JP4417074B2 - A / D converter with phase adjustment function - Google Patents

Description

The present invention relates to A / D converter with a phase adjustment function of a preferred phase adjustment function A / D converter used in particular to an ultrasonic diagnostic apparatus.

  A general ultrasonic diagnostic apparatus will be described with reference to FIG. The ultrasonic diagnostic apparatus shown in the figure is disclosed in Non-Patent Document 1. In the ultrasonic diagnostic apparatus shown in the figure, the pulse wave output from the transmitter 20 is transmitted toward the diagnosis target via the probe. The echo signal from the diagnosis target is received by the same probe and input to the receiver 30. In the receiver 30, the received signal is amplified and sent to the detector 40. The detector 40 converts the received signal from an analog signal to a digital signal. The digital signal output from the detector 40 is stored in the line memory 50. The data stored in the line memory 50 is read out and stored in the scan conversion memory 60, which is read out and displayed on the display screen 70 or the like.

  By the way, in an ultrasonic diagnostic apparatus, phasing addition is performed about a received signal. This will be described with reference to FIG. As shown in the figure, an echo from a diagnosis target is received by a probe including a plurality of receiving elements 11 arranged in a plurality. The propagation distance of the echo from the diagnosis target differs for each wave receiving element depending on the arrival direction θ. It is therefore necessary to add the pulses received by each element with the same phase. This is called phasing addition. In order to realize this phasing addition, it is necessary to delay the pulse at the Nth receiving element that arrives first among the Nth to -Nth receiving elements, and to reduce the delay amount in order. There is.

That is, the delay amount corresponding to the triangle shown in FIG. With this delay amount, the pulses received by all the receiving elements can be added with the same phase. Now, assuming that the delay amount at the i-th receiving element is t, from the geometrical relationship,
t = {(N + i) psinθ} / c
It becomes. Here, p is an interval between elements, and c is the speed of sound.

  As a method for realizing such phasing addition, there are an analog method and a digital method. In the analog system, an input signal is input through the variable delay element in which the delay amount is set as described above, and converted into a digital signal. For example, as shown in FIG. 8, after the signal received by each receiving element 11 is amplified by the amplifier 2, the analog signal is input to the delay line (DL) 3 as it is. By setting the delay amount of each delay line 3 as described above, an echo signal delayed by an appropriate delay time is converted into a digital signal by the A / D converter 4. By doing so, it is possible to convert ultrasonic waves arriving from directions D1, D2, and D3 in the figure into digital signals that are delayed as indicated by the curves of C1, C2, and C3. Therefore, phasing addition can be realized for ultrasonic waves coming from an arbitrary direction.

On the other hand, in the digital method, digital data obtained by converting an input signal into a digital signal is sequentially stored in a memory, and phase adjustment is performed as described above when reading from the memory. For example, as shown in FIG. 9, after a signal received by each receiving element is amplified by an amplifier 2 and converted into a digital signal by an A / D converter 4, a digital memory corresponding to each receiving element is obtained. Store in 5. Then, data is read from the memory at a position corresponding to the direction of arrival of the ultrasonic wave in each memory. Specifically, phasing addition can be realized for ultrasonic waves coming from the D1 direction by reading data from a memory at a position corresponding to the curve of C1 in the figure and adding them. Similarly, if data is read from the memory at the position corresponding to the curve C2 in the figure and added, the ultrasonic wave coming from the direction D2, and if data is read from the memory at the position corresponding to the curve C3 and added is D3. The phasing addition can be realized for the ultrasonic wave coming from the direction.
Ito Masayasu and Mochizuki Tsuyoshi "Ultrasound Diagnostic Equipment" Corona Inc. August 2002, p. 76-80

In the above-described conventional technology, the above-described analog method or digital method is employed when phasing addition is realized. However, if the above-described method is adopted, a variable delay element and a memory are required, and there is a disadvantage that the number of parts of the ultrasonic diagnostic apparatus increases.
The present invention has been made in order to solve the above-described drawbacks of the prior art, and an object of the present invention is to eliminate the need for the variable delay element used in the analog system when used in an ultrasonic diagnostic apparatus, and in the digital system. by eliminating the need for memory to be used, it is to provide a phase adjustment function a / D converter capable of reducing the hardware amount.

The A / D converter with phase adjustment function according to claim 1 of the present invention is an A / D converter that converts an analog signal input from a probe of an ultrasonic diagnostic apparatus into a digital signal, and has a plurality of phases different from each other A multi-phase generator for generating different types of pulse signals; a selector for selecting the plurality of types of pulse signals generated by the multi-phase generator according to a phase adjustment signal; and the selector for selecting among the plurality of types of pulse signals. An A / D conversion circuit that converts the analog signal into a digital signal using the pulse signal thus formed is formed on one chip, and the multi-phase generator outputs a plurality of types of pulse signals having different phases from each other. The phase difference between the voltage controlled oscillator and one of the outputs of the voltage controlled oscillator and the reference signal And a phase difference detecting circuit for detecting, characterized that you control the oscillation frequency of the voltage controlled oscillator according to the phase difference detected by said phase difference detecting circuit. By using the chip configured as described above, the number of parts of the ultrasonic diagnostic apparatus can be reduced.

According to a second aspect of the present invention, the A / D converter with phase adjustment function according to the first aspect includes a plurality of sets of the selector and the A / D conversion circuit. By using the thus constructed tip, Ru can be further reduced the number of parts of the ultrasonic diagnostic apparatus.

  According to the present invention, by using a multi-phase generator and selector in a single chip for an ultrasonic diagnostic apparatus, the variable delay element used in the analog method and the memory used in the digital method are not required, so the amount of hardware is increased. Can be reduced. Furthermore, according to the present invention, it is possible to maintain the advantage of the high-precision digital system that the phase adjustment can be controlled with high accuracy, and there is an effect that it is not necessary to use an A / D converter that operates at high speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same parts as those in the other drawings are denoted by the same reference numerals.
(Circuit configuration in the chip)
As shown in FIG. 1, a multi-phase generator 41 that outputs a plurality of pulses having different phases from each other, and a plurality of pulses output from the multi-phase generator 41 according to a selection signal SEL for phase adjustment. A phase selector 42 that selects and outputs one pulse, and an analog-to-digital conversion circuit (A / D) 43 that performs a sampling operation at the timing of the pulse selected and output by the phase selector 42 and converts an analog signal into a digital signal. It is comprised including. The multi-phase generator 41, the phase selector 42, and the analog / digital conversion circuit 43 are accommodated in one chip.

A configuration example of the multi-phase generator 41 will be described later. All outputs of the multi-phase generator 41 are input to the phase selector 42.
The phase selector 42 can be configured using a known multiplexer. The phase selector 42 selects and outputs a plurality of pulses input from the multiphase generator 41 according to the contents of the selection signal SEL. The selected pulse is input to the analog-digital conversion circuit 43, and the sampling timing is determined.

The analog-digital conversion circuit 43 receives an analog signal Ain and outputs a digital signal Dout corresponding to the signal level.
Here, the number of chips having the circuit configuration shown in FIG. 1 is prepared corresponding to the number of receiving elements included in the probe. The analog signal received by the wave receiving element corresponding to the probe is converted into a digital signal by the analog-digital conversion circuit 43 in the chip.
Even when a plurality of chips are used, since the same reference signal ADCK is input to each chip, pulses output from each chip have a desired phase difference. Therefore, in the above chip, if an appropriate pulse is selected by the selection signal SEL input to the phase selector 42, the pulse obtained by each receiving element can be converted into a digital signal at an appropriate timing.

(Configuration example of multi-phase generator)
Here, the multiphase generator 41 may be configured as shown in FIG. 2, for example. In the figure, a multi-phase generator 41 corresponds to a phase comparator (PC) 41a that detects a phase difference by comparing phases of an input signal and a reference signal ADCK, and a phase difference detected by the phase comparator 41a. A charge pump circuit (CP) 41b that charges and discharges charge, a loop filter (LF) 41c that filters the output of the charge pump circuit 41b, and a voltage controlled oscillator (VCO) 41d that changes the oscillation frequency according to the output of the loop filter 41c It is comprised including. A part of the output of the voltage controlled oscillator 41d is input to the phase comparator 41a.

As shown in FIG. 3, the voltage-controlled oscillator 41d receives inverters INV-1 to INV-K connected in series in K stages (K is an odd number), and outputs the output of the final stage (Kth stage) to the first. It is configured to connect to the input of the stage. Then, K outputs from each stage become outputs of the multiphase generator 41 and are input to the phase selector 42. In the phase selector 42, only one of the outputs of the above stages is selected and output.
The output of the first stage is input to the phase comparator 41a, and the phase comparator 41a compares the phase of the output of the first stage with the reference signal ADCK. Therefore, since the outputs of the multiphase generator 41 are synchronized with each other, the sampling operation in the analog-to-digital conversion circuit 43 in each chip is performed at the correct timing even when a plurality of the chips are used.

(Multiple circuit configuration on one chip)
By the way, a plurality of the above circuit configurations may be included. That is, as shown in FIG. 4, M (M is a natural number, the same applies hereinafter) phase selectors 42-1 to 42-M and M analog-to-digital conversion circuits (A / D) 43-1 to 43-1. 43-M and the single multiphase generator 41 may be integrated into one chip. In this case, a plurality of sets of phase selectors 42-i (i = 1 to M) and analog-digital conversion circuits 43-i (i = 1 to M) are included in one chip.
Then, a plurality of chips shown in FIG. 4 may be prepared in accordance with the number of receiving elements constituting the probe. Even when a plurality of chips having the circuit configuration shown in FIG. 4 are used, since the same reference signal ADCK is input to each chip, pulses output from each chip have a desired phase difference. Will be. Therefore, even in such a configuration, the sampling operation in the analog-digital conversion circuit 43 in each chip is performed at the correct timing.

(Phase adjustment during transmission)
Although the case where the phase adjustment is performed on the received signal has been described above, the phase adjustment may be performed at the time of transmission. That is, even when the above phase adjustment is performed at the time of transmission, the delay amount can be set correctly. In this case, as shown in FIG. 5, the output of the multi-phase generator 41 is selected by the phase selector 42, and the selected output is transmitted from the probe 10. On the other hand, the signal received by the probe 10 may be converted into a digital signal by the analog-digital conversion circuit 43. The analog-digital conversion circuit 43 operates at a timing based on the reference signal ADCK.

(Ultrasonic diagnostic equipment)
The A / D converter with phase adjustment function described above can be used in an ultrasonic diagnostic apparatus. This ultrasonic diagnostic apparatus using an A / D converter is an ultrasonic diagnostic apparatus having an A / D conversion circuit that converts an analog signal input from a probe into a digital signal. A multi-phase generator that generates a pulse signal; and a selector that selects the plurality of types of pulse signals generated by the multi-phase generator according to a phase adjustment signal. The ultrasonic diagnostic apparatus converts an analog signal input from the probe into a digital signal using the pulse signal thus generated. With this configuration, the variable delay element used in the analog method and the memory used in the digital method are no longer necessary, so the amount of hardware can be reduced. Can be realized. Furthermore, according to the above configuration, it is possible to maintain the advantage of the high-precision digital system that the phase adjustment can be controlled with high accuracy, and therefore it is not necessary to use an A / D converter that operates at high speed.

  As described above, in the present invention, since the multi-phase generator, the phase selector, and the A / D conversion circuit are formed on one chip, a variable delay element and a memory for phase adjustment are not necessary, and a small amount of hardware is required. Thus, phasing addition in the ultrasonic diagnostic apparatus can be realized.

Is a block diagram showing a configuration of a phase adjustment function A / D converter according to an embodiment of implementation that by the present invention. It is a block diagram which shows the structural example of a multiphase generator. It is a block diagram which shows the structural example of a voltage controlled oscillator. It is a block diagram which shows the structure of the A / D converter with a phase adjustment function which provided two or more structures of FIG. It is a block diagram which shows embodiment which adjusts a phase at the time of transmission in the A / D converter with a phase adjustment function by this invention. It is a block diagram which shows the structural example of a general ultrasonic diagnostic apparatus. It is a figure for demonstrating phasing addition. It is a block diagram which shows one structural example for implement | achieving phasing addition. It is a block diagram which shows the other example of a conventional structure for implement | achieving phasing addition.

Explanation of symbols

2 Amplifier 3 Delay line 4 A / D converter 5 Digital memory 10 Probe 11 Receiver element 20 Transmitter 30 Receiver 40 Detector 41 Multiphase generator 41a Phase comparator 41b Charge pump circuit 41c Loop filter 41d Voltage controlled oscillator 42, 42-1 to 42-M Phase selectors 43, 43-1 to 43-M Analog-digital conversion circuit 50 Line memory 60 Scan conversion memory 70 Display screen INV-1 to INV-K Inverter

Claims (2)

An A / D converter that converts an analog signal input from a probe of an ultrasonic diagnostic apparatus into a digital signal,
A multi-phase generator that generates multiple types of pulse signals with different phases,
A selector for selecting the plurality of types of pulse signals generated by the multi-phase generator according to a phase adjustment signal;
An A / D conversion circuit that converts the analog signal into a digital signal using a pulse signal selected by the selector from the plurality of types of pulse signals;
Is formed on one chip,
The multi-phase generator is
A voltage controlled oscillator that outputs a plurality of types of pulse signals having different phases, and a phase difference detection circuit that detects a phase difference between one of the outputs of the voltage controlled oscillator and a reference signal, and is detected by the phase difference detection circuit An A / D converter with a phase adjustment function, wherein an oscillation frequency of the voltage controlled oscillator is controlled according to a phase difference to be performed. 2. The A / D converter with phase adjustment function according to claim 1, comprising a plurality of sets of the selector and the A / D conversion circuit .

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