In this study, a fifth-order lowpass log-domain Butterworth filter, which is appropriate for Bluetooth/Wi-Fi receiver, is designed with signal flow graph approach. The filter is realized by using a unique translinear integrator circuit. Bluetooth and Wi-Fi modes are obtained without changing the circuit configuration. To change the mode of the filter, it is needed to change the cutoff frequency of the filter that can be electronically tuned by adjusting the external currents. Wi-Fi and Bluetooth receivers have 6MHz and 600kHz cutoff frequencies, respectively. Only BJTs and grounded capacitors were utilized to achieve the desired circuit. Lowpass log-domain Butterworth filter was simulated by using SPICE simulation program. A validated BJT and idealized BJT models are used to obtain simulation results confirming the theoretical analysis.
['Tuba Nur Gul', 'Ali Kircay']
The Design of Fifth-Order Butterworth Lowpass Log-Domain Filter for Bluetooth/Wi-Fi Receiver Using Signal Flow Graph Method