A 5-Gb/s Automatic Gain Control Amplifier With Temperature Compensation

This paper presents an automatic gain control (AGC) amplifier with temperature compensation for high-speed applications. The proposed AGC consists of a folded Gilbert variable gain amplifier (VGA), a dc offset canceller, inductorless post amplifiers, a linear open-loop peak detector (PD), an integrator, a symmetrical exponential voltage generator, and a compensation block for temperature stability. The novel temperature compensation scheme ensures the AGC stability and accuracy over -20°C-200°C by predicting the integrator biasing voltage based on the crucial blocks duplication technique. The proposed linear open loop PD combined with the linear-in-dB VGA manages the dB-linear error of less than 0.3 dB for the received signal strength indication (RSSI). The AGC chip is fabricated using a 0.13-μm SiGe BiCMOS technology. Consuming a power of 72 mW from a 1.2-V supply voltage, the fabricated circuit exhibits a voltage gain of 40 dB and a 3-dB bandwidth of 7.5 GHz. With a 2¹⁵ - 1 pseudo-random bit sequence at 5-Gb/s, the measured peak-to-peak jitter is less than 40ps_pp across the -20°C-200°C temperature range. The low linear-in-dB error and the wide operating temperature range achieving the high-speed data input signal indicate the suitability of the proposed techniques for high-speed AGC amplifiers.