106 must be set at the dF interval.

In order to set the transmission carrier frequency signal TX-Lo at dF intervals, the oscillation frequency c output from the voltage controlled oscillator 106 is set to dF / (K / (K + 1)).
Must be set at intervals.

Therefore, in the conventional example shown in FIG.
The comparison frequency b output from the frequency divider 102 is determined by dF when a receiving station-originated frequency signal is generated.
When a transmission carrier frequency signal is generated, dF / (K / (K +
1)).

Further, it is known that a higher comparison frequency b output from the frequency divider 102 is advantageous for shortening the lock time of the PLL. The comparison frequency b output from
There is a method of setting F or a multiple of dF / (K / (K + 1)).

FIG. 5 is a block diagram showing another example of a conventional frequency generating circuit.

In this conventional example, as shown in FIG. 5, the frequency division ratio of N / M is determined by dividing the oscillation frequency c output from the voltage controlled oscillator 106 with respect to that shown in FIG. The only difference is that the fractional frequency divider 108 is provided instead of the frequency divider 208.

[0019]

In the conventional frequency generating circuit as described above, the transfer characteristic of the PLL circuit is switched between when the receiving station oscillating frequency signal is generated and when the transmitting carrier frequency signal is generated. Although the transfer function is switched, when the transfer function of the low-pass filter is switched, circuit constants such as resistors and capacitors are switched by switches, so the number of components increases,
There is a problem that the cost is increased.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and has as its object to provide a frequency generating circuit capable of reducing the number of components and cost. I do.

[0021]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a reference oscillator for outputting a reference frequency, a frequency divider for dividing a reference frequency output from the reference oscillator, and an output as a first comparison frequency. A first frequency divider, a voltage controlled oscillator that outputs an oscillation frequency, a frequency divider that divides the oscillation frequency output from the voltage controlled oscillator and outputs the frequency as a second comparison frequency, A first comparison frequency output from the first frequency divider and a second comparison frequency output from the fractional frequency divider, and outputs a phase signal corresponding to a phase difference between the two. A charge pump for outputting a voltage based on the phase signal output from the phase comparator; a low-pass filter for transmitting the voltage output from the charge pump based on a predetermined transfer function; A second frequency divider for dividing and outputting the oscillation frequency output from the voltage divider, and an oscillation frequency output from the voltage controlled oscillator and an oscillation frequency divided by the second frequency divider. Combining means for combining and outputting as a transmission carrier frequency signal, wherein the oscillation frequency output from the voltage controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output from the receiving station. In the frequency generating circuit output as a frequency signal, when the receiving station-originated frequency signal is generated, if the reference frequency is a and the channel interval is dF, the frequency dividing number R in the first frequency divider is R = A / (dF × X) (X is a natural number), the denominator of the frequency division number in the fractional frequency divider is X, and when the transmission carrier frequency signal is generated,
Assuming that the division number in the second divider is K, the division number R in the first divider is R = a (K + 1) /
(DF × K × X), the denominator of the frequency division number in the fractional frequency divider is X, and the current of the charge pump when the receiving station frequency signal is generated is I. The current of the charge pump is represented by I × (K +
1) / K

Thus, the first comparison frequency is controlled so as to be X times the channel interval dF when a receiving station-originated frequency signal is generated, and the first comparison frequency is generated when a transmission carrier frequency signal is generated. If the frequency is dF × X × (K
+1) / K and the current of the charge pump is (K + 1) K at the time of generation of the frequency signal from the receiving station.
Since the control is performed so as to double the frequency, the stable operation of the PLL circuit can be obtained without changing the transfer function of the low-pass filter.

Also, a reference oscillator for outputting a reference frequency, a first frequency divider for dividing the reference frequency output from the reference oscillator and outputting it as a first comparison frequency, and a voltage for outputting an oscillation frequency A control oscillator, a fractional frequency divider that divides an oscillation frequency output from the voltage-controlled oscillator and outputs the frequency as a second comparison frequency, and a first comparison frequency output from the first frequency divider. A phase comparator that compares a phase with a second comparison frequency output from the fractional frequency divider and outputs a phase signal corresponding to a phase difference between the two, and based on the phase signal output from the phase comparator A charge pump for outputting a voltage, a low-pass filter for transmitting the voltage output from the charge pump based on a predetermined transfer function, and a frequency-divided oscillation frequency output from the voltage-controlled oscillator for output. A second frequency divider; and subtraction means for subtracting the oscillation frequency divided by the second frequency divider from the oscillation frequency output from the voltage controlled oscillator and outputting the result as a transmission carrier frequency signal. An oscillation frequency output from the voltage controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output as a reception station oscillation frequency signal. When a frequency signal is generated, if the reference frequency is a and the channel interval is dF, the first
R = a / (dF × X)
(X is a natural number), the denominator of the frequency divider in the fractional frequency divider is X, and the frequency divider in the second frequency divider is K when the transmission carrier frequency signal is generated. The division number R in the first frequency divider is represented by R = a (K
-1) / (dF × K × X), the denominator of the frequency division number in the fractional frequency divider is X, and the current of the charge pump at the time of generation of the receiving station frequency signal is I. In this case, the current of the charge pump is
× (K-1) / K.

Thus, the first comparison frequency is controlled so as to be X times the channel interval dF when the receiving station frequency signal is generated, and the first comparison frequency is generated when the transmission carrier frequency signal is generated. If the frequency is dF × X × (K
-1) / K and the current of the charge pump is (K-1) K at the time of generating the receiving station frequency signal.
Since the control is performed so as to double the frequency, the stable operation of the PLL circuit can be obtained without changing the transfer function of the low-pass filter.

Also, a reference oscillator for outputting a reference frequency, a first frequency divider for dividing the reference frequency output from the reference oscillator and outputting it as a first comparison frequency, and a voltage for outputting an oscillation frequency A control oscillator, a fractional frequency divider that divides an oscillation frequency output from the voltage-controlled oscillator and outputs the frequency as a second comparison frequency, and a first comparison frequency output from the first frequency divider. A phase comparator that compares a phase with a second comparison frequency output from the fractional frequency divider and outputs a phase signal corresponding to a phase difference between the two, and based on the phase signal output from the phase comparator A charge pump for outputting a voltage, a low-pass filter for transmitting the voltage output from the charge pump based on a predetermined transfer function, and a frequency-divided oscillation frequency output from the voltage-controlled oscillator for output. A second frequency divider, and combining means for combining the oscillation frequency output from the voltage-controlled oscillator with the oscillation frequency divided by the second frequency divider and outputting the resultant as a transmission carrier frequency signal. An oscillation frequency output from the voltage-controlled oscillator is controlled based on a voltage transmitted from the low-pass filter, and the oscillation frequency is output as a reception station oscillation frequency signal. When the oscillation frequency signal is generated, if the reference frequency is a and the channel interval is dF, the first
R = a / (dF × X)
(X is a natural number), the denominator of the frequency divider in the fractional frequency divider is X, and the frequency divider in the second frequency divider is K when the transmission carrier frequency signal is generated. The frequency division number R in the first frequency divider is represented by R = a /
(DF × X), and the denominator of the frequency division number in the fractional frequency divider is X × (K + 1) / K.

Thus, the first comparison frequency is controlled so as to be X times the channel interval dF when a receiving station-originated frequency signal is generated, and the second comparison frequency is generated when a transmission carrier frequency signal is generated. Since the frequency is controlled by the denominator of the fractional frequency divider being X × (K + 1) / K, without changing the transfer function of the low-pass filter,
A stable operation of the PLL circuit is obtained.

Also, a reference oscillator for outputting a reference frequency, a first frequency divider for dividing the reference frequency output from the reference oscillator and outputting it as a first comparison frequency, and a voltage for outputting an oscillation frequency A control oscillator, a fractional frequency divider that divides an oscillation frequency output from the voltage-controlled oscillator and outputs the frequency as a second comparison frequency, and a first comparison frequency output from the first frequency divider. A phase comparator that compares a phase with a second comparison frequency output from the fractional frequency divider and outputs a phase signal corresponding to a phase difference between the two, and based on the phase signal output from the phase comparator A charge pump for outputting a voltage, a low-pass filter for transmitting the voltage output from the charge pump based on a predetermined transfer function, and a frequency-divided oscillation frequency output from the voltage-controlled oscillator for output. A second frequency divider; and subtraction means for subtracting the oscillation frequency divided by the second frequency divider from the oscillation frequency output from the voltage controlled oscillator and outputting the result as a transmission carrier frequency signal. An oscillation frequency output from the voltage controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output as a reception station oscillation frequency signal. When a frequency signal is generated, if the reference frequency is a and the channel interval is dF, the first
R = a / (dF × X)
(X is a natural number), the denominator of the frequency divider in the fractional frequency divider is X, and the frequency divider in the second frequency divider is K when the transmission carrier frequency signal is generated. The frequency division number R in the first frequency divider is represented by R = a /
(DF × X), and the denominator of the frequency division number in the fractional frequency divider is X × (K−1) / K.

Thus, the first comparison frequency is controlled so as to be X times the channel interval dF when a receiving station frequency signal is generated, and the second comparison frequency is generated when a transmission carrier frequency signal is generated. Since the frequency is controlled by setting the denominator of the fractional frequency divider to X × (K−1) / K, without changing the transfer function of the low-pass filter,
A stable operation of the PLL circuit is obtained.

Also, a reference oscillator for outputting a reference frequency, a first frequency divider for dividing the reference frequency output from the reference oscillator and outputting it as a first comparison frequency, and a voltage for outputting an oscillation frequency A control oscillator, a fractional frequency divider that divides an oscillation frequency output from the voltage-controlled oscillator and outputs the frequency as a second comparison frequency, and a first comparison frequency output from the first frequency divider. A phase comparator that compares a phase with a second comparison frequency output from the fractional frequency divider and outputs a phase signal according to a phase difference between the two, and a charge pump that outputs a voltage based on the phase signal. A low-pass filter that transmits the voltage output from the charge pump based on a predetermined transfer function, and a second frequency divider that divides and outputs an oscillation frequency output from the voltage-controlled oscillator.
A frequency divider that combines the oscillation frequency output from the voltage-controlled oscillator and the oscillation frequency divided by the second frequency divider, and outputs the synthesized signal as a transmission carrier frequency signal in a first band. 1, a third frequency divider for dividing and outputting the oscillation frequency output from the voltage controlled oscillator, and an oscillation frequency output from the voltage controlled oscillator and the third frequency divider. Second combining means for combining the divided oscillation frequency with the divided oscillation frequency and outputting the combined signal as a transmission carrier frequency signal in a second band, wherein the voltage-controlled oscillator is provided based on a voltage transmitted from the low-pass filter. A frequency generating circuit that controls an oscillation frequency output from the receiving station and outputs the oscillation frequency as a receiving station emitting frequency signal in the first and second bands. At the time of occurrence, when the reference frequency is a and the channel interval is dF, the frequency division number R in the first frequency divider is R = a / (dF × X) (X is a natural number), When the denominator of the frequency division number in the fractional frequency divider is X, and when the transmission carrier frequency signal in the first band is generated, the frequency division number in the second frequency divider is K, The frequency dividing number R in the frequency divider is represented by R = a /
(DF × X), the denominator of the frequency division number in the fractional frequency divider is X × (K + 1) / K, and when the receiving station frequency signal is generated in the second band, the reference frequency is a, when the channel interval is dF, the dividing number R in the first frequency divider is R = a / (dF × X), and the denominator of the dividing number in the fractional frequency divider is X
When a transmission carrier frequency signal is generated in the second band, when the frequency division number in the third frequency divider is L, the frequency division number R in the first frequency divider is represented by R = a /
(DF × X), and the denominator of the frequency division number in the fraction frequency divider is X × (L + 1) / L.

Thus, when the frequency signal from the receiving station is generated, the first comparison frequency is controlled to be X times the channel interval dF, and when the transmission carrier frequency signal is generated, the second comparison frequency is controlled. Since the frequency is controlled by the denominator of the fractional frequency divider being X × (K + 1) / K, without changing the transfer function of the low-pass filter,
A stable operation of the PLL circuit is obtained.

Further, a reference oscillator for outputting a reference frequency, a first frequency divider for dividing the reference frequency output from the reference oscillator and outputting it as a first comparison frequency, A first voltage controlled oscillator for outputting, a second voltage controlled oscillator for outputting a second oscillation frequency, a first oscillation frequency output from the first voltage controlled oscillator, and the second voltage controlled oscillator A first switching means for selecting and outputting one of the second oscillation frequency output from the first and the second oscillation frequency, and dividing the oscillation frequency output from the first switching means into a second comparison frequency. The output fractional frequency divider compares the phase of the first comparison frequency output from the first frequency divider with the phase of the second comparison frequency output from the fractional frequency divider. A phase comparator that outputs a phase signal corresponding to A charge pump that outputs a voltage based on the phase signal, first and second low-pass filters that respectively transfer voltages output from the charge pump based on a predetermined transfer function, and a voltage output from the charge pump. Switching means for outputting the first oscillation frequency to one of the first and second low-pass filters, and a second means for dividing and outputting the first oscillation frequency output from the first voltage controlled oscillator. A frequency divider synthesizes a first oscillation frequency output from the first voltage controlled oscillator with a first oscillation frequency divided by the second frequency divider, and synthesizes the first oscillation frequency in a first band. First synthesizing means for outputting as a transmission carrier frequency signal, a third frequency divider for dividing and outputting a second oscillation frequency output from the second voltage controlled oscillator, and a second voltage From controlled oscillator Second synthesizing means for synthesizing the input second oscillation frequency and the second oscillation frequency divided by the third frequency divider, and outputting as a transmission carrier frequency signal in a second band; And a first oscillation frequency output from the first voltage-controlled oscillator is controlled based on a voltage transmitted from the first low-pass filter, and the first oscillation frequency is adjusted to a first band. Is output as a frequency signal generated by the receiving station at
A second oscillation frequency output from the second voltage-controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the second oscillation frequency is used as a reception local oscillation frequency signal in a second band. In the output frequency generating circuit, when a receiving station-generated frequency signal in the first band is generated, the first voltage controlled oscillator is selected by the first switching means, and the second switching means selects the first voltage controlled oscillator. When the first low-pass filter is selected, the reference frequency is a, and the channel interval is dF, the frequency division number R in the first frequency divider is R = a / (dF ×
X) (X is a natural number), and the denominator of the frequency division number in the fractional frequency divider is X. When a transmission carrier frequency signal in the first band is generated, the first switching means controls the first frequency. When the voltage-controlled oscillator is selected and the first low-pass filter is selected by the second switching means, and the frequency division number in the second frequency divider is K, the first frequency division is performed. The dividing number R in the vessel is
R = a / (dF × X), the denominator of the frequency division number in the fractional frequency divider is X × (K + 1) / K, and when a receiving station frequency signal is generated in the second band, A case where the second voltage controlled oscillator is selected by the first switching means, the second low-pass filter is selected by the second switching means, and the reference frequency is a and the channel interval is dF. , The dividing number R in the first frequency divider is R = a / (dF × X), and the denominator of the dividing number in the fractional frequency divider is X,
When a transmission carrier frequency signal is generated in the second band, the first switching means selects the second voltage-controlled oscillator, and the second switching means selects the second low-pass filter. When the frequency divider in the third frequency divider is L, the frequency divider R in the first frequency divider is R = a / (dF × X), and the frequency divider is Is the denominator of the divisor in X ×
(L + 1) / L.

Thus, the first comparison frequency is controlled so as to be X times the channel interval dF when a receiving station frequency signal is generated, and the second comparison frequency is generated when a transmission carrier frequency signal is generated. Since the frequency is controlled by the denominator of the fractional frequency divider being X × (K + 1) / K, without changing the transfer function of the low-pass filter,
A stable operation of the PLL circuit is obtained.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a first embodiment of a frequency generating circuit according to the present invention.

In this embodiment, as shown in FIG.
, And a reference frequency a output from the reference oscillator 1 is divided by 1 / R to obtain a first comparison frequency b.
, A voltage-controlled oscillator 6 that outputs an oscillation frequency c, and a frequency-divided oscillation frequency c output from the voltage-controlled oscillator 6 into N / M. And a comparison between the phase of the comparison frequency b output from the frequency divider 2 and the phase of the comparison frequency d output from the fractional frequency divider 8, and a phase signal corresponding to the phase difference between the two. And a charge pump 4 for outputting a voltage based on the phase signal output from the phase comparator 3
A low-pass filter 5 for transmitting the voltage output from the charge pump 4 based on a predetermined transfer function, and an oscillation frequency c output from the voltage controlled oscillator 6 divided by 1 / K, and output as an IF frequency e A second frequency divider 9, an oscillation frequency c output from the voltage controlled oscillator 6, and a frequency divider 9
And a mixer 10 which synthesizes the IF frequency e output from the mixer and outputs a transmission carrier frequency f which becomes a transmission carrier frequency signal TX-Lo. The oscillation frequency c output from the voltage controlled oscillator 6 is controlled based on
This oscillation frequency c is output as the receiving station oscillation frequency signal RX-Lo.

The operation of the frequency generator configured as described above will be described below.

When the reference frequency a is output from the reference oscillator 1, the reference frequency a is divided by the frequency divider 2 into 1 / R.
It is output as the comparison frequency b. Here, the comparison frequency b
Is represented by b = a / R.

Further, the oscillation frequency c
Is output, the oscillation frequency c is divided by the fractional frequency divider 8 into N /
The frequency is divided by M and output as the comparison frequency d. Here, the comparison frequency d is represented by d = c · N / M.

The comparison frequency b output from the frequency divider 2 and the comparison frequency d output from the fractional frequency divider 8 are input to the phase comparator 3 and output from the frequency divider 2 in the phase comparator 3. The phase of the comparison frequency b and the comparison frequency d output from the fractional frequency divider 8 are compared, and a phase signal corresponding to the phase difference between the two is output.

The phase signal output from the phase comparator 3 is input to the charge pump 4, and the charge pump 4 outputs a voltage based on the phase signal output from the phase comparator 3.

The voltage output from the charge pump 4 is
The signal is transmitted by the low-pass filter 5 based on a predetermined transfer function and applied to the voltage-controlled oscillator 6.

In the voltage controlled oscillator 6, the output oscillation frequency c is controlled based on the voltage applied from the low-pass filter 5, and this oscillation frequency c is output as the reception local oscillation frequency signal RX-Lo.

The oscillation frequency c output from the voltage controlled oscillator 6 is divided by the frequency divider 9 into 1 / K, and is output as the IF frequency e. Here, IF frequency e is e
= C / K.

The IF frequency e output from the frequency divider 9 is input to the mixer 10, where the IF frequency e output from the frequency divider 9 and the oscillation frequency c output from the voltage controlled oscillator 6 are mixed. The signal is synthesized and output as a transmission carrier frequency f which becomes a transmission carrier frequency signal TX-Lo. Here, the transmission carrier frequency f is represented by f = c + e.

In the above-mentioned frequency generating circuit, the receiving station-originated frequency signal RX-Lo and the transmission carrier frequency signal TX-Lo are generated in a time-division manner.

Assuming that the reference frequency a output from the reference oscillator 1 is a fixed value, the oscillation of the voltage controlled oscillator 6 having the frequency of the reception local oscillation frequency signal Rx-Lo is obtained. The frequency c is controlled such that the comparison frequency b and the comparison frequency d have the same frequency and the same phase, so that c = b × M / N = (a /
R) × (M / N).

Therefore, the receiving station frequency signal Rx-L
“o” can be set to an arbitrary frequency by designating the denominator N and the numerator M of the frequency dividing number R in the frequency divider 2 and the frequency dividing number M / N in the frequency divider 8.

In the transmission carrier frequency signal TX-Lo, the transmission carrier frequency f of the mixer 10 which is the frequency of the transmission carrier frequency signal TX-Lo is f = c + e =
c + (c / K) = c × ((K + 1) / K) = (a / R)
× (M / N) × ((K + 1) / K).

Therefore, the transmission carrier frequency signal TX-
Lo can be arbitrarily determined by designating the frequency dividing number R in the frequency divider 2, the denominator N and the numerator M of the frequency dividing number M / N in the frequency divider 8, and the frequency dividing number K in the frequency divider 9. Can be frequency.

Here, the above-described frequency generating circuit operates as a PLL circuit. To obtain a stable operation as a PLL circuit, the transmission characteristics of the entire PLL circuit are determined when the frequency signal from the receiving station is generated and when the transmitting carrier wave is generated. It is necessary to switch between when a frequency signal is generated. The transfer characteristics of the entire PLL circuit include an oscillation frequency c output from the voltage controlled oscillator 6 and
Voltage sensitivity of voltage controlled oscillator 6, frequency division number M / N of fractional frequency divider 8, comparison frequency b output from frequency divider 2, current I of charge pump 4, transfer function of low pass filter 5, Is determined by

However, the oscillation frequency c output from the voltage-controlled oscillator 6 cannot be arbitrarily selected because the purpose is to obtain a predetermined frequency. It is technically difficult to switch between when a local oscillation frequency signal is generated and when a transmission carrier frequency signal is generated (50 MHz / V constant in this embodiment). In addition, since the oscillation frequency c output from the voltage controlled oscillator 6 cannot be selected, when the comparison frequency b output from the frequency divider 2 is determined, the frequency division number M of the fractional frequency divider 8 is accordingly determined.
/ N is decided.

Therefore, in order to stably operate the PLL circuit, any one of the comparison frequency b output from the frequency divider 2, the current I of the charge pump 4, and the transfer function of the low-pass filter 5 is transmitted from the receiving station. It is necessary to switch between when a frequency signal is generated and when a transmission carrier frequency signal is generated.

Also, in the portable telephone, a problem occurs in which the oscillation frequency c output from the voltage controlled oscillator 6 and the transmission carrier frequency f output from the mixer 10 become the same, and as shown in FIG. The oscillating frequency c output from the voltage controlled oscillator 6 is divided by the frequency divider 9 into 1 / K, and thereafter, the oscillating frequency c output from the voltage controlled oscillator 6 and the divided frequency Frequency conversion is performed by synthesizing the divided frequency.

In this case, assuming that the frequency interval per channel is dF, the receiving station frequency signal RX-Lo is dF.
Since the oscillation frequency c must be set at F intervals, the oscillation frequency c output from the voltage controlled oscillator 6 must be set at dF intervals.

Further, in order to set the transmission carrier frequency signal TX-Lo at dF intervals, it is necessary to set the oscillation frequency c output from the voltage controlled oscillator 6 at dF / (K / (K + 1)) intervals. is there.

Therefore, in the frequency generating circuit shown in FIG. 1, the comparison frequency b output from the frequency divider 2 is determined by dF when the receiving station-originated frequency signal is generated, and when the transmission carrier frequency signal is generated. Is dF / (K / (K
+1)).

Further, it is known that a higher comparison frequency b output from the frequency divider 2 is advantageous for shortening the lock time of the PLL. Is set to dF or a multiple of dF / (K / (K + 1)).

In this embodiment, the transfer function of the low-pass filter 5 is fixed, the reference frequency a output from the reference oscillator 1 is 14.4 MHz, and the frequency division number in the frequency divider 9 is K = 4. .

Therefore, in this embodiment, since the frequency interval dF per channel is dF = 25 kHz, the oscillation frequency c output from the voltage controlled oscillator 6 is calculated as dF / (K / (K + 1)) = 25 /
It is necessary to set at (4/5) = 20 kHz intervals.

When a frequency signal generated by the receiving station is generated, the dividing frequency R in the frequency divider 2 is set to R = 36, so that the comparison frequency b output from the frequency divider 2 is b = a / R
= 14.4 MHz / 36 = 400 kHz, whereby the comparison frequency b output from the frequency divider 2 is set to 16 times the frequency interval dF per channel. Also, the current of the charge pump 4 is I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is N = 16 which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel. And

When the transmission carrier frequency signal is generated, the frequency division number R in the frequency divider 2 is set to R = 45, so that the comparison frequency b output from the frequency divider 2 is b = a / R
= 14.4 MHz / 45 = 320 kHz, whereby the comparison frequency b output from the frequency divider 2 is set to the frequency interval dF per channel (the frequency interval dF per channel at the time of generating the frequency signal from the receiving station). × (K / (K + 1)) = (1
6 × 4/5) times. Further, the current of the charge pump 4 is set to I × ((K + 1) / K) = 1 mA × 5/4 = 1.2
5 mA, and the frequency division number M / N in the fractional frequency divider 8
Is N = 16 which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel at the time of generation of the receiving station-originated frequency signal.

(Second Embodiment) In this embodiment,
The mixer 10 shown in FIG. 1 serves as a subtraction unit, and subtracts the IF frequency e output from the frequency divider 9 from the oscillation frequency c output from the voltage controlled oscillator 6 and outputs the result. here,
The transmission carrier frequency f output from the mixer 10 is f =
= Ce.

Assuming that the reference frequency a output from the reference oscillator 1 is a fixed value, the oscillation of the voltage controlled oscillator 6 having the frequency of the reception local oscillation frequency signal Rx-Lo is obtained. The frequency c is controlled such that the comparison frequency b and the comparison frequency d have the same frequency and the same phase, so that c = b × M / N = (a /
R) × (M / N).

Accordingly, the receiving station frequency signal Rx-L
“o” can be set to an arbitrary frequency by designating the frequency dividing ratio R in the frequency divider 2 and the denominator N and the numerator M of the frequency dividing number M / N in the fractional frequency divider 8.

In the transmission carrier frequency signal TX-Lo, the transmission carrier frequency f of the mixer 10, which is the frequency of the transmission carrier frequency signal TX-Lo, is given by f = ce =
c− (c / K) = c × ((K−1) / K) = (a / R)
× (M / N) × ((K−1) / K).

Therefore, the transmission carrier frequency signal TX-
Lo is an arbitrary value by designating the frequency dividing ratio R in the frequency divider 2, the denominator N and the numerator M of the frequency dividing number M / N in the fractional frequency divider 8, and the frequency dividing number K in the frequency divider 9. Can be frequency.

Also, in this embodiment, if the frequency interval per channel is dF, the receiving station-originated frequency signal RX-Lo must be set at the dF interval.
It is necessary to set the oscillation frequency c output from the voltage controlled oscillator 6 at dF intervals.

In order to set the transmission carrier frequency signal TX-Lo at dF intervals, the oscillation frequency c output from the voltage controlled oscillator 6 is set at dF / (K / (K-1)) intervals. There is a need.

In the present embodiment, the transfer function of the low-pass filter 5 is fixed, the reference frequency a output from the reference oscillator 1 is 14.4 MHz, and the frequency division number in the frequency divider 9 is K = 4. .

Therefore, in this embodiment, since the frequency interval dF per channel is dF = 25 kHz, K = 4 and the oscillation frequency c output from the voltage controlled oscillator 6 becomes dF / (K / (K-1)) = 25 /
It is necessary to set at (4/3) = 33.33 kHz interval.

When a frequency signal generated by the receiving station is generated, the frequency division number R in the frequency divider 2 is set to R = 36, so that the comparison frequency b output from the frequency divider 2 is b = a / R
= 14.4 MHz / 36 = 400 kHz, whereby the comparison frequency b output from the frequency divider 2 is set to 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is equal to N which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel.
= 16.

When the transmission carrier frequency signal is generated, by setting the frequency dividing number R in the frequency divider 2 to R = 27, the comparison frequency b output from the frequency divider 2 is b = a / R
= 14.4 MHz / 27 = 533.33 kHz, whereby the comparison frequency b output from the frequency divider 2 is set at the frequency interval dF per channel (the frequency per channel at the time of generation of the frequency signal from the receiving station). Interval d
F: magnification of comparison frequency b with respect to F) × (K / (K−1))
= (16 × 4/3) times. In addition, charge pump 4
Is given by I × ((K−1) / K) = 1 mA × 3/4 =
Further, the denominator N of the frequency division number M / N in the fractional frequency divider 8 is set to 0.75 mA, and N = 16 which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel at the time of generation of the frequency signal from the receiving station. And

(Third Embodiment) This embodiment is similar to the first embodiment in that the receiving station frequency signal RX
-Lo, if the reference frequency a output from the reference oscillator 1 is a fixed value, the reception local oscillation frequency signal R
The oscillation frequency c of the voltage controlled oscillator 6 having the frequency of x-Lo is controlled such that the comparison frequency b and the comparison frequency d have the same frequency and the same phase, so that c = b × M
/ N = (a / R) × (M / N).

Therefore, the receiving station frequency signal Rx-L
“o” can be set to an arbitrary frequency by designating the denominator N and the numerator M of the frequency dividing number R in the frequency divider 2 and the frequency dividing number M / N in the frequency divider 8.

In the transmission carrier frequency signal TX-Lo, the transmission carrier frequency f of the mixer 10 which is the frequency of the transmission carrier frequency signal TX-Lo is f = c + e =
c + (c / K) = c × ((K + 1) / K) = (a / R)
× (M / N) × ((K + 1) / K).

Therefore, the transmission carrier frequency signal TX-
Lo can be arbitrarily specified by designating the frequency division number R in the frequency divider 2, the denominator N and the numerator M of the frequency division ratio M / N in the frequency divider 8, and the frequency division number K in the frequency divider 9. Can be frequency.

Also in this embodiment, if the frequency interval per channel is dF, the receiving station-originated frequency signal RX-Lo must be set at the dF interval.
It is necessary to set the oscillation frequency c output from the voltage controlled oscillator 6 at dF intervals.

In order to set the transmission carrier frequency signal TX-Lo at dF intervals, it is necessary to set the oscillation frequency c output from the voltage controlled oscillator 6 at dF / (K / (K + 1)) intervals. is there.

In this embodiment, the transfer function of the low-pass filter 5 is fixed, the reference frequency a output from the reference oscillator 1 is 14.4 MHz, and the frequency division number in the frequency divider 9 is K = 4. .

Thus, in the present embodiment, since the frequency interval dF per channel is dF = 25 kHz, K = 4 and the oscillation frequency c output from the voltage controlled oscillator 6 becomes dF / (K / (K + 1)) = 25 /
It is necessary to set at (4/5) = 20 kHz intervals.

When a frequency signal generated by the receiving station is generated, the dividing frequency R in the frequency divider 2 is set to R = 36, so that the comparison frequency b output from the frequency divider 2 is b = a / R
= 14.4 MHz / 36 = 400 kHz, whereby the comparison frequency b output from the frequency divider 2 is set to 16 times the frequency interval dF per channel. Also, the current of the charge pump 4 is I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is N = 16 which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel. And

When the transmission carrier frequency signal is generated, the frequency division number R in the frequency divider 2 is set to R = 36, so that the comparison frequency b output from the frequency divider 2 is b = a / R
= 14.4 MHz / 36 = 400 kHz, whereby the comparison frequency b output from the frequency divider 2 is set to 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is set to I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is set to the frequency interval d per channel when the receiving station oscillated frequency signal is generated.
16 × 5/4 = 20 which is ((K + 1) / K) times the magnification of the comparison frequency b with respect to F.

In the present embodiment, since the current switching of the charge pump 4 is not required, a D / A converter circuit for switching the current of the charge pump 4 is not required, and compared with the one shown in the first embodiment. Thus, the cost can be further reduced.

(Fourth Embodiment) In this embodiment,
The mixer 10 is different from that shown in the third embodiment.
Is a subtraction means, and an IF frequency e output from the frequency divider 9 is derived from the oscillation frequency c output from the voltage controlled oscillator 6.
Is subtracted and output.

In the present embodiment, when the transmission carrier frequency signal is generated, the frequency division number R in the frequency divider 2 is set to R = 36.
As a result, the comparison frequency b output from the frequency divider 2 is set to b = a / R = 14.4 MHz / 36 = 400 kHz, whereby the comparison frequency b output from the frequency divider 2
Is 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is set to I = 1 mA,
Further, the denominator N of the frequency division number M / N in the fraction frequency divider 8 is
The ratio of the magnification of the comparison frequency b to the frequency interval dF per channel ((K
−1) / K) times 16 × 3/4 = 12.

(Fifth Embodiment) FIG. 2 is a block diagram showing a frequency generator according to a fifth embodiment of the present invention.

In the present embodiment, as shown in FIG.
, And a reference frequency a output from the reference oscillator 1 is divided by 1 / R to obtain a first comparison frequency b.
, A voltage-controlled oscillator 6 that outputs an oscillation frequency c, and a frequency-divided oscillation frequency c output from the voltage-controlled oscillator 6 into N / M. And a comparison between the phase of the comparison frequency b output from the frequency divider 2 and the phase of the comparison frequency d output from the fractional frequency divider 8, and a phase signal corresponding to the phase difference between the two. And a charge pump 4 for outputting a voltage based on the phase signal output from the phase comparator 3
A low-pass filter 5 for transmitting the voltage output from the charge pump 4 based on a predetermined transfer function, and an oscillation frequency c output from the voltage controlled oscillator 6 divided by 1 / K, and output as an IF frequency e A second frequency divider 9, an oscillation frequency c output from the voltage controlled oscillator 6, and a frequency divider 9
A mixer 10 serving as first combining means for combining the IF frequency e output from the first unit and outputting a transmission carrier frequency f which becomes the transmission carrier frequency signal TX1-Lo, and an oscillation frequency c output from the voltage controlled oscillator 6. Is divided by 1 / L, and I
The third frequency divider 11 that outputs the F frequency g, the oscillation frequency c that is output from the voltage controlled oscillator 6 and the IF frequency g that is output from the frequency divider 11 are combined to transmit the transmission carrier frequency signal TX2-Lo. And a mixer 12 serving as a second combining means for outputting a transmission carrier frequency h. The oscillation frequency c output from the voltage-controlled oscillator 6 is controlled based on the voltage transmitted from the low-pass filter 5. The oscillation frequency c is the reception station oscillation frequency signal RX1
-Lo, RX2-Lo are output.

As described above, in the present embodiment, the first receiving station frequency signal RX1-Lo is used for the first band.
And a first transmission carrier frequency signal TX1-Lo, and for the second band, a second receiving station-originated frequency signal RX2-Lo and a second transmission carrier frequency signal TX
2-Lo is output.

The transmission carrier frequency f output from the mixer 10 is expressed as f = c + e by the oscillation frequency c output from the voltage controlled oscillator 6 and the IF frequency e output from the frequency divider 9. .

The transmission carrier frequency h output from the mixer 12 is expressed as h = c + g by the oscillation frequency c output from the voltage controlled oscillator 6 and the IF frequency g output from the frequency divider 11. .

In the present embodiment, the transfer function of the low-pass filter 5 is fixed, the reference frequency a output from the reference oscillator 1 is 14.4 MHz, and the frequency division number in the frequency divider 9 is K = 4. It is assumed that the frequency division number in the frequency divider 11 is L = 8.

Therefore, in the present embodiment, since the frequency interval dF per channel is dF = 25 kHz, when the frequency signal of the receiving station originates in the first band, the frequency divider 2 By setting R to R = 36, the comparison frequency b output from the frequency divider 2 becomes b =
a / R = 14.4 MHz / 36 = 400 kHz, whereby the comparison frequency b output from the frequency divider 2 is set to 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is set to I = 1 mA, and
The denominator N of the frequency division number M / N in the fractional frequency divider 8 is set to N = 16 which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel.

When a transmission carrier frequency signal in the first band is generated, the frequency division number R in the frequency divider 2 is set to R = 36, so that the comparison frequency b output from the frequency divider 2 becomes b. = A / R = 14.4MHz / 36 = 400k
Hz, whereby the comparison frequency b output from the frequency divider 2 is 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is set to I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is set.
Is set to 16 × 5/4 = 20, which is ((K + 1) / K) times the magnification of the comparison frequency b with respect to the frequency interval dF per channel at the time of generation of the receiving station frequency signal.

When a frequency signal from the receiving station is generated in the second band, the frequency division number R in the frequency divider 2 is set to R
= 36, the comparison frequency b output from the frequency divider 2 becomes b = a / R = 14.4 MHz / 36 = 400 kHz.
z, whereby the comparison frequency b output from the frequency divider 2 is set to 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is set to I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is set.
Is N = 16, which is equal to the magnification of the comparison frequency b with respect to the frequency interval dF per channel.

When the transmission carrier frequency signal is generated in the second band, the frequency division number R in the frequency divider 2 is set to R = 36, so that the comparison frequency b output from the frequency divider 2 becomes b. = A / R = 14.4MHz / 36 = 400k
Hz, whereby the comparison frequency b output from the frequency divider 2 is 16 times the frequency interval dF per channel. Further, the current of the charge pump 4 is set to I = 1 mA, and the denominator N of the frequency division number M / N in the fractional frequency divider 8 is set to ((L +
1) / (L) × 16 × 9/8 = 18.

In the present embodiment, when generating a frequency in the first band, the voltage sensitivity of the voltage controlled oscillator 6 is set to 50 MHz / V. When generating a frequency in the second band, the voltage sensitivity of the voltage-controlled oscillator 6 is set to 70 MHz / V from the calculation formula so that the low-pass filter 5 has the same transfer function.

Even in this case, if the voltage sensitivity of the voltage controlled oscillator 6 at the time of frequency generation in the second band cannot be set to a predetermined value, for example, if it becomes 35 MHz / V, the charge pump 4 May be set to 2 mA.

(Sixth Embodiment) FIG. 3 is a block diagram showing a frequency generator according to a sixth embodiment of the present invention.

In the present embodiment, as shown in FIG.
, And a reference frequency a output from the reference oscillator 1 is divided by 1 / R to obtain a first comparison frequency b.
And a first oscillation frequency j
, A second voltage-controlled oscillator 16 that outputs a second oscillation frequency i, an oscillation frequency i output from the voltage-controlled oscillator 16, and an output from the voltage-controlled oscillator 17 A switch 18 as first switching means for selecting one of the oscillation frequencies j and outputting it as an oscillation frequency c, and dividing the oscillation frequency c output from the switch 18 into N / M, and A fractional frequency divider 8 that outputs a comparison frequency d, a comparison frequency b output from the frequency divider 2 and a comparison frequency d that is output from the fractional frequency divider 8
Phase comparator 3, which outputs a phase signal corresponding to the phase difference between the two, a charge pump 4 which outputs a voltage based on the phase signal output from the phase comparator 3, and a charge pump 4 A first low-pass filter 15 that transmits the output voltages based on a predetermined transfer function, respectively.
And the second low-pass filter 14 and the charge pump 4
Switch 1, which is a second switching means for outputting the voltage output from the first to one of the low-pass filters 14 and 15
3, a second frequency divider 9 that divides the oscillation frequency c output from the voltage controlled oscillator 6 into 1 / K and outputs the result as an IF frequency e, and an oscillation frequency c output from the voltage controlled oscillator 6. A mixer 10 as first combining means for combining the IF frequency e output from the frequency divider 9 and outputting a transmission carrier frequency f which becomes the transmission carrier frequency signal TX1-Lo;
The oscillation frequency c output from the voltage controlled oscillator 6 is 1 / L
Third frequency divider 1 which divides the frequency and outputs it as IF frequency g
1 and a second output of a transmission carrier frequency h that becomes a transmission carrier frequency signal TX2-Lo by combining the oscillation frequency c output from the voltage controlled oscillator 6 and the IF frequency g output from the frequency divider 11. An oscillation frequency i output from the voltage controlled oscillator 16 is controlled based on a voltage transmitted from the low-pass filter 14, and the oscillation frequency i is controlled by the reception station oscillation frequency signal. The oscillation frequency j output from the voltage-controlled oscillator 17 is controlled based on the voltage output as RX2-Lo and the voltage transmitted from the low-pass filter 15, and this oscillation frequency j is used as the reception station oscillation frequency signal RX1-Lo. Is output.

In the frequency generating circuit configured as described above, the PLL circuit does not operate stably when the elements of the voltage controlled oscillator 6 and the low-pass filter 5 shown in the fifth embodiment have large variations. To avoid this, the voltage controlled oscillators 16 and 17 are switched by the switch 18,
Further, the switch 13 controls the low-pass filters 14 and 15
, So that the low-pass filters 14 and 15
Is selected as the optimum one for the voltage sensitivity of the voltage controlled oscillators 16 and 17.

In the first band, the voltage controlled oscillator 17 and the low-pass filter 15 are selected, and in the second band, the voltage controlled oscillator 16 and the low-pass filter 14 are selected.

When generating frequencies in two completely different frequency bands, it is conceivable to use the configuration as shown in the fifth and sixth embodiments.
It is also possible to carry out by combining the components shown in the first to fourth embodiments.

[0103]

Since the present invention is configured as described above, it is possible to generate frequency signals in two frequency bands having different frequency intervals without changing the transfer function of the low-pass filter in the PLL circuit. .

Thus, in a frequency generating circuit that generates frequency signals in two frequency bands having different frequency intervals, the number of components can be reduced and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a frequency generation circuit according to the present invention.

FIG. 2 is a block diagram showing a fifth embodiment of the frequency generation circuit of the present invention.

FIG. 3 is a block diagram illustrating a frequency generator according to a sixth embodiment of the present invention;

FIG. 4 is a block diagram illustrating a configuration example of a frequency generation circuit used in a conventional mobile phone.

FIG. 5 is a block diagram showing another example of a conventional frequency generation circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference oscillator 2, 9, 11 Divider 3 Phase comparator 4 Charge pump 5, 14, 15 Low-pass filter 6, 16, 17 Voltage controlled oscillator 8 Fractional divider 10, 12, Mixer 13, 18 Switch

Claims (6)

[Claims] A reference oscillator for outputting a reference frequency; and a first frequency divider for dividing a reference frequency output from the reference oscillator.
A first frequency divider for outputting as a comparison frequency, a voltage-controlled oscillator for outputting an oscillation frequency, and a fractional frequency for dividing the oscillation frequency output from the voltage-controlled oscillator and outputting as a second comparison frequency And a phase signal according to the phase difference between the first comparison frequency output from the first frequency divider and the second comparison frequency output from the fractional frequency divider. And a charge pump that outputs a voltage based on the phase signal output from the phase comparator, and a low-pass filter that transmits the voltage output from the charge pump based on a predetermined transfer function, A second frequency divider that divides and outputs an oscillation frequency output from the voltage controlled oscillator, and an oscillation frequency that is output from the voltage controlled oscillator and an oscillation that is divided by the second frequency divider. Frequency and Combining means for combining and outputting as a transmission carrier frequency signal, wherein the oscillation frequency output from the voltage controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output from the receiving station. In the frequency generating circuit output as a frequency signal, when the receiving station-originated frequency signal is generated, when the reference frequency is a and the channel interval is dF,
The division number R in the first frequency divider is represented by R = a / (dF
× X) (X is a natural number) and the denominator of the frequency division number in the fractional frequency divider is X. When the transmission carrier frequency signal is generated, the frequency division number in the second frequency divider is K and In this case, the frequency division number R in the first frequency divider is calculated as R = a (K + 1) /
(DF × K × X), the denominator of the frequency division number in the fractional frequency divider is X, and the current of the charge pump when the receiving station frequency signal is generated is I. The current of the charge pump is represented by I × (K +
1) A frequency generating circuit characterized by / K. 2. A reference oscillator for outputting a reference frequency, and a first frequency obtained by dividing a reference frequency output from the reference oscillator.
A first frequency divider for outputting as a comparison frequency, a voltage-controlled oscillator for outputting an oscillation frequency, and a fractional frequency for dividing the oscillation frequency output from the voltage-controlled oscillator and outputting as a second comparison frequency And a phase signal according to the phase difference between the first comparison frequency output from the first frequency divider and the second comparison frequency output from the fractional frequency divider. And a charge pump that outputs a voltage based on the phase signal output from the phase comparator, and a low-pass filter that transmits the voltage output from the charge pump based on a predetermined transfer function, A second frequency divider that divides and outputs an oscillation frequency output from the voltage controlled oscillator, and an oscillation frequency that is divided by the second frequency divider from the oscillation frequency output from the voltage controlled oscillator frequency Subtraction means for subtracting and outputting as a transmission carrier frequency signal, wherein the oscillation frequency output from the voltage-controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output from the receiving station. In the frequency generating circuit output as a frequency signal, when the receiving station-originated frequency signal is generated, when the reference frequency is a and the channel interval is dF,
The division number R in the first frequency divider is represented by R = a / (dF
× X) (X is a natural number) and the denominator of the frequency division number in the fractional frequency divider is X. When the transmission carrier frequency signal is generated, the frequency division number in the second frequency divider is K and In this case, the frequency dividing number R in the first frequency divider is calculated as R = a (K-1) /
(DF × K × X), the denominator of the frequency division number in the fractional frequency divider is X, and the current of the charge pump when the receiving station frequency signal is generated is I. The charge pump current is given by I × (K−
1) A frequency generating circuit characterized by / K. 3. A reference oscillator for outputting a reference frequency, and a first frequency obtained by dividing a reference frequency output from the reference oscillator.
A first frequency divider for outputting as a comparison frequency, a voltage-controlled oscillator for outputting an oscillation frequency, and a fractional frequency for dividing the oscillation frequency output from the voltage-controlled oscillator and outputting as a second comparison frequency And a phase signal according to the phase difference between the first comparison frequency output from the first frequency divider and the second comparison frequency output from the fractional frequency divider. And a charge pump that outputs a voltage based on the phase signal output from the phase comparator, and a low-pass filter that transmits the voltage output from the charge pump based on a predetermined transfer function, A second frequency divider that divides and outputs an oscillation frequency output from the voltage controlled oscillator, and an oscillation frequency that is output from the voltage controlled oscillator and an oscillation that is divided by the second frequency divider. Frequency and Combining means for combining and outputting as a transmission carrier frequency signal, wherein the oscillation frequency output from the voltage controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output from the receiving station. In the frequency generating circuit output as a frequency signal, when the receiving station-originated frequency signal is generated, when the reference frequency is a and the channel interval is dF,
The division number R in the first frequency divider is represented by R = a / (dF
× X) (X is a natural number) and the denominator of the frequency division number in the fractional frequency divider is X. When the transmission carrier frequency signal is generated, the frequency division number in the second frequency divider is K and In this case, the frequency division number R in the first frequency divider is calculated as follows: R = a / (dF ×
X), and the denominator of the frequency division number in the fraction frequency divider is X × (K + 1) / K. 4. A reference oscillator for outputting a reference frequency, and a first frequency obtained by dividing a reference frequency output from the reference oscillator.
A first frequency divider for outputting as a comparison frequency, a voltage-controlled oscillator for outputting an oscillation frequency, and a fractional frequency for dividing the oscillation frequency output from the voltage-controlled oscillator and outputting as a second comparison frequency And a phase signal according to the phase difference between the first comparison frequency output from the first frequency divider and the second comparison frequency output from the fractional frequency divider. And a charge pump that outputs a voltage based on the phase signal output from the phase comparator, and a low-pass filter that transmits the voltage output from the charge pump based on a predetermined transfer function, A second frequency divider that divides and outputs an oscillation frequency output from the voltage controlled oscillator, and an oscillation frequency that is divided by the second frequency divider from the oscillation frequency output from the voltage controlled oscillator frequency Subtraction means for subtracting and outputting as a transmission carrier frequency signal, wherein the oscillation frequency output from the voltage-controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is output from the receiving station. In the frequency generating circuit output as a frequency signal, when the receiving station-originated frequency signal is generated, when the reference frequency is a and the channel interval is dF,
The division number R in the first frequency divider is represented by R = a / (dF
× X) (X is a natural number) and the denominator of the frequency division number in the fractional frequency divider is X. When the transmission carrier frequency signal is generated, the frequency division number in the second frequency divider is K and In this case, the frequency division number R in the first frequency divider is calculated as follows: R = a / (dF ×
X), and a denominator of the frequency division number in the fractional frequency divider is X × (K−1) / K. 5. A reference oscillator for outputting a reference frequency, and a first frequency divider for dividing a reference frequency output from the reference oscillator.
A first frequency divider for outputting as a comparison frequency, a voltage-controlled oscillator for outputting an oscillation frequency, and a fractional frequency for dividing the oscillation frequency output from the voltage-controlled oscillator and outputting as a second comparison frequency And a phase signal according to the phase difference between the first comparison frequency output from the first frequency divider and the second comparison frequency output from the fractional frequency divider. , A charge pump that outputs a voltage based on the phase signal, a low-pass filter that transmits the voltage output from the charge pump based on a predetermined transfer function, and a voltage that is output from the voltage-controlled oscillator. A second frequency divider that divides the oscillation frequency and outputs the same, and combines the oscillation frequency output from the voltage controlled oscillator with the oscillation frequency divided by the second frequency divider to generate a second frequency. In one band First combining means for outputting a transmission carrier frequency signal, a third frequency divider for dividing and outputting an oscillation frequency output from the voltage controlled oscillator, and an oscillation frequency output from the voltage controlled oscillator. And the third
And synthesizes the oscillating frequency divided by the frequency divider and outputs as a transmission carrier frequency signal in the second band.
The oscillation frequency output from the voltage controlled oscillator is controlled based on the voltage transmitted from the low-pass filter, and the oscillation frequency is adjusted to the first and second oscillation frequencies.
In the frequency generating circuit output as the receiving station-originated frequency signal in the band of the following, when the receiving station-originating frequency signal is generated in the first band, when the reference frequency is a and the channel interval is dF,
The division number R in the first frequency divider is represented by R = a / (dF
× X) (X is a natural number) and the denominator of the frequency division number in the fractional frequency divider is X, and when the transmission carrier frequency signal is generated in the first band, the frequency in the second frequency divider is When the frequency is K, the frequency dividing number R in the first frequency divider is represented by R = a / (dF ×
X), and the denominator of the frequency division number in the fractional frequency divider is X × (K + 1) / K. When the receiving station-originated frequency signal is generated in the second band, the reference frequency is a, and the channel is When the interval is dF,
The division number R in the first frequency divider is represented by R = a / (dF
× X), the denominator of the frequency division number in the fractional frequency divider is X, and when the transmission carrier frequency signal is generated in the second band, the frequency division number in the third frequency divider is L. In this case, the frequency division number R in the first frequency divider is calculated as follows: R = a / (dF ×
X), and the denominator of the frequency division number in the fraction frequency divider is X × (L + 1) / L. 6. A reference oscillator for outputting a reference frequency, and dividing the reference frequency output from the reference oscillator to a first frequency.
A first frequency divider for outputting a comparison frequency, a first voltage controlled oscillator for outputting a first oscillation frequency, a second voltage controlled oscillator for outputting a second oscillation frequency,
A first switching means for selecting and outputting one of a first oscillation frequency output from the voltage-controlled oscillator and a second oscillation frequency output from the second voltage-controlled oscillator; and A fractional frequency divider for dividing the oscillation frequency output from the first switching means and outputting the divided frequency as a second comparison frequency;
The phase of the first comparison frequency output from the first frequency divider is compared with the phase of the second comparison frequency output from the fractional frequency divider, and a phase signal corresponding to the phase difference between the two is output. A phase comparator, a charge pump that outputs a voltage based on the phase signal, first and second low-pass filters that respectively transfer voltages output from the charge pump based on a predetermined transfer function, and the charge pump. Switching means for outputting the voltage output from the first or second low-pass filter to one of the first and second low-pass filters, and dividing the first oscillation frequency output from the first voltage-controlled oscillator. A second divider that outputs the signal, a first oscillation frequency that is output from the first voltage-controlled oscillator, and a first oscillation frequency that is divided by the second divider; Transmission in the first band A first combining means for outputting as a wave frequency signal, and a third frequency divider for said second oscillation frequency output from the second voltage controlled oscillator by dividing the output,
A second oscillation frequency output from the second voltage controlled oscillator is combined with a second oscillation frequency divided by the third divider to generate a transmission carrier frequency signal in a second band. A second oscillating frequency output from the first voltage-controlled oscillator based on a voltage transmitted from the first low-pass filter. Is output as a receiving station oscillation frequency signal in the first band, and based on the voltage transmitted from the second low-pass filter, the second oscillation frequency output from the second voltage controlled oscillator is A frequency generating circuit that is controlled and outputs the second oscillation frequency as a receiving station-originated frequency signal in a second band;
When the first switching means selects the first voltage-controlled oscillator, and the second switching means selects the first low-pass filter, and the reference frequency is a and the channel interval is dF. ,
The division number R in the first frequency divider is represented by R = a / (dF
× X) (X is a natural number), and the denominator of the frequency division number in the fractional frequency divider is X. When the transmission carrier frequency signal in the first band is generated, the first switching means sets the When the first low-pass filter is selected by the second switching means while the first voltage-controlled oscillator is selected, and the frequency division number in the second frequency divider is K, the first division The frequency dividing number R in the frequency divider is calculated as follows: R = a / (dF ×
X) and the denominator of the frequency division number in the fractional frequency divider is X × (K + 1) / K. When a receiving station frequency signal in the second band is generated,
When the second voltage-controlled oscillator is selected by the first switching means, and the second low-pass filter is selected by the second switching means, and the reference frequency is a and the channel interval is dF. ,
The division number R in the first frequency divider is represented by R = a / (dF
× X) and the denominator of the frequency division number in the fractional frequency divider is X, and when the transmission carrier frequency signal is generated in the second band, the second voltage controlled oscillator is generated by the first switching means. Is selected, and the second low-pass filter is selected by the second switching means. When the frequency division number in the third frequency divider is L, the frequency division in the first frequency divider is performed. The number R is represented by R = a / (dF ×
X), and the denominator of the frequency division number in the fraction frequency divider is X × (L + 1) / L.