A novel temperature compensating method of Logarithmic Amplifier in RSSI

In this paper, we will present a new temperature compensating scheme dedicated to building CMOS Logarithmic Amplifier, which is suitable to low power applications. We propose a master-slave configuration to interrelate the PTAT (proportional to absolute temperature) coefficient of the Logarithmic Amplifier with the PTAT current, which can be obtained from the Band-gap Voltage Reference. With this method, a Low-Temperature-Coefficient Logarithmic Amplifier is obtained without any external components. This approach has been verified via Cadence simulation in TSMC 0.13μm CMOS process. A RSSI with such a logarithmic amplifier consumes only 145μW under the supply of 1.2V. This method and the complete circuit are presented in detail with the associated results.