Fully differential DDA-based fifth and seventh order Bessel low pass filters and buffers for DCR radio systems
In this letter the design, fabrication and measurements of fully differential filters and buffers in a 180 nm CMOS process for direct conversion receivers (DCRs) applications are reported. The fully differential fifth and seventh order Bessel low pass filters and buffers are completely based on a differential difference amplifier with common mode feedback capability. In particular, the filters have been designed with a tunable 100 kHz-1 MHz 6 dB bandwidth, in two steps, in order to allow the DCR radio to operate with a 100 Kbit/s-1 Mbit/s data rate. The circuits operate at a 3.3 V supply voltage. The whole chip power consumption, implementing four buffers, two-fifth and two-seventh order low pass filters, is only 6 mW, being particularly suitable for portable apparatus.
fully differential differential difference amplifier active filter