Patent ID: 6400295
Filing Date: 2002-06-04
Classification: H03M

Abstract:
Transducer interface arrangement including sensor means (SM) for measuring a parameter, an Analog-to-Digital Converter (ADCb) and a selectable resistor string (SRSa),said sensor means having transducer input terminals (Vexc, Vss) to which an excitation voltage is applied and sensor output terminals (CPin, CNin) coupled to data input terminals (Pin, Nin) of said converter, said selectable resistor string (SRSa) having an input connected to said transducer input terminals and being adapted to produce an offset voltage derived from said excitation voltage by means of controlled switches included in said selectable resistor string, said offset voltage being applied to said converter, said analog-to-digital converter comprising a Sigma-Delta Modulator (SDMa, SDMb) including, connected to said data input terminals, the cascade connection of a first switched-capacitor module (SC1, SC1b), a first differential amplifier (A1), a second switched-capacitor module (SC2) and a second differential amplifier (A2), and further including a third switched-capacitor module (SC3) with an input (Pref, Nref) at which a reference voltage is applied and with an output connected to an input (PA1, NA1) of said first differential amplifier (A1) as well as a fourth switched-capacitor module (SC4) with an input (Pref, Nref) at which said reference voltage is applied and with an output connected to an input (PA2, NA2) of said second differential amplifier (A2), characterized in that said selectable resistor string (SRSa) is further adapted to produce said reference voltage applied to the inputs of said third (SC3) and fourth (SC4) switched-capacitor modules, and in that said sigma-delta modulator (SDMa, SDMb) further includes a fifth switched-capacitor module (SC5) to an input (Poff, Noff) of which said offset voltage is applied and with an output connected to the input terminals (PA1, NA1) of said first differential amplifier (A1).