JPH0346802A - Compensated detector - Google Patents

Abstract

PURPOSE:To improve the temperature characteristic and the input and output voltage linearly of a detecting circuit by feeding back the output of an operational amplifier to the input side through a circuit having the same constitution as the detecting circuit where the detecting circuit is connected to the input side of the operational amplifier. CONSTITUTION:A high frequency input forming voltage V1 is detected by a diode D1 to flow a current i1 to the input terminal of an operational amplifier OP. On the other hand when a feedback current i2 flow from the output terminal of the operational amplifier OP through the feedback circuit, i1+i2=0 is true because currents are balanced between input terminals of the operational amplifier OP. When diodes D1 and D2 have characteristics equalized and resistors R1 and R2 have the same form and the same resistance value (that is, R1=R2 is true), impedance Z1 and Z2 of the detecting circuit are equal regardless of the change of a temperature (t) or an applied voltage (v). Thus, the change due to the ambient temperature and the linearly dependent upon the input voltage are improved.

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a detector that detects high-frequency human power and converts it into a DC voltage, and in particular its stability against changes in ambient temperature and linearity of input voltage versus output voltage. This invention relates to a detector improved on.

b. Prior Art Conventionally, since this type of detector has temperature characteristics in its circuit, it has been common practice to install the detector in a thermostatic oven in order to stabilize the circuit operation. Ta.

C6 Problems to be Solved by the Invention However, the thermostatic oven is temperature controlled by setting its temperature at approximately 60°C, but if a simple thermostatic oven is used to allow a wide temperature control range, the detection The stability of the detector is affected by the temperature characteristics of the circuit. On the other hand, when the temperature control range of the thermostatic oven is narrowed, there is a problem that the thermostatic oven becomes larger and more expensive.

Further, in the detector, there is a problem that linear detection cannot be performed unless an input voltage with a sufficiently large amplitude is applied in envelope detection.

The present invention has been made in view of the above problems, and its purpose is to provide a compensated wave detector that solves the above problems and improves the temperature characteristics of the wave detection circuit and the linearity between input and output voltages. It is in.

61 Means for Solving the Problems The configuration of the present invention for achieving the above object is that in a detector in which a detection circuit is connected to the input side of an operational amplifier, the detection circuit is connected from the output side of the amplifier to the input side. The present invention is characterized in that it is a compensation type detector in which the temperature characteristic and the linearity between the input and output voltages of the detector circuit are compensated for by feedback through a circuit having the same configuration as the detector circuit.

e. Effect The present invention is constructed as described above, and a circuit consisting of elements having the same circuit constant and the same type as the detection circuit connected to the input side of the operational amplifier is connected as the feedback circuit of the operational amplifier. With respect to a change in ambient temperature, the amount of change in the input side detection circuit element and the amount of change in the circuit element of the feedback circuit are approximately the same. Therefore, the input-side detection circuit is temperature-compensated, and the linearity between the input and output voltages is also compensated.

f. Examples Hereinafter, preferred embodiments of the present invention will be described in detail by way of example based on the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the compensated wave detector of the present invention.
A detection circuit consisting of a diode DI and a resistor R connected to the input side of the amplifier OP, and an element connected from the output side to the input side of the amplifier OP and having the same circuit constant and the same type as the detection circuit, respectively. It consists of a feedback circuit consisting of a diode D2 and a resistor R2. Note that C0 is a capacitor, and 2 is a high frequency power source.

In the figure, the high-frequency input voltage (2) is detected by a diode, and a current 11 flows through the input terminal of the operational amplifier OP. On the other hand, when the feedback current 12 is caused to flow from the output terminal of the amplifier OP through the feedback circuit, 11+1t=Q because the current is balanced at the input terminal of the amplifier OP.

Now, the impedance of the series circuit (detection circuit) of diode D and resistor R1 is Z3, and the impedance of the series circuit (feedback circuit) of diode Dt and resistor R2 is 72.
, the output voltage ■. Then, the impedance of the diodes D, , Dt changes depending on the ambient temperature and also changes with the applied voltage. Therefore, the impedance Z1 of the series circuit of the diode DI and the resistor R1 has a value that changes depending on the ambient temperature and the applied voltage V. This is Z,=f.

(t, v), and similarly impedance Z2 is also Z2
= fz (t, v).

Now, if the diodes D+ and Dz are diodes with the same characteristics, and the resistors R, , R, are of the same type and have the same resistance value, that is, R+ = Rz, then the above-mentioned Zl.

Z2 is equal to:

Zl = fl(t, V)! Zz=ftct,V)−”
'(2) Equation (2) shows that Z and 22 are equal even if the temperature t and the applied voltage V change.

Therefore, by substituting (2) 2 into equation (1), we get: The linearity due to changes due to ambient temperature and input voltage is improved.

[Experiment example]

In the circuit diagram shown in Figure 1, the effect was measured at a frequency of 100MHz and the ambient temperature ranged from 10"C to 50°C.
In the range of , stability and linearity were confirmed as follows.

It was confirmed that the above results showed good characteristics even at a frequency in the 100 kHz band.

FIG. 2 shows another embodiment of the present invention, and is a block diagram of a high frequency stable output power supply device using the compensated detector 1 of the embodiment. In the figure, 5 is a high frequency oscillator, 6 is a power variable device, 7 is a power amplifier, 8 is a load, 9 is a power setting and modulator, and 10 is an error amplifier.

If the compensated detector 1 described in the above embodiment is used for high frequency output stabilization and feedback in the device shown in the same figure, a good high frequency stable output power supply device can be obtained without taking special temperature compensation measures. Can be configured.

Further, since the detector 1 has excellent linearity between input and output voltages, the setting accuracy is improved.

FIG. 3 shows still another embodiment of the present invention, and is a block diagram of a high frequency voltage and power detection device using the compensated detector 1 of the above embodiment.

In the figure, when high frequency power is input to the A terminal, a DC voltage proportional to the high frequency input voltage is obtained at the B terminal, and
When the output DC voltage is squared by the square calculator 12, a DC voltage proportional to the high frequency input power is obtained at the C terminal.

Both output voltages provide stable output even when the ambient temperature of the device changes, and also enable high-frequency voltage detection with excellent linearity and high-frequency power detection with high accuracy.

In view of the above embodiments, the compensated detector of the present invention requires only compensation for the detection diode portion, so it can be used at frequencies ranging from low frequencies to microwaves.

It should be noted that the technology of the present invention is not limited to the technology in the above-mentioned embodiments, and means of other modes that perform the same function may be used, and the technology of the present invention can be modified in various ways within the scope of the above-mentioned configuration. It is possible to add.

g1 Effects of the Invention As is clear from the above description, according to the present invention, in a detector in which a detection circuit is connected to the input side of an operational amplifier, from the output side of the amplifier to the input side, the same configuration as the detection circuit is provided. Since the voltage is fed back through the circuit, the temperature characteristics and linearity between the input and output voltages of the detection circuit can be improved.

Furthermore, since the temperature characteristics have been improved in this way, this detector has the advantage that it does not require the use of a constant temperature bath, which is conventionally required.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the compensated detector of the present invention, and FIG. 2 is a diagram showing another embodiment, and is a block diagram of a high frequency stable output power supply device using the compensated detector of the above embodiment. , FIG. 3 shows still another embodiment, in which the compensated detector 1 of the embodiment
FIG. 2 is a configuration diagram of a high frequency voltage and power detection device using the following. l...Compensated detector, abused capacitor, D +
, Dz...diode, OP... operational amplifier,
R,,R,...Resistor. Figure 1 z2,

Claims (1)

[Claims] In a detector in which a detection circuit is connected to the input side of an operational amplifier, feedback is made from the output side of the amplifier to the input side via a circuit having the same configuration as the detection circuit, A compensated wave detector characterized by compensated temperature characteristics and linearity between input and output voltages.