JPH03210819A - signal generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a signal generator, and is applicable to a measuring device having a measurement item that continuously changes two frequencies with an arbitrary fixed frequency difference. It is about effective techniques.

[Conventional technology]

Synthesized standard signal generators with a single signal output are known as signal generators used to evaluate the characteristics of communication equipment and audio equipment.

[Problem to be solved by the invention]

In measuring the frequency characteristics of an IC having a frequency conversion function, it has become necessary to continuously change two high frequency signals with a certain difference. Two conventional signal generators as described above can be used to generate the two high frequency signals. However, since the two signals are controlled independently, it takes time to set the frequency, making it difficult to measure the characteristics in a short time, and there is a risk of incorrect characteristic evaluation due to frequency setting errors. There are also problems with the reliability of the evaluation.

An object of the present invention is to provide a signal generator with a new function that is convenient for measuring ICs having a frequency conversion function.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a digital arithmetic circuit that receives digital frequency information for setting the main signal and a digital difference signal and performs an addition or subtraction operation, and outputs frequency signals corresponding to the frequency information of the main signal and the output information of the arithmetic circuit, respectively. A main signal generator and a sub signal generator are provided.

〔Example〕

FIG. 1 shows a block diagram of an embodiment of a signal generator according to the present invention.

The main signal frequency signal F1 as a digital signal formed by a switch on an operation panel (not shown) and the difference signal frequency ΔF are inputted in synchronization with respective timing signals CI and C2. The main signal frequency latch captures and holds the main signal frequency signal F1 inputted in synchronization with the timing signal C1. The difference signal frequency launch takes in and holds the difference signal frequency ΔF input in synchronization with the timing signal C2.

The main signal frequency F1 and the difference signal frequency ΔF held in the two latches are input to the addition/subtraction circuit. Although not particularly limited, this addition/subtraction circuit has an addition operation, a subtraction operation, or a function of directly passing through and outputting the input signal on the difference signal frequency ΔF side, depending on the operation mode set by an operation panel (not shown). For example, if the addition/subtraction circuit is set to subtraction mode, it will calculate Fl-ΔF=F2, if addition mode is set, it will calculate F1+ΔF=F2, and if through mode is set, it will calculate ΔF=F2.
shall be.

Main signal frequency Fl held in the main signal frequency latch
is input to a main signal generator, where a main signal f1 is formed in the form of an analog signal having a frequency corresponding to the main signal frequency F1 set in the form of the digital signal.

The sub signal frequency F2 formed by the above addition/subtraction circuit is
The main signal f2 is inputted to the sub-signal generator and is formed as an analog signal having a frequency corresponding to the sub-signal frequency F2 calculated and formed in the form of the digital signal.

FIG. 2 shows a two-signal frequency setting flowchart using the above signal generator.

As an initial setting, when the difference signal frequency ΔF is set and input in synchronization with the timing signal C2, it is held in the difference signal frequency latch circuit.

Next, set the main signal frequency F1 and set the timing signal CI.
When it is input in synchronization with the main signal frequency Fl, it is taken into the main signal frequency launch, and on the other hand, it is transmitted to the main signal generator, where the main signal fl having a frequency corresponding to the main signal frequency Fl is generated.
is formed and output. Further, the main signal frequency F1 captured in the main signal frequency latch and the difference signal frequency ΔF captured in the difference signal frequency latch are supplied to an addition/subtraction circuit. Here, the sub-signal frequency signal F2 added or subtracted according to the operation mode as described above is supplied to the sub-signal generator, and a corresponding frequency signal f2 is formed and output.

Therefore, for the circuit under test having the frequency conversion function as described above, the two frequency signals fl and f as described above are
2 is supplied and its characteristics are measured.

When performing a frequency sweep, return to the step of setting the main signal frequency F1 above and select the next updated main signal frequency F1.
1 is set. By repeating the same operation,
The above characteristic measurement is performed by automatically generating the sub signal f2 corresponding to the sweep of the main signal f1.

In this embodiment, when only the main signal generator is used, it operates as a standard signal generator that generates one frequency signal as in the prior art. Further, since the sub-signal light generator is provided as described above, when the addition/subtraction circuit is set to the through mode, the following operations can be performed. That is, when the addition/subtraction circuit is set to the through mode, it is possible to form a frequency signal f2 having a frequency corresponding to the difference signal frequency ΔF held in the difference signal frequency latch. In this case, the difference signal frequency ΔF held in the difference signal frequency launch is not a difference signal corresponding to the main signal F1 as described above, but is an independent frequency that is desired to be output. In the signal generator of this embodiment, by setting the through mode as described above, it is possible to obtain two frequencies that are generated independently according to the frequency information set in the two launch circuits.

FIG. 3 shows a schematic block diagram of one embodiment of the main signal generator or sub-signal generator.

In this embodiment, a reference frequency oscillation circuit, a phase comparison circuit,
P consists of a voltage controlled oscillator circuit and a variable frequency divider circuit.
A LL circuit is used. That is, the reference frequency signal fo generated by the reference frequency oscillation circuit and the frequency-divided output signal [ol of the variable frequency divider circuit are supplied to the phase comparator circuit. The phase comparison circuit generates a control voltage VC corresponding to the phase difference (frequency difference) between the two signals fo and fo', and controls the oscillation frequency f1 or F2 of the voltage-controlled oscillation circuit. The variable frequency dividing circuit has the oscillation frequency f1 or F2.
Divide the frequency by 1/N. Therefore, both the above signals fo and f
In the PLL locked state where the phase matches with "O", the oscillation frequency f1 or F2 becomes N-fo.The frequency division ratio N of the variable frequency divider circuit is set by
By changing the oscillation frequency f1 or F2 corresponding to these digital signals F1 and F2,
can be obtained. It should be understood that the phase comparison circuit includes a low-pass filter that smoothes the phase comparison output to form the control voltage VC.

Each of the above circuits is provided twice in accordance with the respective input signals Fl, F2 and output signals fl, f2. However, the reference frequency oscillation circuit is shared, and the same reference frequency signal f
o is used. This makes it possible to simplify the circuit and increase relative frequency setting accuracy.

Note that the specific configuration of the main and sub signal generation circuits as described above may be the same as the conventional synthesized standard signal generation circuit described above.

The signal generator of this embodiment may also be composed of two standard signal generators. That is, the standard signal generator on the negative side is provided with a function to send out the set digital signal to the outside, and the other standard frequency generator is provided with the external digital input function and an arithmetic circuit that performs the addition and subtraction operations. It may be installed onboard and selectively generate a frequency signal according to the calculation result.

These standard signal generation circuits can be used independently in normal characteristic tests. When two related signals as described above are generated, they are connected by a signal cable or the like to form a structure similar to that shown in FIG. 1 above. For this reason, for example, one of the standard signal generators mentioned above is set to type A,
It is desirable to make a distinction such as making the other signal generator a B type.

The effects obtained from the above examples are as follows. That is, (11) a digital arithmetic circuit that receives digital frequency information for setting the main signal and a digital difference signal and performs an addition or subtraction operation, and a frequency signal corresponding to the frequency information of the main signal and the output information of the arithmetic circuit, respectively. By providing a main signal generator and a sub-signal generator to output, you can easily generate a main signal corresponding to the frequency information of the main signal and a sub-signal having a frequency with a certain difference by simply inputting the difference signal first. The effect is that it can be formed.

(2) According to (1) above, it is possible to obtain the effect that the characteristics of a device such as an IC having a frequency conversion function can be measured in a short period of time and with high reliability.

(3) By providing a through mode as the operation mode of the addition/subtraction circuit, an effect can be obtained in that an independent frequency signal can also be output from the sub-signal generator.

Although the invention made by the present inventor has been specifically explained based on Examples above, the present invention is not limited to the above-mentioned Examples, and it goes without saying that various changes can be made without departing from the gist thereof. Nor. For example, input means such as switches may be provided for the main signal frequency and the difference signal frequency, respectively. In this case, the first latch circuit can be omitted. The difference signal may be one in which a plurality of signals are stored in a memory circuit, and the difference signal inputted to the addition/subtraction circuit is extracted by specifying the address.Also, the frequency signal specified in the digital signal may be The specific configuration of the signal generator to be formed can take various embodiments.

This invention can be widely used as a signal generator.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows. That is, a digital arithmetic circuit that receives digital frequency information for setting the main signal and a digital difference signal and performs an addition or subtraction operation, and outputs frequency signals corresponding to the frequency information of the main signal and the output information of the arithmetic circuit, respectively. By providing a main signal generator and a sub-signal generator, you can easily generate a main signal corresponding to the frequency information of the main signal and a sub-signal with a fixed frequency difference by simply inputting the difference signal first. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a signal generator according to the present invention, FIG. 2 is a flowchart showing an embodiment of two-signal frequency setting using the above signal generator, and FIG. 1 is a schematic block diagram illustrating one embodiment of a main signal generator or a sub signal generator; FIG. Fl...Main signal frequency, ΔF...Difference signal frequency, C1,
C2...Timing signal, F2...Sub signal frequency, fl
...Main signal frequency signal, f2...Sub signal frequency signal, f
O...Reference frequency signal, VC...Control voltage, fo'...
Divided output

Claims (1)

[Claims] 1. A digital arithmetic circuit that receives digital frequency information for setting the main signal and a digital difference signal and performs an addition or subtraction operation; A signal generator comprising a main signal generator and a sub-signal generator, each of which outputs a corresponding frequency signal. 2. The frequency information and difference signal for setting the above-mentioned main signal shall be inputted in a time-division manner in synchronization with the corresponding timing signals and held in latch circuits provided corresponding to each. A signal generator according to claim 1, characterized in that: 3. The signal generator according to claim 1 or 2, wherein the frequency information of the main signal is swept.