Low-Power CMOS Complex Bandpass Filter with Passband Flatness Tunability

• DOI: 10.3390/electronics9030494
• Publication Date: 2020-03-17T13:27:41Z
• Authors: Jungah Kim; Yongho Lee; Shinil Chang; Hyunchol Shin
• Keywords: Passband; Digital biquad filter; Center frequency; Flatness (cosmology); Q factor

We present a low-power CMOS active-resistance-capacitance (active-RC) complex bandpass filter (BPF) with tunable gain, bandwidth, center frequency, quality factor, and passband flatness for Bluetooth applications. A transfer function analysis cross-coupled Tow-Thomas biquad structure is presented to prove that the profile of gain can be effectively controlled by independently tuning two cross-coupling resistors. The proposed biquad-based BPF was employed realize fourth-order baseband analog processor low intermediate frequency (low-IF) RF receiver. composed filters three first-order variable-gain amplifiers. It fabricated in 65-nm achieved wide capabilities, such as −15.6 50.6 dB, bandwidth 1.4–3.9 MHz, 1.5–4.1 −1 1 dB. also an image rejection ratio 40.3–53.3 dB across entire range. consumed 1.4 mA from V supply occupied area 0.19 mm2 on silicon substrate. implementation results able enhance signal processing performances through flexible wide-range tunability flatness, well factor.