The EuMC 2010 Conference was one of the 4 conferences held during the 13th European Microwave Week (EuMW2010): "Connecting the World", Paris, France, 26 September-1 October 2010A compact 6-bit phase shifter with high power-handling capacity is designed based on the use of metamaterial, composite right/left-handed transmission line (CRLH-TL). Eight PIN diodes mounted on the fingers of the CRLH-TL are used as switches to control the phase incursion of the input signal. Different phase shifts are achieved by using different states of the switches (PIN diodes) determined by 6 controlling bits. Since the surface current flowing through each of the switches is only a fraction of the total current through the device, the power handled by each of the PIN diodes is much smaller than the total power through the device; thus the power-handling capacity of the phase shifter can be greatly improved. The phase shifter is designed to provide a phase-shift range from 0° to 360° at a step of 5.625° and operate in the frequency band from 9.2 to 9.8 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has a much higher power-handling capacity than that of the PIN diode and low insertion losses across the operating frequency band. © 2010 EuMA.published_or_final_versionThe 40th European Microwave Conference (EuMC 2010), Pairs, France, 28-30 September 2010. In Proceedings of EuMC 2010, 2010, p. 437-44

Cheung, SW

Yuk, TI

Zhang, J

Microwave and Optical Technology Letters

A miniaturized 3-bit phase shifter with high power-handling capacity is designed based on the use of a single composite right/left-handed transmission line (CRLH-TL) unit cell. PIN diodes mounted on the fingers of the CRLH-TL unit cell are used as switches to control the phase shift of the input signal. Different phase shifts are achieved by using different states of the switches determined by the 3 controlling bits of the phase shifter. The surface current flowing through each of the switches is only a fraction of the total current through the device, so the power handled by each of the PIN diodes is much smaller than the total power through the device. The phase shifter is designed to provide a phase-shift range from 0° to 157.5° at a step 22.5° and operate in the frequency band from 9 to 10 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has much higher power-handling capacities than that of the PIN diode and low insertion losses across the operating frequency band. © 2010 Wiley Periodicals.link_to_subscribed_fulltex

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A 3-bit phase shifter with high-power capacity based on composite right/left-handed transmission line

A compact 6-bit phase shifter with high power-handling capacity is designed based on the use of metamaterial, composite right/left-handed transmission line (CRLH-TL). Eight PIN diodes mounted on the fingers of the CRLH-TL are used as switches to control the phase incursion of the input signal. Different phase shifts are achieved by using different states of the switches (PIN diodes) determined by 6 controlling bits. Since the surface current flowing through each of the switches is only a fraction of the total current through the device, the power handled by each of the PIN diodes is much smaller than the total power through the device; thus the power-handling capacity of the phase shifter can be greatly improved. The phase shifter is designed to provide a phase-shift range from 0° to 360° at a step of 5.625° and operate in the frequency band from 9.2 to 9.8 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has a much higher power-handling capacity than that of the PIN diode and low insertion losses across the operating frequency band. © 2010 EuMA.published_or_final_versio

Title A compact 6-bit phase shifter with high-power capacity based oncomposite right/left-handed transmission lineAuthor(s) Zhang, J; Cheung, SW; Yuk, TICitationThe 40th European Microwave Conference (EuMC 2010), Pairs,France, 28-30 September 2010. In Proceedings of EuMC 2010,2010, p. 437-440Issued Date 2010URL http://hdl.handle.net/10722/140270Rights Creative Commons: Attribution 3.0 Hong Kong LicenseA Compact 6-bit Phase Shifter with High-Power Capacity Based on Composite Right/Left-Handed Transmission Line  J. Zhang, S.W. Cheung and T.I. Yuk Department of Electrical and Electronic Engineering, The University of Hong Kong  Pokfulam Road, Hong Kong, China zhangjun@eee.hku.hk     Abstract— A compact 6-bit phase shifter with high power-handling capacity is designed based on the use of metamaterial, composite right/left-handed transmission line (CRLH-TL). Eight PIN diodes mounted on the fingers of the CRLH-TL are used as switches to control the phase incursion of the input signal. Different phase shifts are achieved by using different states of the switches (PIN diodes) determined by 6 controlling bits. Since the surface current flowing through each of the switches is only a fraction of the total current through the device, the power handled by each of the PIN diodes is much smaller than the total power through the device; thus the power-handling capacity of the phase shifter can be greatly improved. The phase shifter is designed to provide a phase-shift range from 00 to 3600 at a step of 5.6250 and operate in the frequency band from 9.2 to 9.8 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has a much higher power-handling capacity than that of the PIN diode and low insertion losses across the operating frequency band.  Index terms— Microwave Phase Shifter, Composite Right/Left-Handed Transmission Line (CRLH-TL), High Power-Handling Capacity I. INTRODUCTION Power-handling capacity, insertion loss and size are major concerns in the design of phase shifters. Phase shifters can be classified as passive and active types. Passive phase shifters can be implemented using the ferrite technology [1] to achieve higher power-handling capacities, but they are large and heavy. Active phase shifters can be implemented using solid-state devices such as FET and CMOS technologies to reduce the sizes. However, their low power-handling capacities and nonreciprocal characteristics limit their applications. In digital phase shifters, phase shift is usually obtained by switching between two transmission lines of different lengths or between lumped-element low-pass and high-pass filters [2]. Normally, the switches used are implemented using solid-state devices such as PIN diodes which typically have power-handling capacities of just a few Watts. Thus the power-handling capacities of the phase shifters are limited by the power-handling capacities of the switches. To construct an n-bit phase shifter, phase shifters providing different phase shifts can be cascaded together to provide the required phase shifts. This undoubtedly increases the physical size and insertion loss of the design. In this paper, the design of a 6-bit phase shifter based on the use of the metamaterial, composite right/left-handed transmission line (CRLH-TL) [3] is presented. The major advantages of the design are compact size, high power-handling capacity and low insertion loss. Eight PIN diodes mounted on the fingers of the CRLH-TL unit cell are used as switches to control the phase incursion of the input signal going through the device. Different phase shifts are achieved by using different states of the switches and 6 controlling bits are used to select one of the sixty-four states for the required phase shift. Since the surface current flowing through each finger (and the switch mounted on it) is only a fraction of the total current flowing through the phase shifter, the proposed phase shifter can handle a much higher power than a single PIN diode. The proposed 6-bit phase shifter is designed to have a phase-shift range from 00 up to 3600 at a step size of 5.6250 and operating frequency range from 9.2 to 9.8 GHz. Computer simulation and experimental measurements are used to study the performance of the phase shifter and both results show good agreements and performances. A chassis has been used to enclose the phase shift to form a phase-shifter module which has a small size of only 60 mm×40 mm×2mm. II. THEORY A. Model of CRLH-TL unit cell   via to groundouter fingerinner fingersouter fingerPort2Port1Wl’ via to groundCL 2LL CR/2LRCR/2 2LY1 Y2Y3(a) (b)  Fig. 1 (a) Schematic and (b) equivalent π-model of CRLH-TL unit cell 28-30 September 2010, Paris, FranceProceedings of the 40th European Microwave Conference978-2-87487-016-3 © 2010 EuMA 437The general schematic and equivalent π-model of a CRLH-TL unit cell are shown in Fig. 1, where LR is the right-handed (RH) series inductance, CR is the RH shunt capacitance, LL is the left-handed (LH) shunt inductance and CL is the LH series capacitance. The expressions for LR, CR, LL and CL are, respectively, given by [4,5]  00,re reR RZL l C lc Z cε ε= =                        (1)  ( )0.450.512( 1) 4.409 3 tanh 0.559.92 tanh 0.52 10L rhC l NWhWε−⎧ ⎡ ⎤⎪ ⎛ ⎞= + − ⎢ ⎥⎨ ⎜ ⎟⎝ ⎠⎢ ⎥⎪ ⎣ ⎦⎩⎫⎡ ⎤⎪⎛ ⎞+ ×⎢ ⎥⎬⎜ ⎟⎝ ⎠⎢ ⎥⎪⎣ ⎦⎭     (2)  and 2 22 2003ln ( )2 2Lreh r hL h r r hrZlcμπε⎡ ⎤⎛ ⎞+ +⎢ ⎥⎜ ⎟= ⋅ + − +⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦′+  (3)  where h is the thickness of the substrate, r is the radius of the ground pin, εr is the relative dielectric constant, εre is effective dielectric constant, l’ is the distance from the ground hole to the port, l is the length of the finger, N is the number of the fingers, W is the width of all the fingers and Z0 is the characteristic impedance of the fingers. The phase constant β of the CRLH-TL unit cell can be expressed as [3]:  1R RL LL CL Cβ ωω= −   (4)  An electromagnetic wave traveling through the CRLH-TL unit cell will have a phase incursion:  Lθ β= ×        (5)  where L is the length of the CRLH-TL unit cell. From (1)–(3), it can be seen that the structural parameters of the CRLH-TL unit cell determine the values of LR, CR, LL and CL which in turn determine the phase incursion through (4) and (5).  B. Phase Shifter based on CRLH-TL  To illustrate the principle of the proposed phase shifter, we use a single CRLH-TL unit cell with four switches (diodes) mounted on the fingers as shown in Fig. 2. The “closed” or “open” state in each of the switches will determine the values LR, CR, LL and CL through (1)-(3) and, in turn, the phase incursion θ in (5), thus each switch state can be used to provide a particular phase shift:  0( )m m Lθ β βΔ = − ×      (6)  where m is the index (from 0 to 2n-1) for switch state, βm is the phase constant in the mth-switch state and β0 is the phase constant in the zeroth-switch state. For convenience and without lost of generality, the zeroth-switch state can be taken as the state when all switches are close. With the use of four switches, there are sixteen possible switch states (from 0 to 15) determined by “closed” or “open” state in each of the four switches and controlled by using 4 controlling bits to have sixteen phase shifts.  Port--switches--via to groundPort Fig. 2 CRLH-TL unit cell mounted with four switches for 16 phase shifts   The simulation tool IE3D has been used to design the dimensions of a CRLH-TL unit cell with eight fingers, as shown in Fig. 2, with finger width and spacing between them of 0.1 mm, input and output impedance of 50 Ω and the criteria of |S11| < -15 dB and |S21| >-0.5 dB at 9.5 GHz. The substrate used in the design had a thickness of 0.28 mm and permittivity of 2.55. Results have shown that the required widths for the input and output ports were 0.78 mm and the lengths for the inner fingers and outer fingers were 3.5 mm  and 2.5 mm, respectively.   switchswitchswitch switch 0.1 mm0.78 mmport1 port2switch switchswitch switch 0.1 mm 0.78 mmport1 port2(a) (b) (c) Fig. 3 Simulated surface-current density distribution on CRLH-TL unit cell   (a) all switches “opened” (b) all switches “closed” (c) color scale of surface-current density  Surface-current density distribution has been used to study the power handled by the switches (PIN diodes) in the CRLH-TL unit cell. Figures 3(a) and 3(b) show the simulated surface-current density distributions with all four switches “opened” or “closed”, respectively, at 9.5 GHz. The arrowheads indicate the positions of the switches on the fingers of the CRLH-TL unit cell. With all switches “opened”, 438Fig. 3(a) shows that the largest surface-current density through the switches is about 1/25.1 (-28 dB) of that through the ports. While with all switches “closed”, Fig. 3(b) shows that the largest surface-current density through the switches is about 1/6.3 (-16 dB) of that through the ports. Since the width of the finger is 0.1 mm, only 1/7.8 of the width for the input and output ports, the largest surface-current through the switches is 1/49 of that through the ports. Thus the power-handling capacity of the phase shifter is about 49 times higher than the power-handling capacity of the switches (PIN diodes).  III.   DESIGN OF 6-BIT PHASE SHIFTER   switch for 450  switch for 22.50 switch for 11. 250  switch for 5.6250  switches for 900 switches for 1800 (a) (b)  Fig. 4 Design of 6-bit phase shifter with two CRLH-TL unit cells (a) the first CRLH-TL unit cell (b) the second CRLH-TL unit cell  Our design for a 6-bit phase shifter based on the use of the matematerial, CRLH-TL, is shown in Fig. 4. As can be seen from (1) - (6), the structural parameters of the CRLH-TL unit cell can be selected to provide the required phase shift. In Fig. 4(a), four switches are used to achieve sixteen different switch states and sixteen different phase shifts (including 00). The two switches on the inner fingers are used to provide the phase shifts of 5.6250 and 11.250, while the two switches on the outer fingers are used to provide the phase shift of 22.50 and 450. The positions of the switches on the fingers affect the phase shift.  In Fig. 4(a), the positions of the four switches producing the four corresponding phase shifts were obtained one-by-one through computer simulation. In the simulation, when the position of an open switch was being determined, all other switches were closed. When all positions had been determined, different switch states were then used to provide the other eleven phase shifts. There were interactions between switches, i.e., the total phase shift caused by two switches might not be exactly the same as the sum of the phase shifts caused by the two switches, but simulation has shown that this interaction was insignificant. Moreover, the interaction was minimised by manual tuning the positions of the switches. In Fig. 4(b), the two pairs of switches are used to produce the larger phase shifts of 900 or 1800. The pair of switches on the inner fingers is used to produce a phase shift of 900, while the pair of switches on the outer fingers is used to achieve a phase shift of 1800. The phase shift of 2700 is realized by “opening” all the four switches. The positions of the switches were determined as described previously.  1st bit2nd bit 3rd bit 4th bit 5th bit 5th bit 6th bit 6th bitRFin RFout---RF ---DC ---Via to Ground ---R ---L ---C ---Pin Diode Fig. 5 Layout of 6-bit phase-shifter module  By cascading the designs of the two CRLH-TL unit cells in Figs. 4(a) and 4(b), we can have a design for a phase shifter with a phase-shift range from 00 to 3600 at a step of 5.6250. The layout of such 6-bit phase shifter is shown in Fig. 5. It consists of two CRLH-TL unit cells, one realizing the phase shifts from 5.6250 up to 84.3750 and the other one realizing the phase shifts from 900 up to 2700. Any phase shifts at multiple numbers of 5.6250 can be achieved by using the 6 controlling bits according to (6).  IV. SIMULATION AND MEASUREMENT RESULTS   Fig. 6 Photograph of 6-bit phase-shifter module  The 6-bit phase shifter in Fig. 5 has been designed as described previously to operate in an operating frequency band of 9.2-9.8 GHz and fabricated using a polytetrafluoroethylen (PTFE) substrate with thickness of 0.28 mm and permittivity of 2.55. The photograph of the fabricated 6-bit phase-shifter module, as shown in Fig. 6, has a dimension of 60 mm×40 mm×2 mm. The PIN diodes used are from SKYWORKS Co. Ltd and have a dimension of 0.35 mm×0.35 mm×0.15 mm, operating frequency range of 100 439MHz-18 GHz and instantaneous power-handling capacity of 2.5W (34 dBm). Surface-mount-technology components such as resistors, capacitors and inductors are used to construct the bias circuits for the PIN diodes and also the circuits to isolate the RF signal from DC.   9.2 9.5 9.80102030405060708090100110120130140150160170180Phase shifts (Degree)Frequecny (GHz) Simulated results  Measured results Fig. 7 Simulated and measured phase shifts of 5.6250, 11.250, 22.50 450, 900 and 1800 9.2 9.5 9.8-50-40-30-20-100 Simulated |S11|of 5.6250    Measured |S11| of 5.6250 Simulated |S11| of 11.250  Measured |S11| of 11.250 Simulated |S11| of 22.50     Measured |S11| of 22.50  Simulated |S11|of 450            Measured |S11| of 450 Simulated |S11| of 900          Measured |S11| of 900 Simulated |S11| of 1800      Measured |S11| of 1800 Simulated and measured |S21|        of 5.6250, 11.250, 22.50, 450, 900, 1800S-parameters (dB)Frequency (GHz) Fig. 8 Simulated and measured |S11| and |S21| for phase shifts 5.6250, 11.250, 22.50 450, 900 and 1800  Computer simulation and measurements have been carried out to assess the phase shifts, phase errors, insertion loss and return loss of our proposed phase shifter. Results have shown that the phase shifter can provide a phase-shift ranges from 00 to 3600 at a step 5.6250, i.e., sixty-four phase shifts (including 00), in the frequency band from 9.2 to 9.8 GHz by using the sixty-four switch states. The phase shifts errors are within ±4% across the operating frequency band. The simulated and measured results on different phase shifts of 5.6250, 11.250, 22.50 450, 900 and 1800 across the frequency band from 9.2 to 9.8 GHz are shown in Fig. 7. To study the return loss and insertion loss, the S-parameters, |S11|and |S21|, of the phase shifter for different phase shifts across the frequency band from 9.2 to 9.8 GHz have been simulated and measured. Both simulated and measured results show good agreements. The measurement results have shown that the insertion loss is less than 1.3 dB (i.e., |S21| > -1.3 dB) and the return loss is more than 15 dB (|S11|< -15 dB) across the whole frequency band studied. The simulated and measured results on |S11| and |S21| for phase shifts of 5.6250, 11.250, 22.50 450, 900 and 1800 are shown in Fig. 8.  The power-handling capacity of the phase shifter has also been measured. In the measurement, the maximum transmitted peak power which caused a PIN diode to blow up was taken as the power-handling capacity of the phase shifter. The PIN diodes used in our design had an instantaneous power-handling capacity of 34 dBm. By analysing the surface-current density distribution of the two CRLH-TL unit cells in Fig. 4 at 9.5 GHz, the expected power-handling capacity of our proposed phase shifter was about 50.2 dBm, i.e. 42 times of the PIN diodes. The measured results have shown that our proposed phase shifter has a power-handling capacity of over 50.5 dBm in the frequency range studied, which is about 45 times of the power-handling capacity of the PIN diodes. V. CONCLUSIONS The design of a 6-bit phase shifter based on the use of metamaterial, CRLH-TL, has been presented. The phase shifter has a compact size and high power-handling capacity. It can provide a phase-shift range from 00 to 3600 at a step 5.6250 and operate in the frequency band from 9.2 to 9.8 GHz. Measurement results have shown that the phase shifter has a low insertion loss of less than 1.3 dB, a high return loss of more than 15 dB and a small phase shift error of ±4% across the operating frequency band. The power level that it can handle is 45 times higher than that of the PIN diodes used as switches in our design. REFERENCES [1] J. D. Adam, L. E. Davis, G. F. Dionne, E.F. Schloemann and S.N. Stitzer, “Ferrite Devices and Materials,” IEEE Transactions on Microwave Theory and Techniques, vol. 50, pp. 721-737, 2002. [2] S. Keul and B. Bhat, Microwave and Millimeter Wave Phase Shifters, MA: Artech house, 1991. [3] A. Lai, T. Itoh and C. Caloz, “Composite Right/Left-Handed Transmission Line Metamaterials,” IEEE Microwave Magazine, vol. 5, pp. 34-50, 2004.  [4] Inder Bahl, Lumped Elements for RF and Microwave Circuits, Boston& London: Artech House, 2001. [5] E. G. Marc and A. P. Robert, “Modelling Via Hole Grounds in Microstrip,” IEEE Microwave and Guided Wave Letters, vol. 1, pp. 135-137, 1991. 440

A compact 6-bit phase shifter with high-power capacity based on composite right/left-handed transmission line

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A compact 6-bit phase shifter with high-power capacity based on composite right/left-handed transmission line

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