Received Signal Strength Indicator Circuit for Wireless Communication Systems

To solve the problems that accuracy of traditional signal strength indicator circuit is low and resistance to temperature and process variations is not enough strong, a system model for RSSI (received signal strength indicator) circuit was set up. The relationship between limiting amplifier gain and signal strength detection unit error was derived, and measures to decrease the error were obtained. Through analyses ways to reduce gain change with temperature and process under the condition of improving accuracy were gained. Based on the analyses, a gain-enhanced structure was introduced to improve the accuracy of limiting amplifier gain and raise its ability to resist temperature and process variations. The designed circuit uses 0.18 μm bulk silicon (CMOS) technology with 1.8 V power supply, and its area is 500 μm × 200 μm. The test results show that the dynamic gain range of the circuit can reach 55 dB while test temperature changes from -40 ℃ to 85 ℃. The circuit can provide a bandwidth greater than 55 MHz and its detection error is less than 1.5 dB. The power consumption of the circuit is 1.89 mW, and its detection accuracy is up to 1.5 dB.