A 1.2 V rail-to-rail analog CMOS rank-order filter with k-WTA capability

In this paper, we design a rank-order filter with k-WTA capability for 1.2 V supply voltage. The circuit can find a rank order among a set of input voltages by setting different binary signals. Moreover, without modifying the circuit, the k-WTA function can be easily configured. The circuit has been designed using a 0.5 μm DPDM CMOS technology. Seven input voltages are used to verify the performance of the circuit. The results of HSPICE post-layout simulation show that the response time of the circuit is 10 μs for each rank-order operation, the input dynamic range is rail-to-rail, and the resolution is 10 mV for 1.2 V supply voltage. An experimental chip has been fabricated, in which accuracy of the comparator is measured as 40 mV for low-voltage operation. The dynamic power dissipation of the chip is 550 μW.