Active floating gate circuits

This paper presents a flexible biasing-method for floating gate circuits. The biasing technique preserves the floating gate nature of the well known floating gate modules at the same time as it provides an effective way to adjust the gate bias level continuously. Accurate adjustment of the gate voltage is essential to handle process and temperature variation. The method also makes it very easy to quickly tune the floating gate modules dynamically. The bias technique is based on the use of controllable current sources. A delay cell based on a pseudo floating-gate all-pass-filter intended used in a low-power delay line for medical real-time 3D ultrasound imaging system has been design for proof of concept. The biasing method is believed to take analog floating-gate circuits one step closer to commercial acceptance.