Browsing by Author "Niu, DC"

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A decade bandwidth resistive FET singly balanced MIC mixer
(1999)
Chang, CY
;
Yang, CC
;
Niu, DC
;
電信工程研究所
;
Institute of Communications Engineering
A novel decade bandwidth resistive FET singly balanced MIC mixer using a broadband CPW to CPS balun is developed. The mixer uses two NEC71000 MESFETs and realized with uniplanar lines. At 17 dBm LO power and 1 GHz IF, the mixer shows a conversion loss of 5.7 to 11 dB for 2 to 20 GHz RF and 10 to 15 dB for 20 to 27 GHz RF. The IF bandwidth is from 10 MHz to 7 GHz. The signal orthogonality between RE and IF makes the IF signal may overlap the RF signal. The mixer shows an output P-1dB of 11.5 dBm (corresponding to input P-1dB of 18.5 dBm) at 8 GHz RF, 1 GHz IF and 16.5 dBm LO power. The input IF, is 24 to 37 dBm corresponding to 2.5 to 20 GHz RF and 1 GHz IF. The mixer is fabricated on a 15 mil thick Al2O3 MIC substrate.
A multioctave bandwidth rat-race singly balanced mixer
(1999-01-01)
Chang, CY
;
Yang, CC
;
Niu, DC
;
傳播研究所
;
Institute of Communication Studies
In this letter, we describe a broad-band 7.5-46 GHz rat-race ring singly balanced mixer. The rat-race ring consists of an ideal crossover phase inverter and is designed to have a Chebyshev response of order two. The mixer diodes are virtually grounded via a quarter-wavelength low-impedance FCPW (finite ground plane CPW) open circuit stubs. The mixer shows more than 5 times RF bandwidth and de to 5 GHz LF bandwidth. The circuit is realized using FCPW on 25 mil Al2O3 substrate.
A novel CPW interdigital filter
(2001)
Chang, CY
;
Niu, DC
;
電信工程研究所
;
Institute of Communications Engineering
A novel interdigital filter using suspended substrate CPW is proposed in this paper. The design need not use EM simulator. Discussions of the higher order mode resonance of the resonator and the design procedures of this novel filter are provided. The effect of bonding wires, which is essential for this CPW filter, is also reviewed. Two prototype X-band filters are fabricated. The measured filter performances match well with the theory.
An X-band front-end module using HTS technique for a commercial dual mode radar
(2005-06-01)
Niu, DC
;
Huang, TW
;
Lee, HJ
;
Chang, CY
;
電信工程研究所
A front end module of receiver has been designed to eliminate the interference between the tracking and searching radar used in commercial radar application. The module is located at the receiving path of the searching radar. The proposed module includes two parts, the HTS superconducting filter and cryogenic low noise amplifier. The bandwidth of the eight-resonator HTS hairpin filter is 2% at the X-band frequency. Low insertion loss (below1 dB) and good skirt rejection (down to 60 dB at 50 MHz from the pass-band edge) are obtained. The two-stage low noise amplifier is designed by commercial low noise HEMT devices, NE321000. Two Lange couplers are located at output and input port of each amplifier stage to improve the return loss and to make LNA easily match to optimal low noise impendence. The cryogenic amplifier shows 30 dB gain and 0.4 dB NF at 77 K in X-band. A very high rejection is necessary for the elimination of unwanted spurious signals. The acceptable specification is 110 dB down at 500 MHz away from the band-edge of the filter. In general, the skirt rejection of a hairpin HT filter is pretty good near the pass-band edge, but may become worse far from the pass-band edge. To meet the requirement of this commercial radar application, a high rejection suspended stripline filter is put after the low noise amplifier. The whole module shows an maximal NF of 1.5 dB, a gain of 25 dB around pass-band frequencies, and a rejection of better than 110 dB at 500 MHz away from the band edge of the filter. It totally solves the interference problem in this dual mode radar.
Broadband, planar, doubly balanced star mixers
(2000)
Chang, CY
;
Tang, CW
;
Niu, DC
;
電信工程研究所
;
Institute of Communications Engineering
Planar broadband star mixers comprising two CPW-CPS T-junction dual baluns are developed. The bandwidth is about 6:1 without treatment of even mode resonance. After improving of even-mode resonance, the measured relative bandwidths of the star mixers can be larger than 15:1. The planar structure of the circuit is suitable for both MIC and MMIC fabrication. Some MIC prototype circuits are fabricated with Al2O3 substrate. The measured conversion losses of the star mixers are about 6 to 10 dB typically within the bandwidth.
Ultra-broad-band doubly balanced star mixers using planar Mouw's hybrid junction
(2001-06-01)
Chang, CY
;
Tang, CW
;
Niu, DC
;
電信工程研究所
;
Institute of Communications Engineering
Ultra-broad-band star mixers using planar Mouw's hybrid junction [1] are presented in this paper. The planar Mouw's hybrid junction is realized by coplanar waveguide (CPW) to coplanar strip (CPS) or CPW to CPW T-junctions. A new explanation of Mouw's theory based on coupled transmission lines and including the transmission line losses is presented, The modified theory is more suitable for ultra-broad-band mixer design. Some prototype mixers with CPW to CPS or CPW to CPW T-junctions are fabricated with Al2O3 substrate, The prototype mixers show a bandwidth of greater than 20:1 if the even-mode resonance has been damped out. Method for damping out the even-mode resonance is also presented. All of the prototype circuits show much broader bandwidth than that of conventional star mixer.