A 1.2v Improved Operational Amplifier for Bio- Medical Applications

In recent years, there is an ever-growing demand for low-power and low-noise mixed signal integrated circuits for applications such as portable medical systems. A high level of system integration is required to implement bio-potential system with mixed signal circuits. The most commonly observed bio-potentials used for medical diagnoses are monitored non-invasively with electrodes placed on the surface of the skin (Lee et al 2006). These include the electrocardiogram or ECG which monitors heart activity; the electromyogram (EMG) which monitors muscle activity in the body; and the electroencephalogram (EEG) which monitors electrical activity in the brain. Generally, the integrated chip offers a relatively low-cost product for both ECG and EEG signals, but with high power consumption. To overcome this problem, programmable components with adjustable trade-off between noise and power dissipation are embedded in the same chip. The main source of noise is found in the first component, i.e. the preamplifier when recording the biomedical signals. Hence, a programmable operational amplifier (popamp) that acts as a preamplifier is the key component (Van Helleputte et al 2008) in the design of bio-medical system.