Title: 新型互補式金氧半類比二階高頻濾波器之設計與分析及其在高階濾波器之應用
The Design and Analysis of New CMOS Analog High-Frequency Biquadartic Filers and Their Applications in High-Order Filters
Authors: 許恆壽
Xu, Heng-Shou
吳重雨
Wu, Zhong-Yu
電子研究所
Keywords: 類比濾波器;高頻濾波器;高階濾波器;電流模式;品質因素補強電路;階梯型濾波器;電子工程;Analog Filters;High-Frequency Filters;High-Order Filters;Current-Mode;Q-Enhancement Circuits;Ladder Filters;ELECTRONIC-ENGINEERING
Issue Date: 1996
Abstract: ABSTRACT In this thesis, CMOS very high-
frequency(VHF)continuous-time current and voltage-mode lowpass
and bandpass biquadratic filters are proposed and analyzed.
Combined with the proposed Q-enhancement circuits, the high-Q
current-mode VHF biquadratic lowpass and bandpass filters can be
constructed and used as the building blocks for the
implementation of the current-mode continuous-time VHF bandpass
ladder filters. The performances of these proposed VHF filters
have been successfully designed and fabricated in 0.8 um CMOS
N-well DPDM technology and the experimental chips have
successfully been measured and verified the simulated
characteristic. Firstly, the linear wideband finite-gain current
and voltage-mode amplifiers constructed by tunable wideband
transresistance (Rm) amplifier and (Gm) amplifier are proposed
and applied to the design of VHF continuous-time current and
voltage-mode filters.Considering the intrinsic capacitances of
MOSFETS as filter elements, the Rm-Gm (Gm-Rm) finite-gain
current(voltage) amplifier configuration can be regarded as VHF
current (voltage)-mode biquadratic lowpass filter directly.The
proposed biquadratic lowpass filters have simple structures and
occupy small chip area and consume little power. Higher-order
VHF lowpass filters can be realized by cascading the biquads
directly. Moreover, a new Q-enhancement circuit which consists
of a wideband tunable positive-gain voltage amplifier and a
Miller capacitor is also proposed to enhance both maximum-gain
frequency fM and maximum-gain quality factor QM of the VHF
lowpass biquads. Experimental results successfully demonstrate
capability of the proposed new filter implementation methods in
realizing VHF current(voltage)-mode biquadratic lowpass filter
with maximum-gain frequency fM tunable in the range of 102 MHz
to 148 MHz (92 MHz to 142 MHz) whereas the maximum-gain quality
factor QM tunable from 1.13 to 1.49 (1.05 to 1.19). The measured
maximum signal level for voltage (current)-mode biquadratic
lowpass is 38.9 mVrms(92 uArms) and dynamic range is 50 dB (48.5
dB) with the power dissipation to be 20 mW (21.8 mW) under □2.5
V power supply system. Moreover, after applying the Q-
enhancement technique to the current-mode lowpass biquad,the
maximum-gain frequency fM can be increased up to 186 MHz and the
maximum-gain quality factor QM can be enhanced as high as 18.5.
The measured maximum signal level for the current lowpass biquad
with Q-enhance is 87.3 uArms and the dynamic range is 46 dB
with the power dissipation 221.4 mW under □2.5 V power supply
system. Secondly, based on the Rm-C biquadratic bandpass
structure and Q-enhancement technique,the VHF current-mode high-
Q bandpass biquadratic filter is constructed and applied as the
basic building block for the realization of VHF current-mode
bandpass ladder filter.Starting from the prototype of RLC
bandpass ladder filter and assigning proper state variables, the
state equations of the bandpass ladder filter can be
represented all by current-mode state variable with form of
high-Q current bandpass biquadratic function.Therefore,the
current-mode continuous-time bandpass ladder filter can be
implemented using current high-Q bandpass biquads as basic
cells. Experimental chip of the 6-order current bandpass ladder
filter has been designed and fabricated.Experimental results
successfully demonstrated the current-mode bandpass ladder
filter with center frequency f0 up to 48.4 MHz. The measured
maximum signal level for the current bandpass ladder filter is
29.6 uArms and the dynamic range is 48.3 dB. The chip area is
1.14 mm2 and the power dissipation is 73.3 mW/pole for □.5 V
power supply system. Moreover, combining the Rm-C and Rm-Gm
structures with Q-enhancement circuits, the VHF current-mode
continuous-time high-Q biquadratic section which performs
bandpass and lowpass filtering is proposed. Similarly,starting
from the prototype of RLC ladder filter with transmission zero
and assigning proper state variables, it is shown that state
equations of the current-mode bandpass ladder filter with
transmission zero can be represented all by current state
variables and rewritten in form of high-Q lowpass biquadratic,
high-Q bandpass biquadratic, and current differential functions.
Thus, the proposed current-mode bandpass ladder filter with
transmission zero can be implemented using current high-Q
bandpass biquads,high-Q lowpass biquads,and current-mode
differentiators as basic cells.The current-mode bandpass
ladder filter of f0 up to 50 MHz with a transmission zero f0z
as high as 70 MHz and the current bandpass ladder filter of f0
up to 50 MHz with a transmission zero f0z located at 35 MHz have
been successfully designed and simulated by HSPICE. From the
simulation , it is shown that the proposed filters have simple
structures, high center frequencies, and low component
sensitivities. Finally, for the design of low voltage low power
VHF continuous-time lowpass filters,simple-structur ed wideband
finite-gain voltage amplifiers are proposed. Both single-ended
and fully-balanced topologies have been developed.Experimental
results have successfully shown that the fM of the single-stage
(fully-balanced) Gm-Rm lowpass biquad can be as high as 237.4
MHz (237.4 MHz) with the maximum-gain quality factor QM to be
2.59(2.26) for 1.25 V power supply voltage. The power
consumption is 3.37 mW (9.44 mW), the maximum signal level is
12.3 mVrms (84 mVrms), and the dynamic range is 30 dB (48.5 dB).
The maximum-gain frequency fM of the fabricated VHF Gm-Rm
lowpass filters can be tuned in a range larger than 35 MHz.
Moreover, higher-order VHF lowpass filter can be implemented by
cascading biquads directly.Since intrinsic capacitor are
considered as filter elements and not any linear capacitor added
in the proposed filters,the filters are transistor-only and can
be implemented using standard digital VLSI process. The
simplicity in circuit structure result in small chip area and
low power consumptions.These beneficial characteristics make
the proposed VHF filters suitable for integrated mixed-mode
circuit design and low power applications. It is believed that
the proposed current and voltage-mode VHF continuous-time
filters and their design methodology offer new design scope and
feasibility for analog ICs. Further research will be conducted
in the future.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT854428002
http://hdl.handle.net/11536/62487
Appears in Collections:Thesis