WO2015037953A1

WO2015037953A1 - Highly integrated filter type phase shifter

Info

Publication number: WO2015037953A1
Application number: PCT/KR2014/008549
Authority: WO
Inventors: 박철순; 송인상; 오인열; 조성준; 김홍이; 이채준; 이해진; 이중호; 윤종현
Original assignee: 한국과학기술원
Priority date: 2013-09-16
Filing date: 2014-09-15
Publication date: 2015-03-19
Also published as: KR20150032370A; KR101548980B1

Abstract

The present invention relates to a phase shifter having a high-pass filter and a low-pass filter integrated altogether into a single chip and, more particularly, to a highly integrated filter type phase shifter in which a serial capacitor and a parallel inductor, which configure the high-pass filter, are arranged in an inner space between a serial inductor and a parallel capacitor, which configure the low-pass filter, thereby reducing chip size. In addition, the present invention relates to a phase shifter, which shifts the phase by selectively operating a high-pass filter and a low-pass filter, wherein each of the high-pass filter and the low-pass filter has at least one switching unit for selectively receiving an input signal, and the switching unit reduces an overall chip size by replacing a single pole double throw switch including a transistor, an inductor connected in parallel between a drain end and a source end of the transistor and a high resistor connected to a substrate of the transistor.

Description

Highly Integrated Filter Phase Shifters

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shifter, and more particularly, to a phase shifter having low loss characteristics and a degree of integration by integrating a high pass filter having a smaller size than that of the low pass filter in a space of a low pass filter having a considerable size in a millimeter wave band.

Recently, a variety of researches have been extensively carried out with high interest in millimeter wave and terahertz band high speed data communication. Millimeter-wave and terahertz communications require beamforming techniques because of the high loss due to high frequencies and the difficulty of signal generation. The beamforming technique uses an array antenna, and generates a beam in a desired direction by adjusting a phase of a signal excited by the antenna. The most important block in beamforming technology is the phase shifter that controls the phase of the signal. Phase shifter is a kind of circuit used for transmitting / receiving module. It is a key component for changing the phase of signal to phased array antenna. It is used for microwave antenna of satellite and satellite. The phase shifter adjusts the length of the electrical signal in an electrical or physical manner. Since phase control through physical methods is large and slow, they are not suitable for small, high-speed operation, and electrical methods are mainly used in the millimeter wave and terahertz bands.

The phase shifter can be implemented in various ways. In the case of a filter type phase shifter composed of a low pass filter and a high pass filter, a continuous phase shift cannot be generated as a single element, but it can have good phase shift characteristics in a relatively simple method. There is an advantage. In addition, since it is composed of passive elements, power consumption is low and good linearity has been widely used in an array antenna system of millimeter wave band, which is difficult to obtain performance due to high complexity. Due to the frequency characteristics of the filter structure, a phase of 90 Hz or more cannot be generated, and the band characteristic of the filter deteriorates as it approaches 90 Hz. Therefore, in general, a high-pass filter and a low-pass filter are combined to implement a filter type phase shifter. We then choose a method that optimizes the overall gain, band, and phase characteristics. The conventional method simply puts two filters in parallel and takes a selective mode of operation through a single pole double throw (SPDT) switch, and the size of the two SPDT switches themselves is not negligible. However, it is not suitable for integration on silicon.

1 is a conventional filter-type phase shifter, comprising a high pass filter composed of two capacitors and one inductor, and a low pass filter composed of two inductors and one capacitor, respectively, and an operation mode of the high pass filter and the low pass filter. Single pole double throw (SPDT) switches for selection are located on both sides.

The phase shifter of the filter type as shown in FIG. 1 has been widely used due to its simple operating principle and ease of implementation. However, in the conventional structure, as shown in FIG. 1 and Patent Document 1, two modes of a high pass filter and a low pass filter are separately configured, and they are selectively operated using two single pole double throw (SPDT) switches. There is a problem that the size becomes large enough not to be suitable for integration.

2 is a simulation result showing that the insertion loss characteristic of the ideal low pass filter deteriorates with increasing phase. The filter can change phase up to 90 ㅀ, and as the amount of phase change increases, the overall filter performance deteriorates. Simulation results show that the insertion loss characteristics of the ideal lowpass filter without loss are increased by 20 ㅀ and the band characteristics deteriorate as the insertion phase increases. Occurs.

Due to this problem, as shown in FIGS. 3 to 5, a single mode phase shifter to solve the size problem can be examined by adopting a structure in which a desired phase is changed to only one mode on silicon as shown in FIGS. 3 to 5. .

3 is a filter type phase shifter implemented only in a low pass filter mode. When the first transistor T1 is turned on and the second transistor T2 is turned off, as shown in FIG. 4, the inductor Ls and the capacitor Cp / 2 operate as a band stop filter and bypass the phase shifter. (bypass) It works. In addition, when the first transistor T1 is turned off and the second transistor T2 is turned on, as shown in FIG. 5, the inductor Ls and the two capacitors Cp form a low pass filter to generate a required phase shift. .

FIG. 4 is an equivalent circuit of the bypass mode of the phase shifter of FIG. 3, in which the inductor Ls and the capacitor Cp / 2 operate as a band erasing filter, and thus an applied signal is transmitted through the turned on first transistor T1. do. FIG. 5 is an equivalent circuit diagram of a phase shifter of the low pass filter type of FIG. 3. The phase change required by the inductor Ls and the two capacitors Cp occurs.

However, the single mode phase shifter as shown in Figs. 3 to 5 causes degradation of the overall performance by implementing all required phases in one mode, which is a more serious problem in high loss bands such as millimeter wave bands. . In addition, in the case of the filter type phase shifter, the phase shifter of the single mode must be solved because the phase shifter of 360 mode is realized by connecting several phases in series rather than operating as a single element. I think it's a task to do.

* Prior art literature

* Patent Literature

1. Korea Registered Patent No. 10-0652232 (registered November 23, 2006)

An object of the present invention is to provide a filter type phase shifter in which a high pass filter is integrated inside a low pass filter to improve low loss characteristics and integration as a phase shifter operating in a millimeter wave band to solve the above problems.

The integrated filter type phase shifter according to the present invention for solving the above problems is a phase shifter in which both a high pass filter and a low pass filter are integrated on one chip, and an internal space between a series inductor and a parallel capacitor constituting the low pass filter. The chip size is reduced by arranging a series capacitor and a parallel inductor constituting the high pass filter in a space.

In another embodiment of the present invention, a highly integrated filter type phase shifter is a phase shifter for shifting a phase by selectively operating a high pass filter and a low pass filter, wherein the high pass filter and the low pass filter selectively select an input signal. A switching unit is provided to receive the switching unit, wherein the switching unit includes a transistor, an inductor connected in parallel between the drain terminal and the source terminal of the transistor, and a high resistance connected to the substrate of the transistor.

As another embodiment of the present invention, the highly integrated filter type phase shifter includes an inductor array and a capacitor array of various sizes, and the inductor array and the capacitor array are connected to each other by a plurality of switching elements, and then combined with a high pass filter or a low pass. A filter is formed, and the plurality of switching elements selectively connect the inductor and the capacitor according to a control signal to operate the phase shifter as a high pass filter or a low pass filter.

The present invention has a high speed data communication characteristic when applied to a millimeter wave band mobile terminal by providing a small phase shifter having low power and low loss characteristics.

When the present invention is manufactured in a CMOS process, the reflection loss can be lowered to 10 dB or less at 55 GHz to 65 GHz, and the insertion loss is reduced to 3.8 dB and 4.4 dB in the low pass filter and the high pass filter mode, and has a phase shift characteristic of about 83 dB. Has

The present invention can solve the chip size by integrating the high pass filter inside the low pass filter, the size of the chip that must be increased to obtain the 90 kHz phase change characteristics.

According to the present invention, the insertion loss is increased by parasitic capacitance when the switch is turned off, and thus the insertion loss is reduced through the inductor and the high resistance connected in parallel with the transistor. Has characteristics.

1 is a filter type phase shifter of a general structure.

2 is a graph of simulation results showing degradation of insertion loss characteristics with increasing phase in an ideal filter.

3 is a filter type phase shifter implemented only in a low pass filter mode.

4 is an equivalent circuit diagram of a reference state of a filter type phase shifter implemented only in a low pass filter mode.

Fig. 5 is an equivalent circuit diagram of a low pass filter state of a filter type phase shifter implemented only in the low pass filter mode.

6 is a phase shifter according to the present invention.

7 is a switching device shown in FIG.

8 is a layout diagram of a phase shifter according to the present invention.

9 is a graph showing the reflection loss and insertion loss characteristics of the phase shifter according to the present invention.

10 is a phase adjustment performance graph of the phase shifter according to the present invention.

Hereinafter, specific embodiments for the practice of the present invention will be described with reference to the drawings. The illustrated drawings are only enlarged to the essential content for clarity of the invention, and the additional ones are omitted and should not be construed as limited to the drawings.

6 is a highly integrated filter type phase shifter according to the present invention, and includes inductor arrays Ls1 and Lp1 having various sizes and capacitor arrays Cs1, Cs2, Cp1 and Cp2, and the inductor array and the capacitor array have a plurality of switching. element to form a high-pass filter or low-pass filters each connected in combination with (S1 ~ S5), the switching device of said plurality is selectively connected to the inductor and capacitor filter high-frequency group the phase shift in response to a control signal (V _control) Or operate as a low pass filter. That is, the inductor with the low pass filter may overlap the inductor with the high pass filter, and the capacitor with the high pass filter may be used with the capacitor with the low pass filter, thereby realizing the high pass filter and the low pass filter in a small area. However, without forming each filter separately, the inductor or capacitor used in the low pass filter can be connected or disconnected by the switching element so that the filter can be used in the high pass filter. This can be more effective when a phase shifter array is used than one phase shifter.

The phase shifter may be implemented by a low pass filter, a high pass filter, a high pass filter switching unit (S1, S2), a low pass filter switching unit (S3, S4, S5), and a controller (INV).

In particular, the present invention is arranged between the series capacitors Cs1 and Cs2 and the parallel inductor Lp1 constituting the high pass filter between the series inductor Ls1 and the parallel capacitors Cp1 and Cp2 constituting the low pass filter. The invention can reduce the chip size by the size. Referring to FIG. 8, since the size of the inductor is overwhelmingly larger than that of the capacitor in the millimeter wave band, the phase shifter of the present invention uses the minimum number of inductors of the low pass filter and the high pass filter, and increases the capacitor having a small area instead. In this way, the chip size can be reduced even though the filter is of the same order. In particular, since the size of the inductor constituting the low pass filter is larger than that of the capacitor or the inductor or capacitor constituting the high pass filter, the low pass filter does not use two inductors and one capacitor. The implementation makes the size of the phase shifter small.

The low pass filter is a pi-type filter that passes only the low frequency components of the input signal and delays the phase of the signal. The low pass filter includes a series inductor Ls1 and two parallel capacitors Cp1 and Cp2. The low pass filter adds more inductors and capacitors as the order increases. As the order increases, the filtering becomes sharper, resulting in better pass characteristics, but worse insertion loss or group delay, and larger filter size. The low pass filter may be implemented as a low pass filter having different orders of two or more, including a capacitor and an inductor, as well as a third-order filter including one series inductor Ls1 and two parallel capacitors Cp1 and Cp2. .

The high pass filter is a tee (T) -type filter which passes only a high frequency component of an input signal and accelerates the phase of the signal, and includes two series capacitors Cs1 and Cs2 and one parallel inductor Lp1. As with the low pass filter, the high pass filter adds an additional number of inductors and capacitors. The high pass filter may be implemented as a third order filter including two series capacitors Cs1 and Cs2 and one parallel inductor Lp1, as well as a high pass filter having two or more orders of magnitude including a capacitor and an inductor. .

The switching elements constituting the high pass filter switching units S1 and S2 and the low pass filter switching units S3, S4, and S5 use a switching element having a structure as shown in FIG. use. 7, the switching elements are implemented in the third transistor (T3), an inductor (Lr) and a high resistance (R _body). In order to solve the problem that the parasitic capacitance of the third transistor T3 becomes very large when the third transistor T3 is in the off mode, the parasitic capacitance and the band erasure filter are operated to prevent signal leakage caused by the parasitic capacitance. The inductor Lr is connected in parallel with the drain and the source of the third transistor T3. When the third transistor T3 is in the on mode, since the inductor Lr has a sufficiently large value, the inductor Lr is connected in parallel with the third transistor T3 and thus, the operation of the third transistor T3 and The influence of the inductor Lr on the performance of the switching element is minimal. When the third transistor T3 is in the off mode, the parasitic capacitance of the third transistor T3 is canceled by the inductance of the inductor Lr, thereby reducing the loss of a signal.

When the third transistor T3 is implemented in a CMOS process, when the signal passes, the leakage of the signal occurs to the substrate body of the third transistor T3, so that the substrate of the third transistor T3 is prevented. The high resistance (R _body ) is inserted into the high resistance (R _body ) is formed inside the substrate to prevent leakage of the signal.

The high pass filter switching units S1 and S2 include a first switching element S1 for passing an input signal to the high pass filter and a second switching element S2 for transmitting the output signal of the high pass filter to the output pad. The operation of the first switching element S1 and the second switching element S2 is simultaneously performed by a control signal.

The low-pass filter switching units S3, S4, and S5 may include a fourth switching element for transmitting a signal passing through the third switching element S3 and the parallel capacitor Cp to pass the input signal to the low-pass filter to the ground line. S4) and the fifth switching element S5.

The low loss characteristics can be improved by connecting the switching elements shown in FIG. 7 to the individual capacitors Cp and grounding them more reliably. Therefore, when operating in the low pass filter mode of the conventional phase shifter, it is possible to solve the problem that the loss characteristic caused by the grounded structure by combining the common nodes of the two capacitors together.

The controller INV may be implemented as an inverter INV that inverts and outputs the control signal V _control . The input terminal of the inverter INV is connected to a terminal for controlling one of the high pass filter switching units S1 and S2 or the low pass filter switching units S3, S4, and S5, and the output terminal of the inverter INV is rested. Connect with one controlling terminal. Using the inverter, the high pass filter and low pass filter can be controlled by one signal (V _control ). For example, when the control signal V _control is logic high, the high pass filter switching units S1 and S2 are operated in the on mode, so that the output signal of which the phase of the input signal is advanced by the high pass filter can be obtained. When V _control ) is logic low, the low pass filter switching units S3, S4, and S5 operate in the on mode, and thus the low pass filter may obtain an output signal having a delayed phase of the input signal. When the high pass filter switching units S1 and S2 are turned on, a signal is inputted to the high pass filter and the output signal is output with the phase advanced from the phase of the input signal, and the low pass filter switching units S3, S4, and S5 are turned on. In this state, the input signal is transmitted to the low pass filter and the output signal is delayed in phase than the phase of the input signal. The phase change is realized as the difference between the advanced phase passing through the high pass filter and the delayed phase passing through the low pass filter.

8 is a layout diagram for manufacturing a phase shifter according to the present invention in a CMOS process. In the case of the phase shifter of the present invention, it is possible to implement a very small size of 0.47x0.36 mm ² including the pad. In the phase shifter shown in FIG. 8, the series inductor Ls1 is formed by rotating a transmission line a predetermined number of times between the input pad and the output pad, and the parallel capacitors Cp1 and Cp2 are connected to the series inductor ( It is arrange | positioned at the both ends of Ls1). A parallel inductor Lp1 and a series capacitor Cs1 and Cs2 having a smaller size than the series inductor Ls1 are disposed in a space between the series inductor Ls1 and the parallel capacitors Cp1 and Cp2. The high pass filter switching units S1 and S2 are disposed between the input pad and the series capacitor Cs1 and between the output pad and the series capacitor Cs2 and include an inductor connected in parallel to the transistor and the drain and the source of the transistor. In addition, the high pass filter switching units S1 and S2 include a high resistance connected to the substrate to prevent signal leakage of the transistor to the substrate. The low-pass filter switching unit S3 is disposed between an input pad and the series inductor Ls1, and is connected to the inductor connected in parallel with a transistor and a drain and a source of the transistor, and connected to the substrate for preventing signal leakage to the substrate of the transistor. High resistance disposed. In addition, the low-pass filter switching unit (S4, S5) is a transistor disposed between the parallel capacitor and the ground, an inductor connected in parallel to the drain and the source of the transistor, the connection arrangement to the substrate for preventing signal leakage to the substrate of the transistor Includes high resistance. By connecting the inductors Lm1 and Lm2 for regulating the impedance matching between the input pad and the switching element S3 and the output pad and the series inductor Ls1, respectively, the impedance is matched to reduce the transmission loss.

As in the conventional phase shift of FIG. 1, the size of one single pole double throw (SPDT) switch is about 0.5x0.5 mm ² , and when the two single pole double throw switches, the high pass filter and the low pass filter are separately configured, It can be seen that the phase shifter of the present invention greatly improves the degree of integration compared to the area becoming large enough to be inadequate to integrate.

9 is a view showing the reflection loss and insertion loss characteristics of the highly integrated filter type phase shifter according to the present invention. In addition to miniaturizing the size, the present invention satisfies both the reference 10dB from 55GHz to 65GHz and the insertion loss shows low loss characteristics of 3.8dB and 4.4dB in the high pass filter and the low pass filter mode.

Figure 10 shows the phase control characteristics of the high density millimeter wave band low loss phase shifter according to the present invention. The phase shifter designed as shown in FIG. 6 may acquire a 83 GHz phase shift characteristic in the 55 GHz to 65 GHz band.

The phase shifter having high integration and low loss characteristics of the present invention is necessary in millimeter wave and terahertz bands where loss characteristics are very important. When the phase shifter of the present invention is applied, the wireless communication system can expect an increase in data transmission efficiency. The present invention can be utilized for a beamforming system suitable for high-capacity high-speed data wireless transmission using a millimeter wave band.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

* Explanation of the sign

S1, S2, S3, S4, S5: switching element

Ls1: Series Inductor

Lp1: Parallel Inductor

Cs1, Cs2: series capacitor

Cp1, Cp2: Parallel Capacitors

Claims

In the phase shifter in which both the high pass filter and the low pass filter are integrated on one chip,

And a high pass filter comprising at least one series capacitor and a parallel inductor in a low pass filter including at least one series inductor and a parallel capacitor.
The method of claim 1,

The low pass filter,

Wherein the series inductor is one, and the parallel capacitor is connected in parallel to both ends of the series inductor.
The method of claim 1,

The series inductor is formed by rotating a predetermined number of transmission lines between an input pad and an output pad, and the parallel capacitor is connected to both ends of the series inductor, and a space between the series inductor and the parallel capacitor disposed at both sides. And the high pass filter is formed by integrating a series capacitor and a parallel inductor smaller in size than the series inductor.
The method of claim 1,

And a high pass filter switching unit including a transistor disposed between an input pad and the series capacitor and an inductor connected in parallel with a drain and a source of the transistor.
The method of claim 4, wherein

The high pass filter switching unit,

And a high resistance formed on one surface of the transistor substrate.
The method of claim 1,

And a low pass filter switching unit including a transistor disposed between an input pad and the series inductor and an inductor connected in parallel with a drain and a source of the transistor.
The method of claim 1,

The low pass filter switching unit,

And a low pass filter switching unit including a transistor disposed between the parallel capacitor and ground and an inductor connected in parallel with a drain and a source of the transistor.
The method according to claim 6 or 7,

The low pass filter switching unit,

And a high resistance connected to the substrate of the transistor.
The method of claim 8,

And an inductor formed between the input pad and the output pad to match impedance.
The method of claim 1,

And a controller for exclusively operating the high pass filter switching unit and the low pass filter switching unit according to a control signal.
The method of claim 10,

The controller,

An inverter for inverting and outputting the control signal,

An input terminal of the inverter is connected to a terminal for controlling one of the high pass filter switching unit or the low pass filter switching unit,

And an output terminal of the inverter is connected to a terminal for controlling the other one.
The method of claim 1,

The high pass filter,

2. A highly integrated filter type phase shifter characterized in that two series capacitors are connected in series and a parallel inductor is connected with a ground line at a contact node of the two series capacitors.
A phase shifter for shifting a phase by selectively operating a T-type high pass filter and a Pi type low pass filter, wherein the high pass filter and the low pass filter include at least one switching element for each filter to selectively receive an input signal. But

The switching device,

transistor;

An inductor connected in parallel between the drain terminal and the source terminal of the transistor;

And a high resistance coupled to the substrate of the transistor.