JPH0260232A - A/d conversion circuit - 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 an A/D conversion circuit, and particularly to an A/D conversion circuit that converts an analog signal into a digital signal at high speed and with a wide dynamic range. This relates to conversion circuits.

[Conventional technology]

Figure 5 shows a conventional A/D conversion circuit. In the figure, 1 is a 12-bit A/D conversion circuit that directly samples the input analog signal, converts it into a digital signal, and outputs it. . This method uses an A/D converter with a large dynamic range, that is, an A/D converter with a high number of bits.
A D converter is required.

Next, the operation will be explained.

As shown in Figure 5, the input analog signal is directly converted to 12bit A/D.
The input signal is input to the conversion circuit 6 and a digital signal is output by directly sampling the input signal.

Figure 6 shows the sampling method, where the total amplitude of the input analog signal is n −1+ fl +n+
sampled at intervals of l, V 1% - 1 + V, 1
rV,. , is output as a digital signal. This sampling method is as shown in Figure 6.
For a sampling interval of 1, a dynamic range of V 11@IIK is required, and the A/D conversion circuit 6 requires a high number of bits, so it is inevitably slow.

[Problem to be solved by the invention]

Conventional A/D conversion circuits are configured as described above, so in order to sample the input analog signal, an A/D conversion circuit with a wide dynamic range is required. The number of bits must be increased, and A/
There is a problem in that increasing the number of bits in the D converter slows down the response speed of the circuit.

The present invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide an A/D conversion circuit that can perform A/D conversion at high speed and has a wide dynamic range.

[Means for Solving the Problems] An A/D conversion circuit according to the present invention uses an A/D converter with a small number of bits in order to speed up A/D conversion.
Store the D-converted data in memory and use the D/A
By taking the difference between the converted signal and the input signal to be sampled and A/D converting it, even an A/D converter with a narrow dynamic range can apparently have the same ability as an A/D converter with a wide dynamic range. This configuration constitutes an A/D conversion circuit that performs the following steps.

[Effect]

The A/D conversion circuit in this invention uses an A/D converter with a small number of bits in order to speed up A/D conversion,
Since the sampled data is stored in the memory and the difference from the sampled signal is taken, high-speed, wide dynamic range A/D conversion can be achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an A/D conversion circuit according to an embodiment of the present invention. In the figure, an input analog signal 7 is input to an adder 4 and then to a 3-bit A/D converter 1 having a small number of bits. The digital signal sampled by the 9-bit A/D converter 1 is input to the memory 3 via the adder 4. Memory 3 is designed to store data every time it is sampled (however, at the very beginning, the initial value is stored), and when a new input analog signal v1.1 is received, Memo +7 is stored.
The digital signal v7 stored in step 3 is sent to the 9-bit D/A converter 2, converted into an analog signal v7, and input to the adder 4. Here, subtraction with the input analog signal V□ is performed, and only the difference is A/D converted by the 8-bit A/D converter 1. After the A/D conversion, the required digital signal V n+1 is output by adding it again to the digital signal v7 from the memory 3.

Next, the function and operation will be explained.

In Fig. 1, the input analog signal v7 is 8bitA/
The signal is sampled by the D converter 1 and stored in the memory 3 as a digital signal. Next input analog signal VRiv
When I is input to the adder 4, the digital data contained in the memo +73 is sent to the 3-bit D/A converter 2, where it is converted into an analog signal v7, and the input analog signal V,
+, the difference l v,, +-v71 is 8 b i' t
The signal is input to the A/D converter 1.

That is, in this invention, the signal input to the A/D converter l only needs to have an amplitude of IV,%-r-v-1, and the signal input to the A/D converter l needs to have an amplitude of only IV,%-r-v-1. The device should be able to provide a sufficient dynamic range. The analog signal 1va-+v- is A/D converted by an 8-bit A/D converter 1, and the output digital signal is input to an adder 4, where it is added to the data lV, l stored in the memory 3, and the digital signal 1v7. It is output as I1.

As shown in FIG. 2, the dynamic range of the A/D conversion circuit of this embodiment is the amplitude ■ from the minimum input analog signal V a in to the maximum input analog signal V a i n .

, A/ with an apparent input amplitude of vl'
It has a dynamic range equivalent to that of a D converter. In other words, A/D conversion with a wide dynamic range can be achieved with a high-speed (low bit number) A/D converter.

In the above embodiment, the input analog signal memory is shown as storing only input analog signals at a certain fixed time, but by combining a large number of memories S as shown in FIG. 3, the response of the pulse radar can be adjusted. It can also be applied to a device that detects a signal and performs A/D conversion of the response signal,
Similar effects can be achieved in this case as well.

That is, in another embodiment of the present invention shown in FIG. 3, a memory 5 in which a large number of memories (Ro, Rr, Rz, . . . Rk) are combined is used to transmit data in the video detection of the pulse radar shown in FIG. The amplitude of the echo of the pulse P1 is stored in each memory (Re, Rr, RZ+...R,), for example, the amplitude P after a response time of 11 seconds.

For example, the echo Pg after t1 seconds of the transmitted pulse Pt can be stored in the memory Rx.
The amplitude of ' is determined by the amplitude and P stored in the memory Rx,
This can be obtained by A/D converting only the difference with the amplitude of ', and the A/D conversion output of the response signal of the pulse radar can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, since the number of bits of the A/D converter is reduced and the memory loop is configured, a high speed, wide dynamic range A/D conversion circuit can be obtained. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an A/D conversion circuit according to one embodiment of the present invention, FIG. 2 is a diagram showing a sampling method of an input analog signal according to the present invention, and FIG. 3 is a diagram showing an A/D conversion circuit according to another embodiment of the present invention. 4 is a diagram showing a relationship between a pulse example and a response signal in another embodiment of the present invention, FIG. 5 is a diagram showing a conventional A/D conversion circuit, and FIG. 6 is a diagram showing a conventional A/D conversion circuit. FIG. 2 is a diagram showing a conventional sampling method. 1...8 bit (small number of bits) A/D conversion circuit, 2...8 bit D/A conversion circuit, 3...Memory, 4...Adder, 5...Memory combined with many, 6 ...12bit A/D conversion circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A/D that converts analog signals to digital signals
The conversion circuit includes an A/D converter with a small number of bits, a memory that stores the previous output digital signal, a D/A converter that converts the output of the memory to D/A, and a D/A converter that converts the input analog signal to the above D/A. an adder that subtracts the output of the A converter and inputs it to the A/D converter with a small number of bits; and an adder that adds the output of the A/D converter and the output of the memory to produce an output digital signal. An A/D conversion circuit comprising: