Implementation of Tunable Gm-C High-pass Filter using Linearized Transconductor

Objective: Now a day there is an increase demand for higher linear circuits in a wireless communication system. The linear circuit provides better support for wireless communication. To process the signals and remove unwanted block or interferers, the transmitting end and receiving end must consist of highly linearity circuit. Methods/Statistical Analysis: A tunable G_m-C high-pass filter implemented using linearized transconductor circuitry, is proposed in this paper. By employing a dual path feed forward technique, the transconductor circuitry cancels the term G_m3 thus acting a good linear Voltage-to-Current conversion. This design consists of a voltage buffer which uses only inverters, which can drive transconductor with differential inputs. A higher order admittance method is utilized to synthesize the filter. The high pass filter is implemented in 180nm UMC CMOS technology. Findings: A linearization transconductor circuit system is proposed. Using voltage buffer which incorporates inverters and copied unique transconductors, better linearization is achieved. A wider tuning range of the filter cutoff frequency varying from 0.17 MHz to 0.85 MHz is obtained. A low current consumption of 10 mA to 30 mA over the tuning range is observed. Further, the harmonic distortion analysis revealed that the input-referred third-order intercept point (IIP3) is +25.84 dBm with a 1-dB compression point being +9.35 dBm. A filter linearity of less than one percent (<1%) shows that the proposed design has better linearity. Application/Improvements: The simulation results validates that the filter design is highly linear, thus an efficient line arization technique is proposed. Further, this design methodology can be adapted for transconductors having varied differential inputs, and also provides design feasibility for multiple processes.