A low-sensitivity programmable BJT current-mode filtering technique

A low-sensitivity temperature-compensated programmable BJT current-mode low-voltage filtering technique is proposed. We introduce a new technique in which the DC gain and the location of the second pole of the integrator are controlled such that the Q-enhancement, due to the second pole, is cancelled by the effect of finite DC gain. The technique is suitable for integration and can work with low-value capacitors. By making the filter time constant exactly proportional to r/sub e/C, good linear tunability is achieved over many decades. The programming current is varied as proportional to absolute temperature (PTAT) to stabilize the time constant r/sub e/C.