Test signal generation for the calibration of analog front-end circuits in biopotential measurement applications

A test signal generator to calibrate analog front-ends for biopotential measurements is presented. The integrated signal generator enables detection of the input impedance at the front-end instrumentation amplifier based on current injection and amplitude detection. It can generate picoampere currents while ensuring a high output impedance of 2.9GΩ up to 100Hz. The test signal generator was designed and simulated in 0.13μm CMOS technology and it consists of a temperature-compensated relaxation oscillator, a frequency divider, a limiter, and an operational transconductance amplifier.