Voltage-mode first-order universal filter realizations based on subtractors

Two new voltage-mode (VM) first-order universal filters including two subtractors as active elements as well as one resistor and one capacitor (grounded) as passive components are proposed in this paper. Each of the proposed first-order universal filters can realize low-pass response, high-pass response with a low output impedance and all-pass response with a low output impedance simultaneously. As a result, each of them can be connected to any other VM structures easily. Neither of them suffers from passive element matching conditions. They are free from non-ideal current gains which are frequency dependent. Nevertheless, each of them does not have the feature of high input impedance. A lot of simulations where 0.13 µm IBM CMOS technology parameters are used are carried out through SPICE program. The power supply voltages of the subtractors are chosen as ±0.75 V. Each of the proposed first-order universal filters dissipates 1.77 mW. Furthermore, an experimental test is accomplished so as to show the performance of the first proposed first-order universal filter as an example.