JPH0984142A - Remote control receiving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a chip area and to save power consumption in comparison with a case providing a constant current circuit at every circuit block by preventing a signal from going around from a filter, a detection circuit and a comparing circuit with large signal amplitude level to a first stage amplifier and a limitter having large gain and reducing a malfunction. SOLUTION: Infrared-ray light 32 is converted into an electric signal by a photoelectric transducer 34, it is amplified by the first stage amplifier 3, amplitude limit is executed by the limitter 4, only a signal component is picked-up by the filter 5, A.C. amplitude is converted into a D.C. level by the detection circuit 6 and the D.C. level is compared with a threshold value by the comparing circuit 7 so as to be outputted in a remote control receiving circuit 10. The circuit 10 controls the power source current of the first stage amplifier 3 and the limitter 4 by a power source current control line 21 outputted from the first constant current circuit 8 and controls the power source current of the filter 5, the detection circuit 6 and the comparing circuit 7 by the power source current control line 22 outputted from the independently provided second constant current circuit 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared remote control device for televisions, videos and the like. More specifically, the present invention relates to an integrated circuit of a remote control receiving circuit that outputs a detection output when infrared rays are received in the remote control device.

[0002]

2. Description of the Related Art Conventionally, in order to supply current and voltage required for the operation of each circuit block in an integrated circuit, for example, "NHK Color Television Textbook (above)" edited by Japan Broadcasting Corporation, Japan Broadcast Publishing Association, 1977, p63-68, etc., various constant current sources and constant voltage sources are used as so-called bias means.

When the bias means are arranged in the integrated circuit most when they are used, one bias means may be provided for each circuit block, and when the least are used, they are arranged in the integrated circuit. Only one bias means needs to be provided. Providing the bias means for each circuit block increases the chip area and power consumption. When a single bias means is used, the chip area and power consumption are small, but interference between circuit blocks easily occurs through the bias means.

[0004]

It is best for the power consumption and the area to use the minimum required number of the bias means in the integrated circuit, but the minimum required number that can prevent the interference between the blocks is. However, there is a problem in that each integrated circuit must be determined depending on the application of the integrated circuit and the performance required from the application.

In view of the problems or problems of the prior art, the present invention is suitable for MOS integrated circuit, and reduces signal sneak due to interference between circuit blocks,
It is an object of the present invention to provide a remote control receiving circuit in which the number of bias means is minimized.

[0006]

In order to solve the above-mentioned problems of the prior art and achieve the object of the present invention, the means shown in FIG. 1 was taken. That is, the remote control receiving circuit 10 according to the present invention
Includes a first constant current circuit 8 and a power supply current control line 21 that is output from the constant current circuit 8 and controls the power supply current of the first stage amplifier 3 and the limiter 4. Further, it is provided with a second constant current circuit 9 and a power supply current control line 22 which is outputted from the constant current circuit 9 and limits the power supply current of the filter 5, the detection circuit 6 and the comparison circuit 7. In the remote control receiving circuit 10, the signal voltage of the input terminal 1 is transmitted at a distance from a standard remote control transmitter up to a practical limit, and when the infrared light 32 is photoelectrically converted by using the standard photoelectric conversion element 34, The minimum number is 10 μVpp. On the other hand, at the input of the comparison circuit 7,
If there is an amplitude of about several hundred mV, output terminal 2 will be High.
It is possible to output a detection output of h or Low level.
Therefore, the amplification factor from the input terminal 1 to the first stage amplifier 3, the limiter 4, the filter 5, and the detection 6 needs to be approximately 10,000 times.

Since the filter 5 also requires a constant input voltage larger than the noise generated inside the filter 5, most of the amplification factor is in the first stage amplifier 3 and the limiter 4.
Must be realized in. Therefore, the first stage amplifier 3 and the limiter 4 have a high amplification factor. In addition to having a high amplification factor for the signal component of the input terminal 1, it also amplifies the interference component from the filter 5, detection circuit 6, and comparison circuit 7 in the subsequent stage with a high amplification factor. Circuit operation tends to be unstable.

In the remote controller receiving circuit 10 shown in FIG. 1, the power supply current control of the first stage amplifier 3 and the limiter 4 having a high amplification factor is performed by the power supply current control line 21 output from the first constant current circuit 8. , The power supply current control of the filter 5, the detection circuit 6, and the comparison circuit 7, which have a relatively low amplification factor,
The power supply current control line 22 output from the constant current circuit 9 of FIG. That is, the power supply current control line 21 of the circuit block having a high amplification factor and the power supply current control line 22 of the circuit block having a low amplification factor are separately provided.

According to the present invention, one constant current circuit 8 is provided for the first stage amplifier 3 having a high amplification factor and the limiter 4,
The power supply current control line 21 controls the power supply current, and one constant current circuit 9 is provided for the filter 5, the detection circuit 6, and the comparison circuit 7 having a low amplification factor, and the power supply current control line 22 controls the power supply current separately. ing. Therefore, the filter 5, the detection circuit 6,
No signal leaks from the comparison circuit 7 to the first stage amplifier 3 and the limiter 4 having a high amplification factor through the power supply current control line. Further, the power consumption and the chip area are smaller than in the case where the constant current circuit is provided in each of the first stage amplifier 3, the limiter 4, the filter 5, the detection circuit 6, and the comparison circuit 7.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a circuit diagram showing a more specific embodiment of the remote control receiving circuit according to the present invention. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals to facilitate understanding.

The remote control receiver circuit 10 includes a first stage amplifier 3,
Limiter 4, filter 5, detection circuit 6, comparison circuit 7,
A first power supply current control line 21 that controls the power supply currents of the first stage amplifier 3 and the limiter 4, a constant current circuit 8 that outputs the first power supply current control line 21, the filter 5, a detection circuit 6, and a comparison. It is composed of a second power supply current control line 22 for controlling the power supply current of the circuit 7 and a constant current circuit 9 for outputting the second power supply current control line 22. For each of the circuit blocks 3 to 9, only the path through which the power supply current flows is shown.

Inside the first constant current circuit 8, a PchMOS transistor (hereinafter referred to as PMOST) is connected to the power supply terminal Vdd.
The source electrode of r) is connected, and the gate electrode of the PMOSTr is commonly connected to the drain electrode and the first power supply current control line 2
1 and one end of the constant current source, and the other end of the constant current source is connected to the ground potential.

Inside the first stage amplifier 3, a plurality of PMOs are provided.
Source electrodes of the STr are commonly connected to the power supply terminal Vdd, and gate electrodes thereof are commonly connected to the power supply current control line 21. The drain electrode of the PMOSTr is connected to the internal circuit of the first stage amplifier 3, and the current supply amount is I
It is A1 and IA2. Since the internal PMOSTr of the first constant current circuit 8 and the PMOSTr of the first-stage amplifier 3 have the same gate-source electrode voltage and constitute a so-called current mirror, the current supply amounts IA1 and IA2 are proportional to the transistor size ratio. Can be set.

Inside the limiter 4, there are n PMOSTs.
The source electrode of r is commonly connected to the power supply terminal Vdd, and the gate electrode thereof is commonly connected to the power supply current control line 21. The drain electrode of the PMOSTr is a limiter 4
Connected to the internal circuit of the
1, IL2, ... ILn. The internal PMOSTr of the first constant current circuit 8 and the PMOSTr of the limiter 4
Since it constitutes a so-called current mirror, the current ratio is the same as the transistor size ratio.

Inside the second constant current circuit 9, the source electrode of the PMOSTr is connected to the power supply terminal Vdd and the PM
The gate electrode of the OSTr is commonly connected to the drain electrode, the second power supply current control line 22 and one end of the constant current source, and the other end of the constant current source is connected to the ground potential.

Inside the filter 5, n PMOSTs are provided.
The source electrode of r is commonly connected to the power supply terminal Vdd, and the gate electrode thereof is commonly connected to the power supply current control line 22. The drain electrode of the PMOSTr is the filter 5
Connected to the internal circuit of the
1, IF2, ... IFn. The internal PMOSTr of the second constant current circuit 9 and the PMOSTr of the filter 5
Since it constitutes a so-called current mirror, the current ratio is the same as the transistor size ratio.

Inside the detection circuit 6, a plurality of PMOSs are provided.
The source electrode of Tr is commonly connected to the power supply terminal Vdd,
The gate electrodes are commonly connected to the power supply current control line 22. The drain electrode of the PMOSTr is connected to the internal circuit of the detection circuit 6, and the current supply amounts are IR1 and IR1, respectively.
It is IR2. Internal PMO of the second constant current circuit 9
Since the STr and the PMOSTr of the detection circuit 6 constitute a so-called current mirror, the current supply amounts IR1, IR
2 can be set in proportion to the transistor size ratio.

Inside the comparison circuit 7, a plurality of PMOSs are provided.
The source electrode of Tr is commonly connected to the power supply terminal Vdd,
The gate electrodes are commonly connected to the power supply current control line 22. The drain electrode of the PMOSTr is connected to the internal circuit of the comparison circuit 7, and the current supply amounts are IC1 and IC1, respectively.
It is IC2. Internal PMO of the second constant current circuit 9
Since the STr and the PMOSTr of the comparison circuit 7 form a so-called current mirror, the current supply amounts IC1, IC
2 can be set in proportion to the transistor size ratio.

At the input terminal 1 of the remote control receiving circuit 10,
As described above, the AC signal having the minimum amplitude of 10 μVpp is input. The input signal is amplified by the first stage amplifier 3 and input to the limiter 4 through the output 11 of the first stage amplifier 3. The limiter 4 limits the amplitude and outputs a signal whose amplitude is limited to a constant value to the output 12 of the limiter 4.
That is, the amplitude of the input signal varies from several tens of μV to a maximum of 100 m depending on the distance between the remote controller transmitter and the remote controller receiving circuit 10.
The output 12 of the limiter 4 always has a constant amplitude even when the output voltage V changes greatly.

The first-stage amplifier 3 and the limiter 4 have a total of about 1000 times to about 5000 times in two stages so that the minimum AC signal amplitude number of 10 μV described above becomes a signal amplitude number of 10 mV or more sufficient for the operation of the filter 5. Has a double amplification factor. The filter 5 extracts only the frequency component of the transmitted signal from the output 12 of the limiter 4 and uses it as the output of the filter 5. Further, the detection circuit 6 converts the AC amplitude value of the output 13 of the filter 5 into a DC level and detects it.
Output 14 of the above. The comparison circuit 7 compares the output 14 of the detection circuit 6 with a predetermined threshold value and outputs a High or Low output to the output terminal 2.

Here, the capacitances 15 to 20 are represented as the capacitance between wirings in the integrated circuit and the capacitance between the gate and drain electrodes of the PMOSTr. Interference due to signal coupling takes place through the capacitors 15-20. Since the first stage amplifier 3 and the limiter 4 have high gains (amplification factors) as described above, when the power supply current control line 21 fluctuates, the capacitance 15,
Of the components 16 and 20, the interference components other than the signal leaked to the input (input terminal 1) of the first-stage amplifier 3 and the input 11 of the limiter 4 are greatly amplified through the capacitors 15 and 20 particularly close to the input side. , Instability such as oscillation is likely to occur. That is, it can be said that the power supply current control line 21 has high sensitivity to interference. Therefore, in order to obtain a stable operation, it is necessary to suppress the fluctuation of the power supply current control line 21 as much as possible.

In the present invention, the power supply current control line 21 and the power supply current control line 22 are independent. Therefore, although the output 13 of the filter 5, the output 14 of the detection circuit 6, and the output 2 of the comparison circuit 7 may change the power supply current control line 22 through the capacitors 17, 18, and 19, the power supply current control line 21 may be changed.
Stable operation can be expected without affecting the.

FIG. 3 is a circuit diagram showing a further embodiment of the remote control receiving circuit according to the present invention. In FIG. 2, the constant current circuit 9 is independent, but in the embodiment of FIG. 3, the constant current circuit 9 is configured to be subordinate to the constant current circuit 8.
The other parts are the same including the fact that the power supply current control lines 21 and 22 are independent of each other. Corresponding parts of the circuits of FIGS. 2 and 3 are given the same reference numerals to facilitate understanding. There is.

In the constant current circuit 9 of FIG. 3, the power supply current control line 21 output from the constant current circuit 8 is connected to the PMOSTr28.
Connected to the gate electrode of. The source electrode of the PMOSTr 28 is connected to the power supply terminal Vdd, and the constant current circuit 8
Since it forms a so-called current mirror with the PMOSTr, the current ratio is proportional to the transistor size.

The drain electrode of the PMOSTr28 is NM
The drain electrode and the gate electrode of the OSTr 30 are commonly connected. Therefore, PMOSTr28 and NMOSTr3
The same current flows through 0. Further, the gate electrode of the NMOSTr30 and the gate electrode of the NMOSTr31 are commonly connected, and the source electrode of the NMOSTr30 and the NMOSTr31 are connected.
The source electrodes of are commonly connected to the ground potential and constitute a so-called current mirror.
The ratio of 0 and the current flowing through the NMOS Tr31 is proportional to the transistor size ratio. .

Further, the drain of the NMOSTr31 is PM
The drain electrode and the gate electrode of the OSTr 29 are commonly connected. Since the source electrodes of the PMOSTr29 are commonly connected to the power supply terminal Vdd, the same current flows through the NMOSTr31 and the PMOSTr29. PMOS
The gate electrode of Tr29 is connected to the power supply current control line 22. The power supply current control line 22 is commonly connected to the gate electrode of the PMOSTr in the filter 5, the detection circuit 6, and the comparison circuit 7, and the PMOSTr constitutes a current mirror together with the PMOSTr 29 in the constant current circuit 9. The current ratio is set by the transistor size ratio.

In FIG. 3, the fluctuation of the power supply current control line 21 is caused by the PMOSTr 28, NMOSTr 30, 31 and PM.
The fluctuation is transmitted in the order of OSTr28, and the power supply current control line 22
Changes. However, the fluctuation of the power supply current control line 22 is P
By changing the gate electrode of the MOSTr29,
Only by increasing the drain current of 29, NMOSTr
The current of 31 does not change, and does not change of the power supply current control line 21. That is, also in the circuit of FIG. 3, the fluctuation of the power supply current control line 21 having high sensitivity to interference can be suppressed. Therefore, stable operation can be expected as in the circuit of FIG.

Various methods of realizing the constant current circuits 8 and 9 are known, but the constant current circuits 8 and 9 can also be realized by the circuit of FIG. 4, for example. P
The current Id flowing through the MOSTr27 is
Assuming that the threshold voltage of Vth is Vth and the resistance value of the resistor 26 is R26, it is well known that Id = Vth / R26 and a constant current value can be set regardless of the power supply voltage, and the power supply voltage fluctuates. The constant current value does not change much. The circuit of FIG. 4 has PMOSTr24 and PMOSTr2 of the same size.
A so-called current mirror is constituted by 7, and the currents flowing through the resistor 26 and the NMOSTr 25 are made equal. NM
When the gate-source electrode voltage of the OSTr25 slightly exceeds the so-called threshold voltage Vth, the NMOSTr25 is turned on and a current flows, and the circuit enters a balanced state. The power supply current control lines 21 and 22 are taken out from the gate electrode of the PMOSTr 27.

[0029]

As described above, according to the present invention, two constant current circuits are provided, and the first constant current circuit controls the power supply current of the first stage amplifier circuit and the limiter circuit having a high gain. The constant current circuit of Fig. 2 constitutes a remote control receiver circuit that controls the power supply current of the subsequent filter circuit, detection circuit, and comparison circuit. Therefore, the chip area and current consumption are smaller than the constant current circuit provided for each circuit block, and there is less interference between the circuit blocks than the case where one constant current circuit is provided for the entire remote control reception circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a remote control receiving circuit according to the present invention.

FIG. 2 is a circuit diagram showing an embodiment of a remote control receiving circuit according to the present invention.

FIG. 3 is a circuit diagram showing an embodiment of a remote control receiving circuit according to the present invention.

FIG. 4 is a constant current circuit applicable to the remote control receiving circuit according to the present invention.

[Explanation of symbols]

1 Input Terminal 2 Output Terminal 3 First Stage Amplifier 4 Limiter 5 Filter 6 Detection Circuit 7 Comparison Circuit 8, 9 Constant Current Circuit 10 Remote Control Receiver 11 Output of First Stage Amplifier 3 12 Output of Limiter 4 13 Output of Filter 5 14 Detection Circuit 6 Output 15, 16, 17, 18, 18, 19, 20 Capacitance 21,22 Power supply current control line 23, 25, 30, 31 N-channel MOS transistor 24, 27, 28, 29 P-channel MOS transistor 26 Resistor 32 Infrared light 34 Photoelectric Conversion element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04B 10/14 10/04 10/06 H04N 5/00

Claims (1)

[Claims] 1. An amplifier circuit which receives infrared light emitted from a transmitter as an electric signal converted by a photoelectric conversion element and amplifies an alternating current component of the inputted electric signal to output the amplified electric signal. A limiter for limiting the amplitude of the output of the amplifier circuit to obtain an output, a filter for selecting an output having a specific frequency from the output of the limiter and providing the output, and converting the AC amplitude value of the output of the filter into a direct current level and outputting it. In the remote control receiving circuit configured by a detection circuit that performs the comparison, and a comparison circuit that compares the output of the detection circuit with the threshold value and outputs the comparison result, the first power supply output from the first constant current circuit. A current control line is commonly connected to the amplifier circuit and the power supply current control line of the limiter, and a second power supply current control line output from a separately provided second constant current circuit is used as the filter, the detection circuit, and the Comparison circuit power Remote control receiver circuit, characterized in that connected in common to a current control line.