Precise RSSI with High Process Variation Tolerance

Abstract

Abstract-A receiving signal strength indicator (RSSI) built with transconductance amplifiers is presented. The RSSI achieves high tolerance to process variations by utilizing the unique nature of branch currents in a transconductance amplifier. These branch currents are used to implement a current-mode rectifier and amplitude clipping circuit that are tolerant of process variations. An on-chip offset control loop permits the entire RSSI to be realized with only one external component. In 0.18μm CMOS with a 1.8V supply, the RSSI draws 2.5mA and provides 80dB of offset suppression and more than 70dB of log-linear range with less than +/-2dB error due to process variation.

A fully integrated RSSI and an ultra-low power SAR ADC for 5.8 GHz DSRC ETC transceiver

“…An offset cancellation usually consists of an LPF and an offset subtractor. An external passive LPF is used in [4][5][6]. In [10][11], the use of AC-coupling prevents DC offset from propagating along the amplifier chain.…”

“…Moreover, since the OBU system is battery powered and attached to a vehicle window, it is desired to minimize power consumption and limit off-chip components to improve user convenience and system size. However, up to date, traditional RSSI circuits [3][4][5][6][7] [10] and [12] have difficulties to realize wide input ranges (e.g., 80dBm). These RSSIs also exhibit slow transient response, high power consumption, and low level of system integration due to the use of large off-chip capacitors.…”

Ultra-Low Power Transceiver Design

“…The successive-detection architecture [29] is used in the receiver to realize the logarithmic-linear form as shown Fig. 27.…”

A Fast RSSI using Novel Logarithmic Gain Amplifiers for Wireless Communication

“…Traditional RSSI circuits are generally realized in a logarithmic-linear form to cover several order of signal magnitude using successive-detection architecture. It requires an external large capacitor for a small signal ripple for low pass filtering, so that it makes slow settling time from the receiver power-on signal [2]. Besides, the rectifier and limiter used in conventional RSSI circuit typically have a range about 10 dB.…”