Design of Miniaturized Synthetic Quasi-TEM Transmission-Line-Based CMOS Active Filter
Date Issued
2011
Date
2011
Author(s)
Lee, Meng-Lin
Abstract
This dissertation presents a design of high miniaturized third-order transmission- line-based (TL-based) active bandpass filter (BPF), which is fabricated using standard 0.18-μm complementary metal-oxide-semiconductor (CMOS) one-poly six-metal (1P6M) technology on a silicon substrate with a thickness of 480 μm and designed at the central frequency of 1.58 GHz in a chip area of 0.58% λ0 × 0.44% λ0, λ0 is the free-space wavelength at the central frequency. In this dissertation, the RF BPFs, which are fabricated in semiconductor technologies and presented in the published literature, are assessed against the degree of miniaturization and acceptability of performance. The statistics are summarized in a figure, which reveals that the CMOS TL-based active BPF herein has the lowest normalized area per resonator of active BPFs and the degree of miniaturization approaches the one of commercial FBAR devices. The new synthetic transmission line proposed in this dissertation has the widely flexibilities on the syntheses of guiding characteristics, like complementary-conducting-strip transmission line (CCS TL), and can further reduce the occupied chip area without compromising the transmission loss. Thus, such a synthetic transmission line enables the CMOS TL-based active BPF herein to be substantially miniaturized. Moreover, the frequency dependent negative conductance, which is produced from a modified nMOS cross-coupled pair, compensates for the frequency dependent loss in the TL-based resonator to enhance the quality factor (Q factor) of a composite parallel resonator. Therefore, the CMOS TL-based active BPF acquires adequate loss compensation to reduce the insertion loss with good passband flatness and the stability is also improved. Based on the techniques mentioned above, an CMOS third-order TL-based active BPF with low passband disturbance is designed in a chip area of 1099.47 μm × 837.48 μm or 0.58% λ0 × 0.44% λ0. The prototype consumes a current of 8.0 mA from 1.8 V and has 0.68-dB insertion loss at the central frequency of 1.58 GHz. The 3dB bandwidth is 8% with the return losses more than 16 dB. The passband ripple is 1.24 dB.
Additionally, the comprehensive design of wide upper stopband suppression for a packaged 1.53 GHz CMOS active bandpass BPF with on-chip electrostatic discharge (ESD) protection circuits is developed from the chip level to the package in the second part of this dissertation. So far, this is the first time that outband spurious responses are discussed and presented in the design of RF monolithic active BPF. In a composite parallel resonator, not only the signal at fundamental frequency but also the spurious ones at odd-harmonic frequencies are enhanced by the degenerate nMOS cross-coupled pair. The spurious responses are controlled and shifted towards higher frequencies by using the capacitively loaded TL resonator method in the COMS active BPF design to achieve wide upper stopband suppression. The fabricated chip of the aforesaid CMOS active BPF is packaged using the chip-on-board (COB) process in an area of 3.71 mm × 2.50 mm. In the lumped equivalent circuit analysis, the ground bondwires, which accompany the parasitic inductor at ground, in COB package influence the stopband suppression of the packaged CMOS active BPF and this parasitic effect is minimized in the package design. In addition, the influences of the variation in length per bondwire on the stopband suppression are also demonstrated. Measurement results indicate that the packaged CMOS active BPF has 0.95-dB insertion loss at a central frequency (f0) of 1.53 GHz with a 3dB bandwidth of 3.1%, while a current of 8 mA is consumed from 3.0 V. The stopband suppressions at 2f0 and 3f0 are 44.57 dB and 52.78 dB, respectively. Furthermore, the suppression exceeds 35 dB from 1.09f0 to 10.05f0. The ESD tests demonstrate that the two RF ports of the prototype have the Human-Body Model (HBM) ESD protection level of 500 V. Finally, in the temperature variation measurement, the central frequency of the prototype shifts from 1.587 to 1.479 GHz with a shift rate of -0.9 MHz/℃ from -40℃ to +80℃.
Subjects
金屬氧化物半導體, 主動帶通濾波器, 負阻抗, 假象訊號, 截止帶抑制
Type
thesis
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