Low-voltage analog circuit design based on biased inverting opampconfiguration

摘要

Analog circuit designs that use inverting opamp configuration cannbe converted into low-voltage designs by biasing the opamp inputncommon-mode voltage to near one of the supply rails. This is achieved bynintroducing a current source or a resistor between the opamp negativeninput terminal and one of the supply rails. Hence, in this technique,nopamps with limited input common-mode range can be used. In addition,nswitches can be incorporated in these circuits to allow a wide range ofnapplications. This technique also allows large input and output signalnswings (close to rail-to-rail), even at a very low-voltage supply. Tondemonstrate the proposed technique, four track-and-hold amplifiersn(THA's) and a 10 bit digital-to-analog converter (DAC) have beenndesigned in a conventional 1.2 Μm CMOS process and tested at a 1 Vnsupply. The DAC consumes less than 0.45 mW and has a maximum throughputnof 1 MS/s, with close to rail-to-rail output (0.1-0.9 V). The maximumndifferential nonlinearity error and integral nonlinearity error werenmeasured to be 1.7 least significant bits (LSB's) and 3.0 LSB's,nrespectively. Each THA dissipates less than 0.35 mW and achieves a holdnmode total harmonic distortion of less than -61 dB for a 100 kHz, 1.4 Vnp-p differential input signal, sampled at a rate of 1 MS/s