Current conveyor based amplifier and adaptive buffer for use in an analog frontend

We present an instrumentation amplifier based on second generation current conveyors (CCII+). The design is implemented in a 0.6 ¿m CMOS technology, incorporating several circuit techniques necessary for achieving high resolution at very low input signal levels. Compared to simulated results reported in recent literature, we show that in an actual silicon implementation, several detrimental circuit effects have to be countered. A conventional instrumentation amplifier and a buffer is used as second stage to match the high impedance output of the current conveyors to the low impedance input of an SC ADC. The buffer amplifier is composed of a conventional class A OTA, retrofitted with a positive feedback adaptive bias current supply, which offers class AB power and slew rate performance at class A linearity. Measurement results are given, showing the veracity of the approach.