A Wide Bandwidth Current Mode Filter Technique Using High Power Efficiency Current Amplifiers with Complementary Input


IEICE TRANSACTIONS on Electronics   Vol.E100-C    No.6    pp.539-547
Publication Date: 2017/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E100.C.539
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Their Application Technologies)
current amplifier,  CMOS,  complementary input,  wide bandwidth,  low pass filter,  

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60GHz wireless communication requires analog baseband circuits having a bandwidth of about 1GHz. This paper presents a wide bandwidth current-mode low pass filter technique which involves current amplifiers, resistors and capacitors. The proposed current-mode filter is obtained by replacing an integrator employing an op-amp with another integrator employing a current amplifier. With the low input impedance current amplifier having little variation of the input impedance, the proposed filter is expected to improve linearity and power efficiency. The proposed current amplifier which employs super source follower topology with complementary input is suitable for the filter because of its class AB operation. Although simulation results shows the conventional current amplifier which employs super source follower topology without the complementary input has 12Ω variation and 30Ω input impedance, the proposed current amplifier has 1Ω variation and 21Ω input impedance. A fourth order 1GHz bandwidth filter which involves the proposed current amplifiers is designed in a 65nm CMOS technology. The filter can achieve IIP3 of 1.3dBV and noise of 0.6mVrms with power consumption of 13mW under supply voltage of 1.2V according to simulation results with layout parasitic extraction models. Active area of the filter is 380μm×170μm.