A Gain Boosted Folded Cascode using Telescopic Boosting Amplifiers with Switched Capacitor Input Level Shifters

Abstract

This paper describes a single stage fully differential folded cascode operational transconductance amplifier (OTA) with fully differential gain boosting amplifiers designed in 1.2 VDC 130nm CMOS process technology. The amplifier is the driver for the analog to digital converter (ADC) of a blood pressure sensing medical implant [1] which uses wireless power transmission as its energy source [2]. The medical implant's design specifications require an amplifier with wide output swing, high accuracy, and the bandwidth to drive a differential 5 pF load at 4 ksps with minimum power consumption. The gain boosting amplifiers are telescopic cascoded amplifiers, which, by their design, have an input and output common mode voltage relationship which is opposite to what is needed for a gain boosted cascode configuration. To correct for this, a method for DC shifting the amplifier's input voltage using a switched capacitor network is presented.

The Design of a Fully Differential Capacitive Pressure Sensor with Unbalanced Parasitic Input Capacitances in 130nm CMOS Technology

“…Three different designs have been created with the Cadence Design Framework using the UMC 130nm technology, and the design variables are listed in Table 2. The amplifier architecture which is used for each design is the gain boosted folded cascode amplifier from Figure 10 (Bradford et al, 2013) which is able to provide 102 dB of gain over the required ±850 mV of output swing. Eq.…”