TY - JOUR
T1 - Explicit design formulas for current-mode leap-frog OTA-C filters and 300 MHz CMOS seventh-order linear phase filter
AU - Sun, Y.
AU - Zhu, X.
AU - Moritz, J.
N1 - The defnitive article can be found at: http://www3.interscience.wiley.com/ Copyright Wiley. [Full text of this article is not available in the UHRA]
PY - 2010
Y1 - 2010
N2 - The leap-frog (LF) configuration is an important structure in analogue filter design. Voltage-mode LF OTA-C filters have recently been studied in the literature; however, general explicit formulas do not exist for current-mode LF OTA-C filters and there is also need for current-mode LF-based OTA-C structures for realization of arbitrary transmission zeros. Three current-mode OTA-C structures are presented, including the basic LF structure and LF filters with an input distributor or an output summer. They can realize all-pole characteristics and functions with arbitrary transmission zeros. Explicit design formulas are derived directly from these structures for the synthesis of, respectively, all-pole and arbitrary zero filter characteristics of up to the sixth order. The filter structures are regular and the design formulas are straightforward to use. As an illustrative example, a 300 MHz seventh-order linear phase low-pass filter with zeros is presented. The filter is implemented using a fully differential linear operational transconductance amplifier (OTA) based on a source degeneration topology. Simulations in a standard TSMC 0.18µm CMOS process with 2.5 V power supply have shown that the cutoff frequency of the filter ranges from 260 to 320 MHz, group delay ripple is about 4.5% over the whole tuning range, noise of the filter is 420nA/Hz, dynamic range is 66 dB and power consumption is 200 mW.
AB - The leap-frog (LF) configuration is an important structure in analogue filter design. Voltage-mode LF OTA-C filters have recently been studied in the literature; however, general explicit formulas do not exist for current-mode LF OTA-C filters and there is also need for current-mode LF-based OTA-C structures for realization of arbitrary transmission zeros. Three current-mode OTA-C structures are presented, including the basic LF structure and LF filters with an input distributor or an output summer. They can realize all-pole characteristics and functions with arbitrary transmission zeros. Explicit design formulas are derived directly from these structures for the synthesis of, respectively, all-pole and arbitrary zero filter characteristics of up to the sixth order. The filter structures are regular and the design formulas are straightforward to use. As an illustrative example, a 300 MHz seventh-order linear phase low-pass filter with zeros is presented. The filter is implemented using a fully differential linear operational transconductance amplifier (OTA) based on a source degeneration topology. Simulations in a standard TSMC 0.18µm CMOS process with 2.5 V power supply have shown that the cutoff frequency of the filter ranges from 260 to 320 MHz, group delay ripple is about 4.5% over the whole tuning range, noise of the filter is 420nA/Hz, dynamic range is 66 dB and power consumption is 200 mW.
U2 - 10.1002/cta.563
DO - 10.1002/cta.563
M3 - Article
SN - 0098-9886
VL - 38
SP - 367
EP - 382
JO - International Journal of Circuit Theory and Applications
JF - International Journal of Circuit Theory and Applications
IS - 4
ER -