JPS6342592Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a square law detector.

Traditionally, high-frequency signal detection has been performed using linear detection and square-law detection using rectifying elements such as diodes. Square-law detection in particular has the property of obtaining an output amplitude proportional to input power, so it is difficult to control the power level. It has been widely used in signal processing equipment.
However, since square law detection utilizes an extremely narrow nonlinear region at the rising edge of the voltage vs. current characteristic of elements such as diodes, good square law detection characteristics can only be obtained in a limited narrow range where the input signal level is relatively low. There were many inconveniences, such as not being able to do so.

This invention eliminates these problems with conventional square-law detectors and makes it possible to attenuate the input signal level in stages so that the input signal level always falls within the square-law detection characteristic region of the diode, resulting in a wide input range. This paper proposes a square-law detector that can obtain the dynamic range of the signal.

FIG. 1 is a block diagram showing one embodiment of this invention. In Fig. 1, 1 is a distributor, 2a, 2b
is a diode detector, 3 is an attenuator, 4 is a selector, and 5 is a comparator.

FIG. 2 is a characteristic diagram showing an example of the relationship between input signals and output signals in the configuration of FIG. 1.

In FIG. 2, 6a and 6b are characteristic curves showing the relationship between the input signal power of the distributor 1 and the output signal amplitude of the diode detectors 2a and 2b. In Figure 2, the horizontal axis indicates the logarithmic intensity (decibel value) of the input power, and the vertical axis indicates the logarithmic intensity (decibel value) of the output amplitude. The area between the dashed line and the broken line parallel to the horizontal axis is the square law detection area used in this embodiment.

Since this invention is constructed as described above, the input signal is equally distributed by the distributor 1 and input to the diode detector 2a and the attenuator 3. The output of the attenuator 3 is further input to a diode detector 2b. The outputs of the diode detectors 2a and 2b are input to the selector 4, and one of them is selected and output according to the control signal from the comparator 5. That is, when the input signal level is low, the input/output characteristics change along the curve 6a, and when the input signal increases and leaves the square law detection region of the diode detector 2a,
The output amplitude at that time is detected by the comparator 5, and the selector 4 output is switched to the diode detector 2b output.
Since the input/output characteristics thereafter change along the curve 6b, the input signal range exhibiting square law detection characteristics is expanded compared to the case where only one diode detector is used.
On the other hand, regarding the absolute value of the output amplitude, although the dynamic range is not expanded as the output amplitude,
Also, if you know how much attenuation is being inserted at that time, you can easily find out. For convenience of explanation, we have used two diode detectors and one attenuator, but any number of diode detectors may be used, and attenuators with different attenuation amounts may be connected in parallel. or several may be connected in cascade to one detector. However, when connected in parallel, it is possible to handle signals with a relatively high data rate, but when connected in cascade, the data rate is slower than that. Further, when using a different number of detectors, it is necessary to provide a somewhat complicated logic circuit in place of the comparator 5, but the basic principle remains unchanged.

As mentioned above, the feature of this invention is that it can handle a wide range of input signals by arranging a combination of a diode detector and an attenuator in parallel and switching them appropriately according to the input level. The point is that square law detection is possible over a wide range.

In addition, as one of the application examples of this invention, A/D
A digital power automatic measurement system can be considered in combination with a converter. That is, general AGC
(Automatic Gain Control) controls the gain of the amplifier before the detector so that the output amplitude is a certain value, and if power information is required, the control signal is used as is, so the linearity becomes a problem. However, according to this invention, the input level is controlled in stages so that the detector output falls within a certain range, so the dynamic range of the output amplitude and the dynamic range of the A/D converter can be reduced. If they match, the input power can be converted into a digital value with good linearity. In addition, for the expansion of the dynamic range of the input signal, the attenuator selection control signal may be used in accordance with the amount of attenuation without changing the bit length of the A/D converter.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of this invention, and Fig. 2 is a characteristic diagram showing an example of the relationship between the input signal and the output signal in the above block diagram, where 1 is a distributor, and 2a and 2b are diode detectors. 3 is an attenuator, 4 is a selector, 5 is a comparator, and 6a and 6b are input/output characteristic curves showing the relationship between the input signal and the diode detector output signal.

Claims (1)

[Scope of utility model registration request] A divider that equally distributes the input signal into two or more, a diode detector that directly squares detects one of the outputs of the divider, and one that attenuates the other output of the divider by a certain amount. Alternatively, a plurality of attenuators, a plurality of diode detectors that are connected to the attenuator and perform square law detection of the output of the attenuator, and a plurality of diode detectors that are connected to the above-mentioned diode detectors and select the output of one of them. and a comparator that generates an input signal selection control signal for the selector based on the output level of the selector.