JPH0457241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crystal oscillation circuit, and more particularly to a crystal oscillation circuit that is provided with a current cutoff function to prevent power loss when oscillation is stopped.

[Conventional technology]

FIG. 4 shows a conventional crystal oscillation circuit diagram having an oscillation stop function. Between the oscillation input line 92 and the oscillation output line 93 connected to the crystal oscillator 91,
An oscillation amplification inverter circuit 107 consisting of a P-type MOSFET 94 and an N-type MOSFET 95 is connected.

These P-type MOSFET94 and N-type MOSFET
The gate of each of 95 is connected to the oscillation input line 92 and the drain is connected to the oscillation output line 93. The source and substrate of the P-type MOSFET 94 are connected to a positive power supply 96, and the source and substrate of the N-type MOSFET 95 are connected to GND 97.

In addition, P-type MOSFET98 and N-type MOSFET
A feedback resistor circuit 108 consisting of MOSFET 99 is connected in parallel with the oscillation amplification inverter circuit 107, and these P-type MOSFETs 98 and N-type
The drain of each MOSFET 99 is connected to an oscillation input line 92 and the source is connected to an oscillation output line 93. The gate of P-type MOSFET 98 is connected to GND 101, the substrate is connected to positive power supply 100, and the gate of N-type MOSFET 99 is connected to positive power supply 1.
02, the board is connected to GND103.

Furthermore, the drain of a P-type switching MOSFET 104 having a switching function is connected to the oscillation input line 92, and the source and substrate are each connected to a positive power supply 105. An oscillation stop control terminal 106 is connected to the gate to send a control signal to activate or stop the switching MOSFET 104.

Still another conventional example is shown in FIG. This figure 5 shows the oscillation amplification inverter circuit 107 shown in figure 4.
is replaced with a NAND circuit.

That is, an oscillation amplification NAND circuit 114 is connected between an oscillation input line 112 connected to a crystal oscillator 111 and an oscillation output line 113.
This oscillation amplification NAND circuit 114 has two P-type
MOSFET115,120 and two N type
It is composed of MOSFETs 116 and 118.
First P-type MOSFET 115 and first N-type
The gate of each MOSFET 116 is connected to the oscillation input line 112, and the drain is connected to the oscillation output line 113.

The source and substrate of the first P-type MOSFET 115 are connected to a positive power supply 117, and the source and substrate of the first P-type MOSFET 115 are connected to a positive power supply 117.
The source of MOSFET116 is the second N type
The drain of MOSFET 118 has a second N-type substrate.
It is connected to the substrate of MOSFET 118 and GND 119. The source and substrate of the second P-type MOSFET 120 are connected to a positive power supply 121, and the drain is connected to one end 122 between the drains of the first P-type MOSFET 115 and the first N-type MOSFET 116 and the oscillation output line 113. It is connected to the.

Also, the second P-type MOSFET 120 and the second N
An oscillation stop control terminal 123 is connected to the gate of the MOSFET 118 . For this oscillation amplification
P-type MOSFET 124 in parallel with NAND circuit 114
A feedback resistor circuit 126 composed of an N-type MOSFET 125 is connected. P-type MOSFET 12 that constitutes this feedback resistance circuit 126
The drains of the 4- and N-type MOSFETs 125 are connected to the oscillation input line 112, and the sources are connected to the oscillation output line 113. P type
The gate of MOSFET 124 is connected to GND 129, the substrate is connected to positive power supply 127, and N-type MOSFET 125
Its gate is connected to the positive power supply 130, and its substrate is connected to GND 128.

Although not shown in FIGS. 4 and 5, a first capacitor is connected to the oscillation input line, and a second capacitor is connected to the oscillation output line.

[Problem that the invention seeks to solve]

In the conventional circuit shown in FIG. 4, the oscillation stop control terminal 106 is at the positive power supply voltage level (hereinafter logic "1").
), the switching MOSFET104
becomes non-conductive, and the oscillation section including the oscillation amplification inverter circuit 107 and the feedback resistor circuit 108 performs normal oscillation. Also, the oscillation stop control terminal 10
6 is the GND voltage level (described as logic “0” below)
At this time, the switching MOSFET 104 becomes conductive, and the voltage level of the oscillation input line 92 is fixed to the voltage level "1" of the positive power supply connected to the source and substrate of the switching MOSFET 104.

As a result, the P-type MOSFET 94 constituting the oscillation amplification inverter circuit 107 becomes non-conductive, and the N-type MOSFET 94 becomes non-conductive.
MOSFET95 becomes conductive and the oscillation output line 9
3 is fixed at the voltage level “0” of GND97,
As a result, the oscillation section including the oscillation amplification inverter circuit 107 and the feedback resistor circuit 108 stops oscillating.

At this time, P-type MOSFET98 and N-type
Feedback resistor circuit 10 composed of MOSFET99
Since 8 is always in a conductive state, the N type of the oscillation amplification inverter circuit 107 is in a conductive state.
GND via MOSFET95, feedback resistance circuit 108, and switching MOSFET104
A through current flows between 97 and the positive power supply 105, causing power loss.

On the other hand, in the conventional diagram shown in FIG. 5, the oscillation stop control terminal 123 connects the N-type MOSFET 118
When "1" is applied to the gate of the P-type MOSFET 120, the P-type MOSFET 120 becomes non-conductive, so the P-type MOSFET 115 and the N-type
The MOSFETs 116 and 118 constitute an inverter circuit, which is driven as a normal oscillation circuit. Similarly, when “0” is applied, P-type MOSFET12
0 is conductive and the N-type MOSFET 118 is non-conductive, the oscillation output line 113 is fixed at the voltage level "1" of the positive power supply 121 and oscillation is stopped. At this time, as in FIG. 4, the positive power supply 121 and GND are
(not shown), a through current flowed between the two and a significant power loss occurred.

The present invention has been made in consideration of the above-mentioned circumstances, and it eliminates the flow of through current as in conventional circuits.
An object of the present invention is to provide a crystal oscillation circuit that is improved so that power loss does not occur.

[Means for solving problems]

an oscillation unit having an oscillation input line and an oscillation output line connected to a crystal oscillator, and an oscillation amplification inverting circuit and a feedback resistance circuit connected in parallel between the oscillation input line and the oscillation output line, respectively; The oscillation input line is connected to the oscillation input line, and when the oscillation section is set to an oscillation state, the level of this oscillation input line is set to a first level, and when the oscillation section is set to a stop state, the level of this oscillation input line is set to a first level. a switching circuit for setting the oscillator to a second level, an oscillation stop control means connected to the switching circuit and making the switching circuit conductive or non-conductive, and a means for causing the oscillation section to stop oscillation by the oscillation control means and the switching circuit. The present invention provides a crystal oscillation circuit comprising the oscillation amplification inverting circuit, the feedback resistor circuit, and a current cutoff control circuit that operates to prevent current from flowing in the current path formed in the switching circuit.

[Effect]

In the crystal oscillator circuit configured in this way, a current cutoff control circuit is provided to prevent current from flowing through the current paths formed in the oscillation amplification inverting circuit, the feedback resistor circuit, and the switching circuit when the oscillation circuit stops oscillating. Operate.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A crystal oscillation circuit which is one embodiment of the present invention and improved by the present invention is shown in FIG. 1 and will be described in detail below.

An oscillation amplifying inverter circuit 48 having a P-type MOSFET 34 and an N-type MOSFET 35 is connected between an oscillation input line 32 connected to the crystal oscillator 31 and an oscillation output line 33. These P type
The gates of the MOSFET 34 and the N-type MOSFET 35 are connected to the oscillation input line 32, and the drains are connected to the oscillation output line 33.
The source and substrate of P-type MOSFET 34 are connected to the positive power supply 3
6, the source and substrate of N-type MOSFET 35 are
Connected to GND37.

This oscillation amplification inverter circuit 48 and the feedback resistor circuit are connected in parallel. This feedback resistance circuit includes, for example, a first conductivity type MOSFET, a second conductivity type MOSFET, and a second conductivity type MOSFET.
A transfer gate circuit 49 for feedback resistance consisting of a conductive MOSFET is used.

(In Figure 1, the first conductivity type is P-type MOSFET38,
The second conductivity type is N-type MOSFET 39) This first conductivity type MOSFET 38 and the second conductivity type
The drain of each MOSFET 39 is connected to the oscillation input line 32, and the source of each MOSFET 39 is connected to the oscillation output line 33. Further, the substrate of the first conductivity type MOSFET 38 is connected to the positive power supply 40, and the substrate of the second conductivity type MOSFET 39 is connected to the GND 41.
It is connected to the.

The oscillation unit composed of the inverter circuit 48 for amplifying the oscillation of the crystal oscillator 31 and the transfer gate circuit 49 for the feedback resistor can be configured by connecting capacitors to the oscillation input line 32 and the oscillation output line 33, respectively. It operates as.

Furthermore, a switching circuit having a switching function, for example, a first conductivity type, is connected to the oscillation input line 32.
MOSFET42 is connected. Further, a first terminal 45, a second terminal 46 and a third terminal 4 are connected to the gate of the first conductivity type MOSFET 42 for switching.
The first terminal 4 of the oscillation stop signal control unit 44 having 7
5 is connected, and this oscillation stop signal control section 4
4 two different voltage level signals (positive voltage “1”
1st conductivity type for switching by negative voltage “0”)
MOSFET 42 is controlled.

That is, the first voltage level signal (for example, "0") is applied to the first conductivity type for switching via the first terminal.
When applied to the gate of the MOSFET 42, the first conductivity type MOSFET 42 for switching becomes conductive, and therefore the oscillation input line 32 is connected to the voltage of the positive power supply 43 to which the source and substrate of the first conductivity type MOSFET 42 for switching are connected. fixed at the level. In addition, the P-type MOSFET 34 constituting the oscillation amplification inverter circuit 48 is non-conductive, and the N-type MOSFET 34 is non-conductive.
MOSFET35 becomes conductive, and the oscillation output line 3
3 is fixed at the voltage level of GND 37 connected to the source of N-type MOSFET 35 and the substrate.

As a result, the oscillation section including the crystal oscillator 31, the oscillation amplifying inverter circuit 48, and the feedback resistor transfer gate circuit 49 stops oscillating.

On the other hand, a second voltage level signal (for example, “1”) is sent from the oscillation stop signal control unit 44 via the first terminal 45,
When applied to the gate of the first conductivity type MOSFET 42 for switching, the oscillation input line 32 and the oscillation output line 33 are not fixed at a constant voltage level and are driven as a normal crystal oscillation circuit. By the way, when the oscillation of the oscillation section is stopped, the feedback resistor transfer gate circuit 49 composed of two different conductivity type MOSFETs is always in a conductive state, so that the oscillation amplification inverter circuit is in a conductive state. A through current flows between the positive power supply 43 and GND 37 via the N-type MOSFET 35 of 48, the transfer gate circuit 49 for feedback resistance, and the first conductivity type MOSFET 42 for switching, resulting in significant power loss.

For this purpose, a second terminal 46 that outputs an inverted phase signal of the signal at the first terminal 45, and a third terminal 47 that outputs a signal in the same phase as the first terminal 45 are provided, and the second terminal 46 is connected to a transfer resistor for feedback resistance. Gate circuit 49
The third terminal 47 is connected to the gate of the first conductivity type MOSFET 38 of the transfer gate circuit 4 for feedback resistance.
They are connected to the gates of the second conductivity type MOSFETs 39 of No. 9, respectively, and the through current of the current path is interrupted by controlling the conduction and non-conduction of the feedback resistor transfer gate circuit 49. That is, since the conductivity types of the switching MOSFET 42 and the MOSFET 38 of the feedback resistor transfer gate circuit 49 are the same, voltage level signals that are opposite to each other are always applied to these gates, while the switching MOSFET 42 and the feedback resistor transfer gate circuit 49 have the same conductivity type. Since the conductivity types of the MOSFETs 39 of the transfer gate circuit 49 are different from each other, the same voltage level signal is always given to these gates, so
The conduction and non-conduction of the MOSFETs 38 and 39 are controlled, and as a result, current cutoff control becomes possible.

By providing the oscillation stop signal control section 44 having three terminals in this way, the N-type MOSFET 3 of the oscillation amplification inverter circuit 48 when oscillation is stopped is provided.
5. The through current flowing between the positive power supply 43 and GND 37 via the feedback resistor transfer gate circuit 49 and the first conductivity type switching MOSFET 42 can be cut off, making it possible to prevent significant power loss.

Note that the oscillation stop control section 44 is for switching
The MOSFET is a P-type MOSFET or an N-type MOSFET.
Either MOSFET can control the oscillation of the oscillation section, and can be used in two different ways.
It is possible to control conduction and non-conduction of each MOSFET of the transfer gate circuit 49 for feedback resistance consisting of MOSFETs. The above two examples will be explained below using FIGS. 2 and 3.

Figure 2 shows a P-type switching MOSFET.
This is a crystal oscillation circuit using MOSFET.

The number 51 indicates a crystal oscillator. An oscillation input line 52 and an oscillation output line 53 are connected to this crystal oscillator 51. An oscillation section is connected between these oscillation output lines 52 and 53. The oscillation section includes an oscillation amplification inverter circuit 67 and a feedback resistance transfer gate circuit 68 that are connected in parallel.

As the oscillation amplification inverter circuit 67, for example, the P-type MOSFET 54 and the N-type MOSFET shown in FIG.
An inverter circuit composed of MOSFET 55 is used. P-type MOSFET54 and N-type
The gate of each MOSFET 55 is connected to the oscillation input line 52, and the drain of each MOSFET 55 is connected to the oscillation output line 53. Also, P
The source and substrate of type MOSFET 54 are connected to the positive power supply 56.
In addition, the source and substrate of N-type MOSFET55 are connected to GND.
57.

The feedback resistor transfer gate circuit 68 is
P-type MOSFET58 and N-type MOSFET shown in Figure 2
A circuit composed of MOSFET 59 is used.

The drains of the P-type MOSFET 58 and the N-type MOSFET 59 are connected to the oscillation input line 52, and the sources are connected to the oscillation output line 53.

Also, the substrate of P-type MOSFET 58 is connected to the positive power supply 60, and the substrate of N-type MOSFET 59 is connected to GND 61.
It is connected to the.

As is clear from FIG. 2, a switching circuit 70 having a switching function is connected to the oscillation input line 52. For example, a P-type MOSFET 6 for switching is used as the switching circuit 70.
Use 2. Drain of P-type MOSFET62,
The sources are connected to an oscillation input line 52 and a positive power supply 63, respectively. Further, the substrate of the P-type MOSFET 62 is connected to a positive power supply 63.

Further, an oscillation stop control means 64 is connected to the gate of the switching P-type MOSFET 62. The switching circuit 70 and the oscillation stop control means 64 control driving and stopping of the oscillation section. For example, in the case of the embodiment shown in FIG. 2, two different voltage level signals are sent from the oscillation stop control circuit 64 to the P-type for switching as in FIG.
Applied to the gate of MOSFET62.

When the first voltage level signal (for example, "0") is applied to the gate of the switching MOSFET 62, the switching MOSFET 62 becomes conductive, and the level of the oscillation input line 52 changes to the positive voltage to which the source of the switching MOSFET 62 is connected. The voltage level of the power supply 63 is fixed to "1".
Also, at this time, the N-type MOSFET 55 constituting the oscillation amplification inverter circuit 67 becomes conductive.
The level of the oscillation output line 53 is determined by the N-type MOSFET 5.
The voltage level of GND 57, which is connected to the source of GND 5, is fixed to "0".

As a result, the oscillation section including the crystal oscillator 51, the oscillation amplification inverter circuit 68, and the feedback resistor circuit 69 stops oscillating.

On the other hand, a second voltage level signal (for example, "1") is sent from the oscillation stop control means 64 for switching.
When applied to the gate of MOSFET 62, this switching MOSFET 62 becomes non-conductive. At this time, the voltage levels of the oscillation input line 52 and the oscillation output line 53 are not fixed, and the oscillation section is driven as a normal crystal oscillation circuit.

However, when the first oscillation part stops oscillating, GND57,
A through current flows through the current path consisting of the feedback resistor transfer gate circuit 69 and the positive power supply 63 of the switching circuit 70, but this oscillation stop control section 64
By providing the current cutoff control circuit 69 having the above-mentioned current cutoff control circuit 69, this through current will no longer flow. By the way, in one embodiment of the present invention, the crystal oscillation circuit shown in FIG. 2 is provided with a current cutoff control circuit 69, as is clear from the figure.

This current cutoff control circuit 69 cuts off the through current when the oscillation of the oscillation section is stopped.

That is, the current cutoff control circuit 69 having the oscillation stop control means 64 shown in FIG. type MOSFET58 and N type MOSFET59
Controls conduction and non-conduction. When the oscillation section is in a normal oscillation state (that is, when the signal from the oscillation stop control means 64 is at a positive voltage level), the current cutoff control circuit 69
, a negative voltage level "0" obtained by inverting the phase of the signal from the oscillation stop control means 64 via the inverter circuit 65 is applied to the gate of the P-type MOSFET 58 of the transfer gate circuit 68 for feedback resistance, and N
Oscillation stop control means 6 is attached to the gate of type MOSFET 59.
Apply a positive voltage level signal from 4.

On the other hand, when the oscillation section is in a stopped state (that is, when the signal from the oscillation stop control means 64 is at a negative voltage level), the current cutoff control circuit 69 controls the P of the transfer gate circuit 68 for feedback resistance so that the current is cut off. mold
Oscillation stop control means 64 at the gate of MOSFET 58
A positive voltage level "1", which is obtained by inverting the phase of the signal from the inverter circuit 65, is applied to the N-type
Oscillation stop control means 6 is provided at the gate of MOSFET 59.
A negative voltage level "0" from 4 is applied.

By providing the current cutoff control circuit 69 having the oscillation stop control means 64 in this way, when the oscillation is stopped, the current path formed by the oscillation amplification inverter circuit 67, the feedback resistor transfer gate circuit 68, and the switching circuit 70 is No through current flows, preventing significant power loss.

In FIG. 3, an N-type MOSFET 80 is used as a switching circuit 85, unlike the P-type MOSFET 62 used as the switching circuit 70 in FIG. The source and drain of this N-type MOSFET 80 are the oscillation input line 52 and GND8, respectively.
Connected to 1. Also, the switching N
The gate of the type MOSFET 80 is controlled by an oscillation stop control means 64. The switching circuit 85 and the oscillation stop control means 64 control driving or stopping of the first oscillation section. Similar to FIG. 3, two different voltage level signals are applied from the oscillation stop control means 64 to the gate of the switching MOSFET 80.

When the first voltage level signal (for example, "0") is applied to the gate of the switching MOSFET 80, the switching MOSFET 80 becomes non-conductive. At this time, the voltage levels of the oscillation input line 52 and the oscillation output line 53 are not fixed, and the oscillation section is driven as a normal crystal oscillation circuit.

On the other hand, a second voltage level signal (for example, "1") is sent from the oscillation stop control means 64 for switching.
When applied to the gate of MOSFET 80, this switching MOSFET becomes conductive, and the level of oscillation input line 52 becomes switching
GND8 where the source of MOSFET80 is connected
It is fixed at the voltage level "0" of 1. Also, at this time, the oscillation amplification inverter circuit 67 is configured,
The P-type MOSFET 54 becomes conductive, and the level of the oscillation output line 53 is fixed to the voltage level "0" of the positive power supply 56 connected to the source of the P-type MOSFET 54.

As a result, the oscillation section consisting of the crystal oscillator 51, the oscillation amplification inverter circuit 67, and the feedback resistor circuit 38 stops oscillating.

The oscillation stop control means 64 shown in FIG. 2 is provided. The current cutoff control circuit 84 uses the control signal from the oscillation stop control means 64 to control the P-type MOSFET 58 that constitutes the feedback resistance circuit 68.
and controls conduction and non-conduction of the N-type MOSFET 59. This current cutoff control circuit 84 operates when the oscillation section is in a normal oscillation state (that is, when the signal from the oscillation stop control means 64 is at the positive voltage level "1").
N type of transfer gate circuit 68 for feedback resistor
A positive voltage level “1” is applied to the gate of the MOSFET 59, and a negative voltage level “0” is applied to the gate of the P-type MOSFET 58 by inverting the phase of the signal from the oscillation stop control means 64 via the inverter circuit 82.
Apply. As a result, the N-type MOSFET 5 configuring the transfer gate circuit 68 for feedback resistance
9 and P-type MOSFET 58 are in a conductive state. On the other hand, when the oscillation section is in a stopped state (that is, when the signal from the oscillation stop control means 64 is at a negative voltage level of "0"), the current cutoff control circuit 84 uses a feedback resistor transfer gate circuit to cut off the current. A positive voltage level "0" is applied to the gate of the N-type MOSFET 59 of 68, and a positive voltage level "1" is applied to the gate of the P-type MOSFET 58 by inverting the phase of the signal from the oscillation stop control means 64 via the inverter circuit 82. Apply.

As a result, the N-type MOSFET 59 and the P-type MOSFET 59 constituting the transfer gate circuit 68 for feedback resistance
MOSFET 58 becomes non-conductive.

By providing the current cutoff control circuit 84 having the oscillation stop control means 64 in this manner, when the oscillation is stopped, the current cutoff control circuit 84 is formed by the oscillation amplification inverter circuit 67, the feedback resistance transfer gate circuit 68, and the switching N-type MOSFET 80. No through current flows through the current path, and significant power loss can be prevented. In addition, since the oscillation amplification inverter circuit and transfer gate circuit used in Figures 2 and 3 are equivalent to conventional crystal oscillation circuits, the circuit constants can be easily set and the oscillation accuracy can be improved compared to conventional ones. can be kept. Furthermore, since the number of elements is kept to a minimum, the area occupied by the lip does not become large when it is integrated into an integrated circuit.

The oscillation section, which consists of the crystal oscillator, oscillation amplification inverter circuit, and feedback resistor transfer gate circuit shown in Figures 3 and 4, can be operated by connecting capacitors to the oscillation input line and oscillation output line, respectively. Drives as a crystal oscillation circuit.

〔Effect of the invention〕

According to the present invention, it is possible to provide a crystal oscillation circuit that can block through current generated when oscillation is stopped and prevent power loss with an extremely simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a crystal oscillation circuit diagram showing an embodiment of the present invention, FIGS. 2 and 3 are crystal oscillation circuit diagrams showing a specific example of FIG. This is a conventional example. 31...Crystal oscillator, 32...Oscillation input line, 33...Oscillation output line, 34, 38, 42
...P type MOSFET, 35, 39...N type
MOSFET, 36, 40, 43...Positive power supply, 3
7, 41...GND, 44...Oscillation stop signal control unit, 49...Feedback resistance circuit, 70, 85...Switching circuit.

Claims (1)

[Claims] 1. An oscillation input line connected to one end of the crystal oscillator, an oscillation output line connected to the other end, and an oscillation amplification line connected between the oscillation input line and the oscillation output line. an inverter circuit; a first conductivity type having a drain connected to the oscillation input line and a source connected to the oscillation output line;
a feedback resistor transfer gate circuit comprising a MOSFET and a second conductivity type MOSFET whose drain is connected to the oscillation input line and whose source is connected to the oscillation output line; and a first conductivity type MOSFET whose drain is connected to the oscillation input line. A type switching MOSFET, a first terminal connected to the gate of the first conductivity type switching MOSFET, and a first conductivity type MOSFET of the feedback resistor transfer gate circuit.
a second terminal connected to the gate of the feedback resistor and a second conductivity type of the feedback resistor transfer gate circuit;
an oscillation stop signal control section having a third terminal connected to the gate of the MOSFET, and the oscillation stop signal control section includes a transfer gate circuit for the gate of the first conductivity type switching MOSFET and the feedback resistor. the second conductivity type of
A crystal oscillation circuit characterized in that a same phase signal is applied to the gates of the MOSFETs, and an inverted phase signal of the same phase signal is applied to the gates of the first conductivity type MOSFETs of the feedback resistor transfer gate circuit.