ABSTRACT
The system performance of high-frequency continuous-time operational transconductance amplifier (OTA)-C filters depends on both the constituent components and the circuit architecture. This chapter introduces a general multiple integrator loop feedback approach for OTA-C filter design. It describes OTA-C filters based on voltage integrators and voltage feedback. The chapter provides a general theory and a systematic scheme for generating all-pole filter structures with concentration on minimum component OTA-C realizations and the enumeration of canonical filter structures. Universal OTA-C biquads can be derived based on the output summation and input distribution methods. The chapter analyzes the effects of OTA nonidealities, which embrace finite impedances, phase shift, and nonlinearity. The OTA impedances and excess phase cause a shift of filter frequency characteristics from ideal ones. In particular they change the pole positions and hence pose a potential risk of instability, while OTA nonlinearity and noise limit the filter dynamic range.
