KR101056015B1 - Time-to-Digital Converters and Time-to-Digital Conversion Methods for Higher Order Noise Shaping - Google Patents

Abstract

A time-to-digital converter capable of secondary noise shaping is a first digital signal obtained by digitizing a time interval between the first digital input signal and the second digital input signal in response to a first digital input signal and a second digital input signal. Amplifying a digital output signal and a time interval corresponding to the quantization error caused by the digitization to generate a first time interval output signal and a second time interval output signal having the amplified time interval between rising edges. A first time-digital converter configured to digitize a time interval between the first time interval output signal and the second time interval output signal in response to the first time interval output signal and the second time interval output signal; A second time-to-digital converter for generating a second digital output signal and the second digital output signal and the first digital; In response to the output signal it includes a second order noise shaping to produce a converted signal converted signal.

Description

Time-to-DIGITAL CONVERTER WITH HIGH ORDER NOISE-SHAPING AND METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-to-digital converter (TDC), and more particularly, to enable high-order noise shaping using a gated-ring oscillator (GRO). A time-to-digital converter and a time-to-digital conversion method.

As semiconductor process technology advances, the transition time of digital signals decreases, increasing the time-based resolution. Accordingly, researches on circuits that operate on a time basis and on performance improvement of time-to-digital converters are being actively conducted.

As a method for improving the performance of a time-to-digital converter by reducing a quantization error, a time-digital converter capable of primary noise shaping using an open / close ring oscillator is known. In the case of using the first-order noise-shaping time-digital converter as described above, quantization noise may be relatively reduced in a low frequency band. However, as more and more demanding systems are required, it is necessary to further reduce the quantization noise of the time-to-digital converter.

In order to reduce the quantization noise, the oscillation frequency used in the switching oscillator should be increased to make the minimum usable time interval smaller. However, increasing the oscillation frequency increases power consumption and makes circuit design difficult.

Accordingly, one object of the present invention is to provide a time-to-digital converter that simultaneously provides a time-digitized digital output signal and quantization error information.

One object of the present invention is to provide a time-to-digital converter capable of high order noise shaping.

An object of the present invention is to provide a time-to-digital conversion method capable of high order noise shaping.

In order to achieve the above object of the present invention, a time-to-digital converter for simultaneously providing a digitized digital output signal and quantization error information according to an embodiment of the present invention is a first digital input signal and a second digital input An enable signal generator that generates an enable signal that is enabled during a time interval from a rising edge of the first digital input signal to a rising edge of the second digital input signal in response to the signal; An open / close ring oscillator for generating an oscillation signal in response to an enable signal, a counter for generating a digital output signal corresponding to the number of rising edges of the oscillation signal in response to the oscillation signal, and the enable signal and the oscillation signal A first time interval output signal and a second time interval having a time interval between rising edges It includes an amplifier for generating a time output signal.

In an embodiment, the time amplifier further comprises a time interval between rising edges of the first time interval output signal and the second time interval output signal from the last rising edge of the oscillation signal to the falling edge of the enable signal. The time interval may correspond to the amplified time interval.

In order to achieve the above object of the present invention, the second-order noise-shaping time-to-digital converter according to an embodiment of the present invention is the first digital input in response to the first digital input signal and the second digital input signal A first time having the amplified time interval between rising edges by amplifying a time interval corresponding to the digitization error caused by the digitization and the first digital output signal which is digitized the time interval between the signal and the second digital input signal A first time-digital converter for generating an interval output signal and a second time interval output signal, the first time interval output signal and the second in response to the first time interval output signal and the second time interval output signal; A second time-digital converter for generating a second digital output signal obtained by digitizing the time interval between the time interval output signals The second by a digital output signal and responsive to the first digital output signal and comprising a second order noise shaping to produce a converted signal converted signal.

In example embodiments, the first time-to-digital converter may be configured from the rising edge of the first digital input signal to the rising edge of the second digital input signal in response to the first digital input signal and the second digital input signal. A first enable signal generator for generating a first enable signal enabled during a time interval, a first open / closed ring oscillator for generating a first oscillation signal in response to the first enable signal, and in response to the first oscillation signal A first counter for generating the first digital output signal corresponding to the number of rising edges of the first oscillation signal and a time interval between the rising edges in response to the first enable signal and the first oscillation signal. And a time amplifier to generate the first time interval output signal and the second time interval output signal, wherein the second time-de The hair converter is enabled during the time interval from the rising edge of the first time interval output signal to the rising edge of the second time interval output signal in response to the first time interval output signal and the second time interval output signal. A second enable signal generator for generating a second enable signal, a second open / close ring oscillator for generating a second oscillation signal in response to the second enable signal, and the second oscillation signal in response to the second oscillation signal And a second counter for generating the second digital output signal corresponding to the number of rising edges of the second digital output signal.

In an embodiment, the time amplifier is further configured such that a time interval between rising edges of the first time interval output signal and the second time interval output signal is equal to that of the first enable signal from the last rising edge of the first oscillation signal. The time interval to the falling edge may correspond to the amplified time interval.

The signal converting unit may include a time delay unit generating a time delayed signal by one sampling period in response to the second digital output signal, the second digital output signal, and the second delayed signal in response to the time delayed signal. A first adder and a subtractor for generating a subtracted output signal by subtracting the time delayed signal from a digital output signal, a gain amplifier for amplifying the subtracted output signal to produce an amplified signal and the first amplified signal and the first digital signal; And a second adder to add the output signals to generate the second noise-shaped converted signal.

In an embodiment, the amplification gain of the gain amplifier may be the inverse of the amplification gain of the time amplifier.

In order to achieve the above object of the present invention, a time-to-digital converter capable of shaping N (N is an integer of 3 or more) according to an embodiment of the present invention includes: a first time-digital converter to N-time- N time-digital converters constituted by a digital converter, and (N-1) signal converters constituted by the first to (N-1) th signal converters.

Each of the N time-to-digital converters is a digital output signal and the digitization in which a time interval between the first digital input signal and the second digital input signal is digitized in response to a first digital input signal and a second digital input signal. Amplifying a time interval corresponding to the quantization error by to generate a first time interval output signal and a second time interval output signal having the amplified time interval between rising edges, wherein a (a is (N− 1) a positive integer below) The first time interval output signal and the second time interval output signal of the time-digital converter are respectively the first digital input signal and the (a + 1) time-digital converter; Is connected to become a second digital input signal.

Each of the (N-1) signal converting units generates one converted signal in response to a first signal converting input signal and a second signal converting input signal, and the (N-1) signal converting unit generates the Nth converting signal. Receiving the digital output signal of the time-to-digital conversion unit as the first signal conversion input signal and receiving the digital output signal of the (N-1) time-digital conversion unit as the second signal conversion input signal and -1) generates a converted signal, wherein the k-th (k is a positive integer less than (N-2)) signal conversion unit to the output signal of the (k + 1) signal conversion unit to the first signal conversion input signal Receive the digital output signal of the k-th time-digital conversion unit as the second signal conversion input signal to generate a k-th conversion signal.

In example embodiments, each of the N time-digital converters may include a rising edge of the second digital input signal from a rising edge of the first digital input signal in response to the first digital input signal and the second digital input signal. An enable signal generator that generates an enable signal that is enabled for a time interval up to an open / closed ring oscillator that generates an oscillation signal in response to the enable signal, and a number of rising edges of the oscillation signal in response to the oscillation signal; A counter for generating the corresponding digital output signal and a time for generating the first time interval output signal and the second time interval output signal having a time interval between rising edges in response to the enable signal and the oscillation signal; It may include an amplifier.

In an embodiment, the time amplifier is configured such that a time interval between rising edges of the first time interval output signal and the second time interval output signal is the time from the last rising edge of the oscillation signal to the falling edge of the enable signal. It can be made to correspond to the time interval amplified interval.

In example embodiments, each of the (N-1) signal conversion units may include a time delay unit generating a time delayed signal by one sampling period in response to the first signal conversion input signal, the first signal conversion input signal, and A first amplifier for subtracting the time delayed signal from the first signal conversion input signal in response to the time delayed signal to produce a subtracted output signal, and a gain amplifier for amplifying the subtracted output signal to provide an amplified signal And a second adder / subtractor for adding the amplified signal and the second signal conversion input signal to provide the converted signal.

In an embodiment, the amplification gains of the respective gain amplifiers are equal to each other, the amplification gains of the respective time amplifiers are equal to each other, and the amplification gains of the respective gain amplifiers are inverse of the amplification gains of the respective time amplifiers. Can be.

In order to achieve the above object of the present invention, the second-order noise-shaping time-to-digital conversion method according to an embodiment of the present invention is the first digital input signal and the second digital input signal in response to the first Generating a first enable signal that is enabled during a time interval from the rising edge of the digital input signal to the rising edge of the second digital input signal, responding to the first enable signal using a first open / close oscillator. Generating a first oscillation signal, generating a first digital output signal corresponding to the number of rising edges of the first oscillation signal in response to the first oscillation signal, the first enable signal and the first The time interval between rising edges in response to the first oscillation signal is equal to the first enable signal from the last rising edge of the first oscillation signal. Generating a first time interval output signal and a second time interval output signal to correspond to a time interval obtained by A times amplification of the time interval to the falling edge, the first time interval output signal and the second time interval output signal In response, generating a second enable signal that is enabled during a time interval from the rising edge of the first time interval output signal to the rising edge of the second time interval output signal, using the second open / close ring oscillator. Generating a second oscillation signal in response to a second enable signal; generating a second digital output signal corresponding to the number of rising edges of the second oscillation signal in response to the second oscillation signal; Generating a signal delayed by one sampling period in response to the two digital output signals, the second digital output signal and the time Generating a subtracted output signal by subtracting the time delayed signal from the second digital output signal in response to the delayed signal, generating an amplified signal by amplifying the subtracted output signal by 1 / A times; and Summing the amplified signal and the first digital output signal to produce a secondary noise shaped signal.

Hereinafter, a time-digital converter and a time-digital conversion method capable of high-order noise shaping according to embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is limited to the following embodiments. Those skilled in the art will appreciate that the present invention may be embodied in various other forms without departing from the spirit of the invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof. Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

On the other hand, when an embodiment is otherwise implemented, a function or operation specified in a specific block may occur out of the order specified in the flowchart. For example, two consecutive blocks may actually be performed substantially simultaneously, and the blocks may be performed upside down depending on the function or operation involved. Like reference numerals in the drawings denote like elements.

1 is a block diagram illustrating a conventional open / close ring oscillator based time-to-digital converter. Referring to FIG. 1, the conventional open / close ring oscillator-based time-to-digital converter 100 includes an enable signal generator (Enable Generator) 110, a closed ring oscillator (GRO) 120, and a counter. 130. The enable signal generator 110 receives two signals START and STOP to be compared to generate an enable signal EN. The open / close ring oscillator 120 generates an oscillation signal GRO_OUT in response to the enable signal EN. The counter 130 generates a digital output signal y [n] in response to the oscillation signal GRO_OUT.

FIG. 2 is a simulation diagram of the conventional open / close ring oscillator based time-to-digital converter 100 of FIG. 1.

Hereinafter, the operation of the conventional open / close ring oscillator based time-to-digital converter 100 will be described in detail with reference to FIGS. 1 and 2.

As shown in FIG. 1, the enable signal generator 110 receives the two signals START and STOP to be compared, and as shown in FIG. 2, a rising edge of the START signal. Generate the enable signal EN that is enabled during the time interval from < RTI ID = 0.0 > As shown in FIG. 2, the open / close ring oscillator 120 oscillates only when the enable signal EN is logic 'high' and oscillates when the enable signal EN is logic 'low'. Stops, stores the previous phase information and starts oscillating again from the phase state when the enable signal EN becomes logic 'high' again. The counter 130 provides the digital output signal y [n] by counting the number of rising edges of the oscillation signal GRO_OUT, which is an output signal of the open / close ring oscillator 120, at each sampling period.

As shown in FIG. 2, the open / close ring oscillator 120 increases the phase of the oscillation signal GRO_OUT when the enable signal EN is logic 'high'. When the enable signal EN is logic 'low', the phase of the oscillation signal GRO_OUT is maintained in the current state, so that the quantization error during the previous sampling period becomes the initial phase of the current sampling period, and thus the digital output signal y [n]) may be expressed as Equation 1 below.

[Equation 1]

y [n] = x [n] + p ₀ [n]-e [n]

     = x [n] + e [n-1]-e [n]

Where y [n] represents the digital output signal of the counter 130, x [n] represents the phase changed by the open / close ring oscillator 120, and e [n] represents the quantization error at time n , e [n-1] represents the quantization error at time n-1, p ₀ [n] represents the initial phase at time n, and p ₀ [n + 1] represents time (n + 1) Initial phase at

Z-transformation of Equation 1 is expressed as Equation 2 below.

[Equation 2]

Y (z) = X (z) + z ^-1 E (z)-E (z)

= X (z) + (z ^-1-1 ) E (z)

From Equation 2, the time-digital converter 100 of FIG. 1 has a noise transfer function having a high pass characteristic as shown in Equation 3 below. It can be seen.

&Quot; (3) "

N _TF (z) = z ^-1-1

Accordingly, the open / close ring oscillator-based time-to-digital converter 100 as shown in FIG. 1 has a primary noise shaping characteristic.

The present invention provides a time-to-digital converter having a high-order noise shaping characteristic by using a ring-shaped oscillator-based time-to-digital converter having primary noise shaping characteristics as described above.

3 is a block diagram illustrating a modified open / close ring oscillator based time-to-digital converter according to an embodiment of the present invention.

Referring to FIG. 3, the modified open / close ring oscillator-based time-to-digital converter 300 includes an enable signal generator 110, an open / close ring oscillator 120, a counter 130, and a time amplifier 340. Include. The enable signal generator 110 receives two signals START and STOP to be compared to generate an enable signal EN. The open / close ring oscillator 120 generates an oscillation signal GRO_OUT in response to the enable signal EN. The counter 130 generates a digital output signal y [n] in response to the oscillation signal GRO_OUT. The time amplifier 340 generates two signals START_d and STOP_d in response to the enable signal EN and the oscillation signal GRO_OUT.

FIG. 4 is a simulation diagram of the modified open / close ring oscillator based time-to-digital converter of FIG. 3.

Since the modified open / close ring oscillator of FIG. 3 adds the time amplifier 340 to the open / close ring oscillator of FIG. 1, the enable signal generator 110, the open / close ring oscillator 120, and the counter 130 Since the operation has been described in detail above, only the operation of the time amplifier 340 will be described in detail here with reference to FIGS. 3 and 4.

As shown in FIG. 4, the time amplifier 340 has a falling edge of the enable signal EN from the last rising edge of the oscillation signal GRO_OUT corresponding to the quantization error of the time-digital converter 300. Amplifying the time interval up to generates the two output signals START_d and STOP_d having a time interval between the rising edges by the amplified time. Accordingly, the modified open / close ring oscillator-based time-to-digital converter 300 shown in FIG. 3 may simultaneously provide error information according to quantization as well as the digital output signal y [n] digitized in time.

5 is a block diagram illustrating a time-to-digital converter capable of secondary noise shaping according to an embodiment of the present invention.

Referring to FIG. 5, the time-digital converter 500 capable of secondary noise shaping may include a first time-to-digital converter (1st TDC) 510 and a second time-digital converter. (second time-to-digital converter, 2nd TDC) 520 and a signal converter 530.

The first time-digital converter 510 receives two signals START and STOP to be compared and digitizes the digital output signal Y _{1 obtained} by digitizing the time interval between the two signals and the quantization by the digitization. The time interval corresponding to the error is amplified by A times to generate two output signals START_d and STOP_d having a time interval between the rising edges by the amplified time.

The second time-digital converting unit 520 receives the two output signals START_d and STOP_d of the first time-digital converting unit 510 as an input signal, and between the two signals START_d and STOP_d. A digital output signal (Y ₂ ) digitizing the time interval of the A and the time interval corresponding to the quantization error by the digitization is amplified by A times to generate two output signals having a time interval between the rising edges by the amplified time. do.

The signal converter 530 receives the output signal Y ₂ of the second time-digital converter as a first signal conversion input signal and receives the output signal Y ₁ of the first time-digital converter. Received as a transformed input signal to generate a second noise shaped transformed signal (Y). The signal converter 530 may time delay the first signal conversion input signal by one sampling period to generate a time delayed signal, the first signal conversion input signal, and the time delayed signal. A first subtractor 533 that receives and subtracts the time delayed signal from the first signal conversion input signal to generate a subtracted output signal, and amplifies the subtracted output signal by 1 / A times to generate an amplified signal A gain amplifier 535 and a second adder and drop 537 for generating the second noise-shaped converted signal Y by adding the amplified signal and the second signal converted input signal.

The first time-digital converter 510 and the second time-digital converter 520 are configured of the modified open / close ring oscillator-based time-digital converter 300 of FIG. 3. Since the configuration and operation of the modified open / close ring oscillator based time-digital converter 300 have been described in detail with reference to FIGS. 1 to 4, here, the first time-digital converter 510 and the second time-digital converter are described. A detailed description of the configuration and operation of the converter 520 will be omitted. Hereinafter, the output signal Y of the time-digital converter 500 capable of secondary noise shaping may be a signal in which a quantization error is a secondary noise shaped signal. It explains in detail.

As described above in relation to Figures 1 and 2, the first time - of the output signal (Y ₂₎ of the digital converter (520) output signal (Y ₁₎ and the second time-digital converter (510) The z-converted form is represented by Equations 4 and 5 below, respectively.

&Quot; (4) "

Y ₁ (z) = X (z)-(1-z ^-1 ) E ₁ (z)

[Equation 5]

Y ₂ (z) = AE ₁ (z)-(1-z ^-1 ) E ₂ (z)

Here, Y ₁ (z) and Y ₂ (z) are output signals Y ₁ of the first time-digital converter 510 and output signals Y of the second time-digital converter 520, respectively. ₂ ), X (z) represents a time interval to be measured, and E ₁ (z) and E ₂ (z) are quantization errors and the second time of the first time-digital converter 510, respectively. A quantization error of the digital converter 520 is shown.

The output signal Y of the signal converter 530 is expressed by Equation 6 below.

&Quot; (6) "

Y (z) = Y ₁ (z) + ((1-z ^-1 ) / A) Y ₂ (z)

When the above Equations 4 to 6 are combined, the output signal Y of the signal converter 530 is expressed as Equation 7 below.

[Equation 7]

Y (z) = Y ₁ (z) + ((1-z ^-1 ) / A) Y ₂ (z)

= X (z)-(1-z ^-1 ) E ₁ (z) + (1-z ^-1 ) E ₁ (z)-((1-z ^-1 ) ² / A) E ₂ (z)

= X (z)-((1-z ^-1 ) ² / A) E ₂ (z)

It can be seen from Equation 7 that the time-to-digital converter 500 capable of secondary noise shaping of FIG. 5 has a noise conversion function as shown in Equation 8 below.

[Equation 8]

N _TF (z) = (1-z ^-1 ) ² / A

Accordingly, as shown in Equation 8, the time-digital converter 500 capable of shaping the secondary noise of FIG. 5 may provide the output signal Y having the quantization error.

In FIG. 5, a case in which the second time-digital converter 520 is configured as the modified open / close ring oscillator-based time-digital converter 300 of FIG. 3 is described. The same effect can be obtained by the same operation even if the conventional switching ring oscillator-based time-to-digital converter (100).

6 is a block diagram illustrating a time-to-digital converter capable of shaping N (N is a positive integer of 3 or more) according to an embodiment of the present invention. As illustrated in FIG. 6, the time-digital converter 600 capable of N-order noise shaping is an extension of the time-digital converter 500 capable of second-order noise shaping to enable N-order noise shaping.

Referring to FIG. 6, the time-digital converter 600 capable of N-th order noise shaping includes N time-digital converters 610 and a first signal including a first time-digital converter to an Nth time-digital converter. And (N-1) signal conversion units 620 including the conversion unit to the (N-1) th signal conversion unit.

Each of the N time-digital converters 610 is a digital output signal Y _x that digitizes a time interval between the two input signals START and STOP in response to two input signals START and STOP ( x is a positive integer equal to or less than N) and the time interval corresponding to the quantization error by the digitization is amplified by A times to generate two output signals START_d and STOP_d having the amplified time interval between rising edges. . The two output signals START_d and STOP_d of the a-th (a is a positive integer less than (N-1)) are respectively input to the two inputs of the (a + 1) -time-digital converter. It is connected to be a signal (START, STOP).

Each of the (N-1) signal conversion units 620 generates one converted signal in response to the first signal conversion input signal and the second signal conversion input signal. The (N-1) th signal converter receives the digital output signal Y _{N of} the Nth time-digital converter as the first signal conversion input signal, and the (N-1) th time-digital converter Receives a digital output signal (Y _N-1 ) as the second signal conversion input signal to generate a (N-1) th conversion signal (I _N-1 ), wherein k (k is less than (N-2) Positive integer), and the signal converter receives the output signal of the (k + 1) th signal converter as the first signal conversion input signal and receives the digital output signal Y _{k of} the kth time-digital converter. Received as a signal conversion input signal to generate a _k- th conversion signal (I _k ). The first converted signal I ₁ becomes the final output signal Y of the time-digital converter 600 capable of N-th order noise shaping.

Each of the N time-digital converters 610 is composed of the modified open / close ring oscillator-based time-digital converter 300 of FIG. 3, and each of the (N-1) signal converters 620 is shown in FIG. 5. Is composed of a signal converter 530. 1 to 5, the configuration and operation of each of the N time-digital converters 610 and each of the (N-1) signal converters 620 have been described in detail. A detailed description thereof will be omitted, and the output signal Y of the time-digital converter 600 capable of N-th order noise shaping will be described in detail as a quantization error signal.

The output signals Y ₁ to Y _N of each of the N time-digital converters 610 are expressed by Equation 9 below.

[Equation 9]

Y ₁ (z) = X (z)-(1-z ^-1 ) E ₁ (z)

Y ₂ (z) = AE ₁ (z)-(1-z ^-1 ) E ₂ (z)

......

Y _N-1 (z) = AE _N-2 (z)-(1-z ^-1 ) E _N-1 (z)

Y _N (z) = AE _N-1 (z)-(1-z ^-1 ) E _N (z)

The (N-1) th signal converter receives the digital output signal Y _{N of} the Nth time-digital converter as the first signal conversion input signal, and the (N-1) th time-digital converter Since the digital output signal Y _N-1 is received as the second signal conversion input signal, the output signal I _{N-1 of} the (N-1) signal conversion unit is represented by Equation 10 below. .

[Equation 10]

I _N-1 (z) = Y _N-1 (z) + ((1-z ^-1 ) / A) Y _N (z)

When the equations for Y _N-1 (z) and Y _N (z) of Equation 9 are combined with Equation 10, the output signal I _{N-1 of} the (N-1) signal conversion unit ) Is expressed as in Equation 11 below.

[Equation 11]

I _N-1 (z) = Y _N-1 (z) + ((1-z ^-1 ) / A) Y _N (z)

= AE _N-2 (z)-(1-z ^-1 ) E _N-1 (z) + (1-z ^-1 ) E _N-1 (z)-((1-z ^-1 ) ² / A ) E _N (z)

= AE _N-2 (z)-((1-z ^-1 ) ² / A) E _N (z)

Applying for the above process in the first (N-2) signal conversion section output signal (I _N-2) to the first signal conversion unit output signal (I ₁₎ The result is a formula 12 below, It is expressed as

[Equation 12]

I _N-2 (z) = AE _N-3 (z)-((1-z ^-1 ) ³ / A ² ) E _N (z)

......

I ₁ (z) = X (z)-((1-z ^-1 ) ^N / A ^N-1 ) E _N (z)

Since the first converted signal I ₁ becomes the final output signal Y of the time-digital converter 600 capable of N-order noise shaping, the time at which the N-order noise shaping of FIG. 6 is possible from Equation 12. It can be seen that the digital converter 600 has a noise conversion function as shown in Equation 13 below.

[Equation 13]

N _TF (z) = (1-z ^-1 ) ^N / A ^N-1

Accordingly, as shown in Equation 13, the time-digital converter 600 capable of N-order noise shaping of FIG. 6 may recognize that the quantization error provides an N-order noise shaped output signal Y. FIG.

In FIG. 6, the case where the N-time time-digital converter is composed of the modified open / close ring oscillator-based time-digital converter 300 of FIG. 3 is described. Even with the time-digital converter 100, the same effect can be obtained by the same operation.

7 is a flowchart illustrating a time-digital conversion method capable of secondary noise shaping according to an embodiment of the present invention.

Referring to FIG. 7, in the time-to-digital conversion method capable of secondary noise shaping, the second digital input signal is separated from the rising edge of the first digital input signal in response to a first digital input signal and the second digital input signal. Generating a first enable signal enabled during a time interval until a rising edge (S710), and generating a first oscillation signal in response to the first enable signal by using a first open / close ring oscillator (S720) ), Generating a first digital output signal corresponding to the number of rising edges of the first oscillation signal in response to the first oscillation signal (S730), and responding to the first enable signal and the first oscillation signal. When the time interval between rising edges amplifies the time interval from the last rising edge of the first oscillation signal to the falling edge of the first enable signal by A times Generating a first time interval output signal and a second time interval output signal to correspond to the interval (S740), the first time interval output signal in response to the first time interval output signal and the second time interval output signal Generating a second enable signal that is enabled during a time interval from a rising edge of the second time interval output signal to a rising edge of the second time interval output signal (S750), using a second open / close oscillator to the second enable signal; Generating a second oscillation signal in response (S760); generating a second digital output signal corresponding to the number of rising edges of the second oscillation signal in response to the second oscillation signal (S770); Generating a time delayed signal by one sampling period in response to the two digital output signals (S780), in response to the second digital output signal and the time delayed signal; Generating a subtracted output signal by subtracting the time delayed signal from the second digital output signal (S785), amplifying the subtracted output signal by 1 / A times to generate an amplified signal (S790); Summing the amplified signal and the first digital output signal to generate a second noise shaped signal (S795).

Since the time-digital conversion method capable of secondary noise shaping provides an output signal Y in which a quantization error is secondary noise shaped, as described above with reference to FIGS. 1 to 5, the detailed description is omitted herein. .

The high-order noise-shaping time-to-digital converter and the time-to-digital conversion method according to the embodiment of the present invention have lower in-band quantization noise power than the conventional ring-based oscillator-based time-to-digital converter capable of primary noise shaping. (in-band quantization noise power) can be obtained to increase the resolution of the time-to-digital converter, and to simplify the circuit design compared to the method of increasing the frequency of the ring oscillator, there is no feedback path As a result, stability problems do not occur, so they can be efficiently used in the digital industry.

As described above, the present invention has been described with reference to a preferred embodiment of the present invention, but those skilled in the art may vary the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be understood that modifications and changes can be made.

1 is a block diagram illustrating a conventional open / close ring oscillator based time-to-digital converter.

FIG. 2 is a simulation diagram of the conventional open / close ring oscillator based time-to-digital converter of FIG. 1.

3 is a block diagram illustrating a modified open / close ring oscillator based time-to-digital converter according to an embodiment of the present invention.

FIG. 4 is a simulation diagram of the modified open / close ring oscillator based time-to-digital converter of FIG. 3.

5 is a block diagram illustrating a time-to-digital converter capable of secondary noise shaping according to an embodiment of the present invention.

6 is a block diagram illustrating a time-to-digital converter capable of N-order noise shaping according to an embodiment of the present invention.

7 is a flowchart illustrating a time-digital conversion method capable of secondary noise shaping according to an embodiment of the present invention.

Claims (13)

Enabled for a time interval from the rising edge of the first digital input signal to the rising edge of the second digital input signal in response to the first digital input signal and the second digital input signal. An enable signal generator for generating a signal; A gated-ring oscillator for generating an oscillation signal in response to the enable signal; A counter for generating a digital output signal corresponding to the number of rising edges of the oscillation signal in response to the oscillation signal; And And a time amplifier for generating a first time interval output signal and a second time interval output signal having a time interval between rising edges in response to the enable signal and the oscillation signal. The method of claim 1, wherein the time amplifier, The time interval between the rising edges of the first time interval output signal and the second time interval output signal corresponds to a time interval that amplifies the time interval from the last rising edge of the oscillation signal to the falling edge of the enable signal. Time-to-digital converter, characterized in that. A first digital output signal obtained by digitizing a time interval between the first digital input signal and the second digital input signal in response to a first digital input signal and a second digital input signal, and a quantization error due to the digitization A first time-digital converter configured to amplify a time interval corresponding to and generate a first time interval output signal and a second time interval output signal having the amplified time interval between rising edges; A second digital output signal for digitizing a time interval between the first time interval output signal and the second time interval output signal in response to the first time interval output signal and the second time interval output signal; A time-digital converter; And And a signal converter configured to generate a second noise shaped converted signal in response to the second digital output signal and the first digital output signal. The method of claim 3, wherein the first time-digital converter, Generate a first enable signal that is enabled during a time interval from a rising edge of the first digital input signal to a rising edge of the second digital input signal in response to the first digital input signal and the second digital input signal. A first enable signal generator; A first open / close ring oscillator for generating a first oscillation signal in response to the first enable signal; A first counter for generating the first digital output signal corresponding to the number of rising edges of the first oscillation signal in response to the first oscillation signal; And A time amplifier generating the first time interval output signal and the second time interval output signal having a time interval between rising edges in response to the first enable signal and the first oscillation signal, The second time-digital converter, A second phosphor enabled during the time interval from the rising edge of the first time interval output signal to the rising edge of the second time interval output signal in response to the first time interval output signal and the second time interval output signal. A second enable signal generator for generating an enable signal; A second open / close ring oscillator for generating a second oscillation signal in response to the second enable signal; And And a second counter for generating the second digital output signal corresponding to the number of rising edges of the second oscillation signal in response to the second oscillation signal. The method of claim 4, wherein the time amplifier, The time interval between the rising edges of the first time interval output signal and the second time interval output signal amplifies the time interval from the last rising edge of the first oscillation signal to the falling edge of the first enable signal. Time-to-digital converter, characterized in that corresponding to the time interval. The method of claim 5, wherein the signal conversion unit, A time delay unit generating a time delayed signal by one sampling period in response to the second digital output signal; A first adder and subtractor for generating a subtracted output signal by subtracting the time delayed signal from the second digital output signal in response to the second digital output signal and the time delayed signal; A gain amplifier for amplifying the subtracted output signal to produce an amplified signal; And And a second adder / subtractor for summing the amplified signal and the first digital output signal to produce the secondary noise shaped converted signal. 7. The time-digital converter of claim 6, wherein the amplification gain of the gain amplifier is an inverse of the amplification gain of the time amplifier. A digital output signal obtained by digitizing a time interval between the first digital input signal and the second digital input signal in response to a first digital input signal and a second digital input signal, respectively, and a time interval corresponding to the quantization error caused by the digitization. A first time-digital converter to Nth (N is a positive integer greater than or equal to 3) to amplify a to generate a first time interval output signal and a second time interval output signal having the amplified time interval between rising edges. N time-digital converters composed of time-digital converters (The N time-digital converters may include the first a (a is a positive integer less than (N-1)). The first time interval output signal and the second time interval output signal of the time-digital converter are respectively. Coupled to be the first digital input signal and the second digital input signal of the (a + 1) time-to-digital converter; And (N-1) signal converting units each comprising a first signal converting unit to a (N-1) th signal converting unit generating one converted signal in response to the first signal converting input signal and the second signal converting input signal, respectively (The (N-1) th signal converter receives the digital output signal of the Nth time-digital converter as the first signal conversion input signal and the digital output signal of the (N-1) th time-digital converter. Receives the second signal conversion input signal to generate a (N-1) th conversion signal, The k-th (k is a positive integer less than (N-2)) signal conversion unit receives the output signal of the (k + 1) signal conversion unit as the first signal conversion input signal and the k-th time-digital conversion And receiving a negative digital output signal as the second signal conversion input signal to generate a k-th conversion signal. The method of claim 8, wherein each of the N time-digital converters, An enable signal being generated in response to the first digital input signal and the second digital input signal to generate an enable signal that is enabled during a time interval from the rising edge of the first digital input signal to the rising edge of the second digital input signal. An enable signal generator; An open / close ring oscillator for generating an oscillation signal in response to the enable signal; A counter for generating the digital output signal corresponding to the number of rising edges of the oscillation signal in response to the oscillation signal; And A time amplifier for generating said first time interval output signal and said second time interval output signal having a time interval between rising edges in response to said enable signal and said oscillation signal; converter. The method of claim 9, wherein the time amplifier, The time interval between the rising edges of the first time interval output signal and the second time interval output signal corresponds to a time interval that amplifies the time interval from the last rising edge of the oscillation signal to the falling edge of the enable signal. Time-to-digital converter, characterized in that. The method of claim 10, wherein each of the (N-1) signal conversion unit, A time delay unit generating a time delayed signal by one sampling period in response to the first signal conversion input signal; A first adder and subtractor for generating a subtracted output signal by subtracting the time delayed signal from the first signal conversion input signal in response to the first signal conversion input signal and the time delayed signal; A gain amplifier for amplifying the subtracted output signal to provide an amplified signal; And And a second adder / subtractor for adding the amplified signal and the second signal conversion input signal to provide the converted signal. 12. The amplification gains of the respective gain amplifiers are equal to each other, the amplification gains of the respective time amplifiers are equal to each other, and the amplification gains of the respective gain amplifiers are equal to the amplification gains of the respective time amplifiers. Time-to-digital converter, characterized in that the inverse. Generating a first enable signal that is enabled during a time interval from the rising edge of the first digital input signal to the rising edge of the second digital input signal in response to the first digital input signal and the second digital input signal. step; Generating a first oscillation signal in response to the first enable signal using a first open / close ring oscillator; Generating a first digital output signal corresponding to the number of rising edges of the first oscillation signal in response to the first oscillation signal; The time interval between rising edges in response to the first enable signal and the first oscillation signal amplifies the time interval from the last rising edge of the first oscillation signal to the falling edge of the first enable signal by a factor of A. Generating a first time interval output signal and a second time interval output signal to correspond to one time interval; A second phosphor enabled during the time interval from the rising edge of the first time interval output signal to the rising edge of the second time interval output signal in response to the first time interval output signal and the second time interval output signal. Generating an enable signal; Generating a second oscillation signal in response to the second enable signal using a second open / close ring oscillator; Generating a second digital output signal corresponding to the number of rising edges of the second oscillation signal in response to the second oscillation signal; Generating a signal delayed by one sampling period in response to the second digital output signal; Generating a subtracted output signal by subtracting the time delayed signal from the second digital output signal in response to the second digital output signal and the time delayed signal; Amplifying the subtracted output signal by 1 / A to generate an amplified signal; And Summing the amplified signal and the first digital output signal to produce a second noise shaped signal.

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