JPH0470809B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a D/A converter evaluation device, and more specifically, a device suitable for evaluating the dynamic operation of a high-speed D/A converter. It is related to.

(Prior Art) FIG. 4 is a block diagram showing an example of a device for evaluating the dynamic characteristics of a conventional high-speed D/A converter. In FIG. 4, 1 is a pattern generator that generates digital pattern data DT;
D/A converter to be evaluated (hereinafter referred to as D/A converter)
2 to generate digital pattern data DT that can be expected to convert and output a sine wave. 3 is a spectrum analyzer that classifies the frequency components of the analog sine wave signal AS converted and output from the D/A converter 2;

With this configuration, dynamic characteristics of the D/A converter 2 such as glitch, jitter, and linearity can be measured based on the frequency component classification results (frequency spectrum) obtained from the spectrum analyzer.

However, according to such a conventional configuration, it is necessary to use a pattern generator 1 whose output pattern changes faster than the maximum conversion speed of the D/A converter 2.

(Problem to be solved by the invention) However, although a pattern generator can be realized relatively easily in the case of a D/A converter with a relatively slow conversion speed of about 1MHz, If the speed is relatively high, patterns must be generated at an even higher speed, which is extremely difficult.

The present invention has been made with attention to such points, and its purpose is to have a relatively simple configuration,
An object of the present invention is to provide a device that can evaluate the dynamic characteristics of a D/A converter that performs high-speed conversion.

(Means for Solving the Problems) The present invention, which achieves the above object, includes a clock generator that outputs a basic clock for setting operation timing, and a clock generator that generates fixed pattern data fixed at a zero level. a fixed pattern generator that generates sine wave function pattern data that changes in synchronization with the basic clock; and a variable pattern generator that generates sine wave function pattern data that changes in synchronization with the basic clock; It consists of a data selector that adds pattern data complementary to the D/A converter to be evaluated, and a spectrum analyzer to classify the frequency components of the analog signal converted and output from the D/A converter to be evaluated. It is characterized by

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, reference numeral 4 denotes a clock generator that outputs a basic clock CK0 for setting operation timing. A basic clock CK0 output from this clock generator 4 is applied to a timing control circuit 5. A fixed pattern generator 6 generates predetermined fixed pattern data DT2, and its output terminal is connected to one input terminal B of the data selector 7. Reference numeral 8 denotes a variable pattern generator that generates pattern data DT1 that changes according to the clock CK2 synchronized with the basic clock CK0 applied from the timing control circuit 5, and its output terminal is connected to the other input terminal A of the data selector 7. has been done. Data selector 7
is driven according to the clock CK1 synchronized with the basic clock CK0 applied from the timing control circuit 5, and the pattern data of the fixed pattern generator 6 is
Pattern data of DT2 and variable pattern generator 8
DT1 is applied via latch 9 to the D/A converter 2 to be evaluated complementary. Note that a clock CK3 synchronized with the basic clock CK0 is applied to the latch 9 from the timing control circuit 5.

The operation of the device configured in this way will be explained.

FIG. 2 is a timing chart showing the relationship between the clocks output from the timing control circuit 5, where a indicates the reference clock CK0 applied from the clock generator 4 to the timing control circuit 5, and b
indicates the clock CK2 applied from the timing control circuit 5 to the variable pattern generator 8, c indicates the clock CK1 applied from the timing control circuit 5 to the data selector 7, and d indicates the clock applied from the timing control circuit 5 to the latch 9. CK3
It shows.

The fixed pattern generator 6 outputs the fixed pattern data DT2 fixed at zero level to the data selector 7.
Output to input terminal B of. Variable pattern generator 8
outputs the sine wave function pattern data to the input terminal B of the data selector 7 as variable pattern data DT1 that changes sequentially in synchronization with the rising edge of the clock CK2. Data selector 7 is a clock
While CK1 is at H level, variable pattern data DT1 applied from variable pattern generator 8 is selectively output to latch 9, and while CK1 is at L level, fixed pattern data applied from fixed pattern generator 6 is output.
DT2 is selectively output to latch 9. Latch 9
latches the data DT1 or DT2 applied to the latch 9 in a stable state according to the clock CK3, and applies the latched data to the D/A converter 2. That is, clock
The time width of variable pattern data DT1 applied to D/A converter 2 is adjusted according to the duty ratio of CK1.

Therefore, by setting the H level pulse width T of the clock CK1 to a value corresponding to the maximum conversion speed of the D/A converter 2, the response characteristics of the D/A converter 2 can be evaluated. can. and,
Let variable pattern data DT1 be sine wave data,
Since the fixed pattern data DT2 is set to zero level, an analog signal as shown in FIG. 3 is sent from the D/A converter 2 to the spectrum analyzer 3.
AS is added, and the spectrum analyzer 3 can obtain an output in which the frequency components of such an analog signal AS are classified. Based on the frequency spectrum obtained in this manner, dynamic characteristics of the D/A converter 2 such as glitch, jitter, and linearity can be measured as described above.

According to such a configuration, the basic clock CK0
Although high speed is required, the speed of the variable pattern generator 8 may be relatively low, and the entire device can be constructed at relatively low cost.

(Invention and Effects) As explained above, according to the present invention, it is possible to realize a D/A converter evaluation device that can evaluate the dynamic characteristics of a high-speed D/A converter with a relatively simple configuration. The effect is large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
2 is a timing chart showing the relationship between the clocks output from the timing control circuit 5 of FIG. 1, and FIG. 3 is a waveform example diagram of an analog signal output from the D/A converter of FIG. 1, and a drive circuit. FIG. 4 is a block diagram showing an example of a device for evaluating the dynamic characteristics of a conventional high-speed D/A converter. 2... D/A converter to be evaluated, 3... Spectrum analyzer, 4... Clock generator, 5... Timing control circuit, 6... Fixed pattern generator, 7
...Data selector, 8...Variable pattern generator, 9...Latch.

Claims (1)

[Scope of Claims] 1. A clock generator that outputs a basic clock for setting operation timing, a fixed pattern generator that generates fixed pattern data fixed at zero level, and a clock that changes in synchronization with the basic clock. a variable pattern generator that generates sine wave function pattern data, and a D/A converter that is driven in synchronization with a basic clock and that complementarily evaluates the pattern data of the fixed pattern generator and the pattern data of the variable pattern generator. and a spectrum analyzer that classifies the frequency components of the analog signal converted and output from the D/A converter to be evaluated.
A converter evaluation device.