JP2579260B2 - PLL frequency synthesizer and tuner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PLL frequency synthesizer and a tuner having the same.
Audio equipment such as mini-components and boombox, televisions, CATV
PLL for electronic tuning tuner used for video equipment such as TV, cable broadcasting, wireless receiver etc.
It relates to a frequency synthesizer.

[0002]

2. Description of the Related Art Generally, a crystal oscillator is used for an oscillation circuit for generating an oscillation signal having an accurate frequency. However, crystal oscillators are expensive and large in size. Therefore,
It is preferable that the number of required oscillating signals is small, but if a large number of oscillating signals are required, arranging the oscillating circuits by the number of the oscillating signals is limited by cost and size. Even in such a case, there are few cases where all oscillation signals are used at the same time, and in most cases, a selected small number of oscillation signals are used. For example, in the generation of a local oscillation frequency signal for a frequency mixing circuit of an electronic tuning tuner, a large number of accurate oscillation signals of several tens or more having different frequencies are required. It is one of.

Here, the PLL frequency synthesizer has 1
Since an oscillation signal having an arbitrary rational multiple of frequency can be generated in principle from the two fundamental frequency signals, it is often used for generating such a local oscillation frequency signal, and the above-described restrictions are imposed. Substitutes a large number of oscillation circuits that require a crystal oscillator. This will be described below with a specific example with reference to the drawings. Figure 4 is an electronic tuning circuit using a PLL frequency synthesizer of conventional construction, have
FIG. 3 shows a block diagram of a so-called tuner section . 1
Is a high-frequency circuit, 2 is a basic oscillation circuit, 3 is a synthesizer circuit, 4 is a low-pass filter (hereinafter abbreviated as LPF), 5
Denotes a voltage controlled oscillation circuit (hereinafter abbreviated as VCO), and 6 denotes a microcomputer circuit (hereinafter abbreviated as MPU).

The high-frequency circuit 1 includes a high-frequency amplifier circuit 1a and a frequency mixing circuit 1b.
By mixing the local oscillation frequency signal FS with a high frequency such as a wave or an FM wave, an intermediate frequency signal of a selected specific frequency is output. However, the latter half is not shown. Basic oscillation circuit 2
Is configured using a crystal oscillator to generate a fundamental frequency signal FB having an accurate period. Synthesizer circuit 3
Comprises a variable frequency dividing circuit 3a, a variable frequency dividing circuit 3b, and a phase comparing circuit 3c for comparing the phase and the period of the signal divided by these. Further, a synthesizer control circuit is provided to receive a control parameter or the like from an external MPU 6 and determine a frequency division ratio or the like in the frequency divider circuit according to the control parameter or the like.

The LPF 4 and VCO 5 are provided with a variable frequency divider 3
b, constitutes a feedback loop together with the phase comparison circuit 3c. Then, it receives the signal of the comparison result from the phase comparison circuit 3c, and outputs its own output so that the comparison result between the divided signal of the fundamental frequency signal FB and the divided signal of the local oscillation frequency signal FS becomes equal. The frequency of the local oscillation frequency signal FS, which is a signal, is increased or decreased. Although the detailed configuration is omitted in the figure, the MPU 6 normally includes a microcomputer, an interface, and the like, and sets necessary control parameters to the synthesizer circuit 3 and monitors its state.

[0006] Under such a configuration, when one tuning frequency is selected and determined in the MPU 6, the electronic tuning circuit of the above-described feedback loop, that is, a PLL (phase lock loop) receiving a parameter corresponding to the tuning frequency. By operation, a local oscillation frequency signal FS having an accurate frequency corresponding to the selection is generated from one basic frequency signal FB having an accurate frequency. In this way, VCO5
Is sent to the frequency mixing circuit 1b, where it is used to select an intermediate frequency signal.

A PLL frequency synthesizer that generates a local oscillation frequency signal FS from the fundamental frequency signal FB is frequently used in electronic tuning tuners and the like as described above, and is in great demand.
It is generally supplied in the form of an IC. The target part of this IC conversion is a basic oscillator circuit 2, a synthesizer circuit 3, an LPF
4, a PLL frequency synthesizer circuit composed of a VCO 5 and the like. However, a crystal oscillator, a capacitor with a large capacity, a driving transistor with a high speed and a large driving capacity, etc. are IC
Since it cannot be changed, it will be attached externally. In addition, in the example of FIG. 4, the frequency tuning circuit 1b, which is a part of the high frequency circuit 1, is also integrated in the same IC.
The LL frequency synthesizer IC7 is indicated by a broken line.

[0008]

By the way, in the circuit having such a configuration, since the high-frequency circuit 1 and the VCO 5 are required to have high speed and noise resistance, a relatively high power supply voltage HFVcc is required. If the power supply voltage HFVcc is low, the sensitivity and the dynamic range are reduced, the selectivity is reduced, and interference is likely to occur. For example, 9 V, 12 V, or the like is used. On the other hand, the synthesizer circuit 3 is a digital circuit, and usually has a power supply voltage SVcc of about 5 V, which is the same as the power supply voltage MPUVcc for the MPU 6, because of the matching with the external MPU 6.

For this reason, the electronic tuning PLL frequency synthesizer IC 7 is provided with two power supply terminals 7a and 7b. And an electronically tuned PLL frequency synthesizer IC
7 receives a power supply voltage HFVcc from the outside via a terminal 7a and supplies it to the VCO 5 and the frequency mixing circuit 1b,
Further, it operates by receiving a power supply voltage SVcc from the outside via the terminal 7b and supplying it to the basic oscillation circuit 2 and the synthesizer circuit 3. However, since the PLL frequency synthesizer and the high-frequency circuit cooperate closely and cooperate with each other, the propagation of the signal in the high-frequency circuit and the local oscillation frequency signal FS through long wiring is also required from the viewpoint of noise resistance and the like. Due to the difficulty, they are necessarily arranged close to each other, and in some cases, they may be partially mixed as described above.

For this reason, undesirable influences due to radiation, sneak path, and the like are likely to be exerted on each other. In particular, the influence of a harmonic component from a fundamental oscillation circuit that switches at high speed and steepness on a high-frequency circuit is large. This is a problem because it leads to an increase in the number of man-hours for tuning tuner development and design and a decrease in the performance and reliability of the apparatus. An object of the present invention is to solve such a problem of the prior art, and realizes a circuit configuration of a PLL frequency synthesizer having a small influence on a high-frequency circuit, and realizes a high-performance electronically tuned PLL frequency synthesizer IC or IC .
And a tuner using the same .

[0011]

The tuner of the present invention and the PLL frequency synthesizer of the present invention that achieve the above objects are characterized by a basic oscillation circuit, a variable frequency divider, a phase comparator, a low-pass filter, A control oscillation circuit is integrated in an IC, and first, second, and third terminals are provided, and a basic frequency signal generated by the basic oscillation circuit is frequency-divided by a first frequency division ratio set from outside; The local oscillation frequency signal generated by the voltage controlled oscillation circuit is divided by a second division ratio set from the outside, and these divided signals are compared by a phase comparison circuit so that the comparison result becomes equal. The local oscillation frequency signal for a high-frequency circuit is generated by a PLL that controls the voltage-controlled oscillation circuit, and a first power supply voltage from the outside via a first terminal is supplied to the voltage-controlled oscillation circuit (or the voltage-controlled oscillation circuit). Control circuit and the high-frequency circuit), a second external power supply voltage via a second terminal to the phase comparison circuit, and a third external power supply voltage via a third terminal. Supply to the basic oscillation circuit,
The operating voltage of the phase comparison circuit is the operating voltage of the voltage controlled oscillation circuit.
Operating voltage between the operating voltage and the operating voltage of the basic oscillation circuit.
It works with pressure .

A tuner and a tuner having another configuration according to the present invention.
The characteristic of the PLL frequency synthesizer is that a basic oscillation circuit, a variable frequency dividing circuit, a phase comparison circuit, a low-pass filter, and a voltage controlled oscillation circuit which constitute the PLL are integrated in an IC, and the first, second, and third terminals are integrated. And divides a basic frequency signal generated by the basic oscillation circuit by a first frequency division ratio set from the outside, and converts a local oscillation frequency signal generated by the voltage controlled oscillation circuit into a second division frequency set from the outside. Divide by the circumference ratio,
These frequency-divided signals are compared by a phase comparison circuit, and the local oscillation frequency signal for a high-frequency circuit is generated by a PLL that controls the voltage-controlled oscillation circuit so that the comparison result becomes equal. A first external power supply voltage via a terminal is supplied to the voltage-controlled oscillation circuit (or the voltage-controlled oscillation circuit and the high-frequency circuit), and a second external power supply voltage via a second terminal is supplied to the voltage-controlled oscillation circuit. The voltage is supplied to the phase comparison circuit, and a step-down circuit is connected between the second and third terminals.
A smoothing circuit is connected to the outside through the terminal of the third oscillator, and the voltage of the third terminal is supplied to the basic oscillation circuit as a third power supply voltage.
The operating voltage of the phase comparison circuit is
Between the operating voltage of the circuit and the operating voltage of the basic oscillation circuit.
It operates at the operating voltage .

The tuner of another configuration of the present invention and its PLL frequency synthesizer are characterized by a basic oscillation circuit, a variable frequency dividing circuit, a phase comparison circuit,
A low-pass filter and a voltage-controlled oscillation circuit are integrated in an IC, and first, second, and third terminals are provided, and a basic frequency signal generated by the basic oscillation circuit is converted at an externally set first division ratio. Frequency dividing, dividing a local oscillation frequency signal generated by the voltage controlled oscillation circuit by a second dividing ratio set from outside, and comparing these divided signals by a phase comparing circuit;
The local oscillation frequency signal for a high-frequency circuit is generated by a PLL that controls the voltage-controlled oscillation circuit so that the comparison result becomes equal, and a first power supply voltage from outside via a first terminal is controlled by the voltage control. An oscillator circuit (or the voltage-controlled oscillator circuit and the high-frequency circuit), a first step-down circuit is connected between the first and second terminals, and a first smoothing circuit is externally connected via the second terminal. Is supplied to the phase comparator circuit using the voltage of the second terminal as a second power supply voltage, a second step-down circuit is connected between the second and third terminals, and an external circuit is connected via the third terminal. supplied to the fundamental oscillation circuit voltage of the second third terminal smoothing circuit is connected as a third power supply voltage
The operating voltage of the phase comparison circuit is
Between the operating voltage of the circuit and the operating voltage of the basic oscillation circuit.
It operates at the operating voltage . However, in any of these configurations, a crystal oscillator, a capacitor having a large capacity, a driving transistor having a high speed and a large driving capacity, etc.
Since it cannot be integrated inside, it is attached externally.

[0014]

According to the tuner and the PLL frequency synthesizer of the present invention having the above-described configurations, three terminals are provided.
Different power supply voltages are supplied or generated by step-down. The voltage at one terminal is supplied to the voltage-controlled oscillator circuit, which is relatively high, for example, 9 to 12 V for a high-frequency circuit, and the voltage at the other terminal is lower, for example, about 5 V. The voltage at another terminal is lower than that, for example, about 3 V, and is supplied to the basic oscillation circuit. In this way, the phase comparison circuit operates the voltage-controlled oscillation circuit.
Operates at an intermediate voltage between the operating voltage and the operating voltage of the basic oscillation circuit
Therefore, even if the basic oscillation circuit is set to a low voltage,
The phase comparison circuit acts as an intermediary between the two circuits,
The voltage difference becomes smaller equivalently, and the whole circuit operates in cooperation
can do.

Therefore, the local oscillation frequency signal output from the voltage-controlled oscillation circuit operating at the same power supply voltage as the high-frequency circuit has good compatibility with the high-frequency circuit, and the synthesizer circuit including the phase comparison circuit is used for ordinary digital circuits. It operates with the power supply voltage of, so it has good consistency with the digital circuit that controls external control, etc. In addition, since the voltage difference between the power supply voltage of the synthesizer circuit and that of the voltage-controlled oscillation circuit is not large, a low-pass filter and a voltage-controlled oscillation circuit Can also be driven. Furthermore, since the basic oscillation circuit oscillates at a lower power supply voltage than before, the energy level of the disturbing wave radiated during switching is low, and the power supply voltage difference from the synthesizer circuit is not large, so the basic oscillation circuit Can work with a synthesizer circuit. That is, the PLL frequency synthesizer integrated into an IC according to the present invention can operate in a conventional manner, and has a small undesired effect on the high-frequency circuit.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a PLL frequency synthesizer in a tuner according to the present invention will be described below. FIG. 1 is a block diagram of an electronic tuning circuit as an embodiment to which the PLL frequency synthesizer is applied, and corresponds to FIG. 4 of a conventional example. Here, 1 is a high-frequency circuit, 2 is a basic oscillation circuit, 3 is a synthesizer circuit, 4 is a low-pass filter (LPF), 5 is a voltage controlled oscillation circuit (VCO), and 6 is a microcomputer circuit (MPU).

The electronic tuning PL indicated by a broken line
The L frequency synthesizer IC 70 includes a PL including a basic oscillation circuit 2, a synthesizer circuit 3, an LPF 4, a VCO 5, and the like.
The circuit of the L frequency synthesizer is provided in one IC. However, a crystal oscillator, a capacitor having a large capacity, a driving transistor having a high speed and a large driving capacity, etc.
Since it cannot be converted to C, it is externally attached (a capacitor is shown as a typical example in the figure). In the example of FIG. 1,
As in the conventional example, a frequency mixing circuit 1b, which is a part of the high-frequency circuit 1, is also integrated in the same IC. However, the number of power supply terminals of the IC is increasing, and three kinds of power supply voltages HFVcc, SVcc, and OSCVcc supplied from outside are provided.
In order to receive the signals, three terminals 70a, 70b and 70c are provided.

The high frequency circuit 1 is configured to receive the AM signal received by the antenna.
It receives a high frequency such as a wave or an FM wave and outputs an intermediate frequency signal of a selected frequency. For this purpose, a high frequency amplifier circuit 1a for amplifying the high frequency and a high frequency amplifier circuit 1a for selecting the intermediate frequency signal are provided. A frequency mixing circuit 1b for mixing the local oscillation frequency signal FS with the output is provided. The power supply voltage is typically 9V to 12V.
It operates in response to FVcc. The basic oscillation circuit 2 is configured using a crystal oscillator, and generates a basic frequency signal FB having an accurate period that is hardly affected by a change in temperature or a change with time due to its operation. Since the basic oscillation circuit 2 operates by receiving a power supply voltage OSCVcc of about 3 V as a power supply voltage, noise energy at the time of switching is small and interference with the high-frequency circuit 1 can be reduced.

The synthesizer circuit 3 generates the fundamental frequency signal F
A variable frequency dividing circuit 3a for frequency dividing B, a variable frequency dividing circuit 3b for frequency dividing the local oscillation frequency signal FS, and a phase comparing circuit 3c for comparing phases and periods of these frequency divided signals are provided. . Furthermore, a synthesizer control circuit is provided,
A control parameter or the like from the external MPU 6 is received, and a frequency division ratio or the like in the frequency dividing circuits 3a and 3b is determined accordingly. The power supply voltage is usually about 5 V
, which operates at the same power supply voltage MPUVcc
And the voltage between the power supply voltage HFVcc and the power supply voltage OSCVcc is small, so that the difference between these voltages is small and the basic oscillation circuit 2 and the LPF 4 and VCO 5 can cooperate.

The LPF 4 receives the signal of the comparison result from the phase comparison circuit 3c, removes undesired components on the high frequency side, and generates a control signal to the voltage control oscillation circuit 5. The VCO 5 outputs its own local oscillation signal according to the control signal from the LPF 4, that is, according to the comparison result between the divided signal of the fundamental frequency signal FB and the divided signal of the local oscillation frequency signal FS. The frequency of the frequency signal FS is increased / decreased and controlled so that the comparison result becomes equal. As the power supply voltage operates in response to the same power supply voltage HFVcc as the high-frequency circuit 1, the matching with the high-frequency circuit 1 is good, so that the performance of the high-frequency circuit does not deteriorate.

Although the detailed configuration is omitted in the figure, the MPU 6 usually includes a microcomputer and the like, and also performs input and output for display by operation of the apparatus, and controls necessary control parameters such as frequency division in response thereto. The ratio and the like are set in the synthesizer circuit 3 and the state thereof, for example, whether or not the PLL is locked is monitored. As the power supply voltage, a power supply voltage MPUVcc of about 5 V which is the same as the normal power supply voltage SVcc
It operates in response to it.

Under such a configuration, when a tuning frequency is selected in the MPU 6, the electronic tuning circuit converts a local oscillation signal having an accurate frequency corresponding to the selection from the fundamental frequency signal FB having one accurate frequency. A frequency signal FS can be generated. More specifically, when a tuning frequency is selected in the MPU 6 and one frequency is determined, a corresponding control parameter is set in the synthesizer circuit 3. Thereby, the frequency division ratio in the variable frequency dividing circuits 3a and 3b is determined. In this state, the frequency of the local oscillation frequency signal FS is controlled by the feedback loop formed by the variable frequency dividing circuit 3b, the phase comparing circuit 3c, the LPF 4, and the VCO 5, and the ratio of the dividing ratio to the basic frequency signal FB having the correct frequency is obtained. Local oscillation frequency signal F having a frequency that exactly follows
S is generated. The fundamental frequency signal FB is 10.24 MH
As a specific numerical example of z, when 16.27 MHz is desired for the local oscillation frequency signal FS, the dividing ratios 2048 and 3254 are set for the variable frequency dividing circuits 3a and 3b, respectively, and when 16.725 MHz is desired. Variable frequency divider 3
The frequency division ratios 2048 and 3345 may be set for a and 3b, respectively.

The local oscillation frequency signal FS output from the VCO 5 in this manner is sent to the frequency mixing circuit 1b, where it is mixed with the amplified high frequency and used to select an intermediate frequency signal. Therefore, the electronic tuning circuit using the electronic tuning PLL frequency synthesizer IC 70 having the configuration of the present invention can perform the same signal processing as the conventional one, and furthermore, the interference wave from the basic oscillation circuit 2 to the high frequency circuit 1 is reduced. The performance is improved by the reduced amount. It is not necessary to operate all elements of the synthesizer circuit 3 with the power supply voltage SVcc. For example, the variable frequency dividing circuit 3a and the like use the same power supply voltage OSCVcc as the basic oscillation circuit 2.
The same operation and effect can be obtained by operating the device.

FIG. 2 shows another embodiment of the present invention. The difference from the embodiment of FIG. 1 is that a smoothing circuit including a capacitor Cc and the like is connected to the outside via a terminal 70c. That is, a step-down circuit including a resistor Rc and the like is provided in the IC between the terminal 70b and the terminal 70c. With such a configuration, the power supply voltage OS in the embodiment of FIG.
Since a power supply voltage equivalent to CVcc is supplied to the basic oscillation circuit 2 and the like via the terminal 70c, the operation and effect are exactly the same as those in the above-described embodiment.

FIG. 3 shows another embodiment of the present invention. The difference from the embodiment of FIG. 1 is that a smoothing circuit including a capacitor Cb and the like is connected to the outside via a terminal 70b. And that the capacitor Cc is externally connected through the terminal 70c.
A smoothing circuit composed of a resistor Rb or the like in the IC between the terminal 70a and the terminal 70b, and an IC between the terminal 70b and the terminal 70c.
C has a step-down circuit including a resistor Rc and the like.

With such a configuration, a power supply voltage equivalent to the power supply voltage SVcc in the embodiment of FIG. 1 is supplied to the synthesizer circuit 3 and the like via the terminal 70b, and a power supply voltage equivalent to the power supply voltage OSCVcc is supplied to the terminal 70c. Since it is supplied to the basic oscillation circuit 2 and the like via the element, its operation and effect are exactly the same as those in the above-described embodiment. Note that a reference voltage generating circuit including a zener diode or the like is built in the IC or connected to the terminal 70 in parallel with the built-in step-down circuit or the external smoothing circuit in the above-described other configuration or another configuration of the embodiment.
b and 70c may be connected to the outside.

[0027]

As is apparent from the above description, in the PLL frequency synthesizer having the configuration of the present invention, the power supply voltage of the basic oscillation circuit that switches at high speed and steepness is lowered to lower its operation level, thereby reducing the radiation level. It is possible to suppress an interfering wave caused by a harmonic component which causes an undesired influence due to a wraparound or the like. As a result, a PLL frequency synthesizer with a small effect on high-frequency circuits can be realized, and a high-performance electronically tuned PLL frequency synthesizer IC can be provided. This reduces the number of electronic tuning tuner development design man-hours and improves the performance and reliability of the device. Can also contribute.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic tuning circuit as an embodiment using a PLL frequency synthesizer in a tuner of the present invention.

FIG. 2 is a block diagram of an electronic tuning circuit as another embodiment using a PLL frequency synthesizer having another configuration of the present invention.

FIG. 3 is a block diagram of an electronic tuning circuit as another embodiment using a PLL frequency synthesizer having another configuration of the present invention.

FIG. 4 is a block diagram of an electronic tuning circuit using a PLL frequency synthesizer in a conventional tuner .

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 high-frequency circuit 2 basic oscillator circuit 3 synthesizer circuit 4 low-pass filter circuit 5 voltage-controlled oscillator circuit 6 microcomputer circuit 7 electronic-tuned PLL frequency synthesizer IC 70 electronic-tuned PLL frequency synthesizer IC FB basic frequency signal FS: Local oscillation frequency signal

Claims (3)

(57) [Claims] A frequency division circuit divides a fundamental frequency signal generated by a basic oscillation circuit by an externally set first division ratio, and converts a local oscillation frequency signal generated by a voltage controlled oscillation circuit to an externally set second oscillation frequency. The divided signals are compared by a phase comparison circuit, and the PLL that controls the voltage-controlled oscillation circuit so that the comparison results are equalized. An integrated circuit PLL frequency synthesizer for generating a frequency signal, comprising first, second, and third terminals, wherein a first power supply voltage from the outside via a first terminal is supplied to the voltage-controlled oscillator circuit (or And a second power supply voltage from the outside via a second terminal, which is lower than the first power supply voltage, is supplied to the phase comparison circuit. Third, lower than voltage Supplying a third power supply voltage from an external via the terminal to the fundamental oscillation circuit, said phase
The operating voltage of the comparison circuit is equal to the operating voltage of the voltage-controlled oscillation circuit.
Operating at an operating voltage intermediate between the operating voltage of the
PLL frequency synthesizer which is characterized in that work. 2. The method of claim 1, further comprising: dividing a fundamental frequency signal generated by the basic oscillation circuit by an externally set first frequency division ratio; The divided signals are compared by a phase comparison circuit, and the PLL that controls the voltage-controlled oscillation circuit so that the comparison results are equalized. A tuner including an integrated PLL frequency synthesizer for generating a frequency signal, comprising: a first terminal, a second terminal, and a third terminal, wherein a first power supply voltage from outside via a first terminal is supplied to the voltage-controlled oscillator. Supplying a second power supply voltage from the outside via a second terminal, which is lower than the first power supply voltage, to the phase comparator circuit (or the voltage-controlled oscillation circuit and the high-frequency circuit); 2, the third end A step-down circuit is connected between the terminals, a smoothing circuit is connected to the outside via a third terminal, and the voltage of the third terminal is supplied to the basic oscillation circuit as a third power supply voltage.
The operating voltage of the phase comparison circuit is the operating voltage of the voltage controlled oscillator.
Voltage and the operating voltage of the basic oscillation circuit.
A tuner having a PLL frequency synthesizer operable . 3. The method of claim 1, further comprising: dividing a fundamental frequency signal generated by the basic oscillation circuit by an externally set first frequency division ratio; The divided signals are compared by a phase comparison circuit, and the PLL that controls the voltage-controlled oscillation circuit so that the comparison results are equalized. A tuner including an integrated PLL frequency synthesizer for generating a frequency signal, comprising: a first terminal, a second terminal, and a third terminal, wherein a first power supply voltage from outside via a first terminal is supplied to the voltage-controlled oscillator. Circuit (or the voltage-controlled oscillation circuit and the high-frequency circuit), and a first step-down circuit is connected between the first and second terminals.
A first smoothing circuit is connected to the outside via a terminal of the second stage, and the voltage of the second terminal is supplied to the phase comparison circuit as a second power supply voltage, and a second step-down circuit is provided between the second and third terminals. And a second smoothing circuit is externally connected via a third terminal to supply the voltage of the third terminal as a third power supply voltage to the basic oscillation circuit, and the operating voltage of the phase comparison circuit is Voltage regulation
Operating voltage of the control oscillation circuit and the operating voltage of the basic oscillation circuit.
A tuner having a PLL frequency synthesizer, wherein the tuner operates at an intermediate operating voltage .