Djekic, D.; Fantner, G.; Behrends, J.; Lips, K.; Ortmanns, M.; Anders, J.: A Transimpedance Amplifier Using a Widely Tunable PVT-Independent Pseudo-Resistor for High-Performance Current Sensing Applications. In: 2017 43rd IEEE European Solid State Circuits Conference (ESSCIRC), Leuven, BELGIUM, SEP 11-14, 2017 . IEEE, 2017. - ISBN 978-1-5090-5025-3, p. 79-82
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In this paper, we present a pseudo-resistor-based transimpedance amplifier (TIA) whose transimpedance value is PVT-independent and continuously tuneable over a wide range. The nonlinearity of the pseudo-resistors is mitigated by connecting a large number of elements in series and the effect of process variations on the pseudo-resistor is canceled by a biasing network based on a pseudo current mirror. The design is also first order temperature compensated exploiting the PTAT behavior of the proposed pseudo-resistor and using a PTAT current reference for its biasing. The proposed architecture is verified using a prototype manufactured in a 0:18 μm CMOS SOI technology. In this prototype, the transimpedance can be adjusted between approximately 1M and 1G . The achievable bandwidth varies inversely proportional with the transimpedance value from around 7 kHz for a value of 1G up to an opamp-limited maximum of 2MHz. In the white region, the input referred noise is equal to that of a TIA using an equivalent ohmic resistor. A minimum value of 5 fA= p Hz is achieved for a transimpedance of 1G . Over a temperature range from 􀀀40 C to 125 C, the transimpedance varies less than 10% for 1M . The TIA occupies a chip area of 0:07mm2. At room temperature, the power consumption is 9:5mW from a single 1:8V supply of which the pseudo-resistor consumes 0:2mW.