关键词: 短距无线通信, 2.4 GHz射频, 低功耗, 滤波器

Abstract: A baseband filter for 2.4 GHz low-power communication systems was designed based on 22 nm CMOS technology. The filter employs a cascaded structure combining a second-order multiple feedback (MFB) filter and a first-order variable gain filter to achieve third-order filtering, simultaneously meeting the wide gain adjustment requirements of RF receiver chains.To implement the negative feedback structure of the filter,a fully differential operational amplifier circuit with high GBW was designed to satisfy the high gain-bandwidth and linearity requirements of the filter. To prevent process variations that may cause RC time constant deviations and filter performance parameters drift, an RC calibration circuit was designed to calibrate the filter bandwidth. In traditional RF systems, three operational amplifiers are typically required to implement a third-order low-pass filter (LPF) and a variable gain amplifier (VGA). This paper innovatively integrates the functions of the two modules, using only two operational amplifiers to realize both functions. This reduces the number of operational amplifiers used, thereby saving chip area and lowering power consumption. Test results demonstrate that the filter achieves a 20 MHz bandwidth with a gain range of -3 dB to 24 dB, while exhibiting excellent temperature stability.

Key words: WLAN, 2.4 GHz RF, low-power, filter