Current Mode Design Logarithmic Domain Filter

Current mode Log-domain filter circuit applies the companding analog processingtechnology, and use the index V-I characteristic of active components, such as BJT,Log-domain filters are able to work in the case of low power supply voltage and highfrequency, which could keep the larger dynamic range and tuning range. Thereforelog-domain filter in the high frequency signal processing field has wide applicationprospect.This topic is based on CSMC0.18μm process, using Cadence simulation software,the analogy method of log-domain filter is used with RLC ladder network, that is to say,we use Log-domain integrator to replace RLC integrator in passive network, this paperhas designed three order chebyshev low-pass log-domain filter and five order chebyshevlow-pass log-domain filter. The system is debugged and simulated under the conditionof1.8V power supply voltage, and the filter is simulated and analyzed atamplitude-frequency response, noise Characteristics and distortion characteristic. Weachieve that When the bias current is20μA, bandwidth tuning range of five orderlog-domain filter is0.5kHz to9.9MHz, stopband attenuation is63dB, the filter cutofffrequency can be regulated in a relatively wide range, so the filter circuit has goodamplitude frequency characteristics. Finally, for the landscape design, landscape area of52261.9μm2, and adopted the DRC and LVS verification.