Design of a Single-Ended to Differential Low-Noise Amplifier Based on Current Extraction Technology
Xingchen He, Xiaofeng Yang, Zhuo Chen · 2025
The wireless signal reaches the first stage of the receiver, the low-noise amplifier, via the receiving antenna. A balun is typically inserted between the antenna and the low-noise amplifier to convert the signal from single-ended to differential. However, introducing the balun increases noise and reduces integration, necessitating its integration into the chip. In addition to conventional considerations such as frequency range, gain, noise figure, and input matching, this low-noise amplifier requires attention to gain and phase mismatch between the two differential signals.This paper presents a balun-LNA designed using a 130nanometer CMOS process. The circuit consists of a balun-LNA core circuit and an output buffer stage. The Balun-LNA core circuit uses a classic common-source/common-gate structure. Current extraction technology is employed in the circuit to achieve a noise figure of less than 4 dB and balanced loading. To reduce power consumption, a negative feedback structure enhances the transconductance of the common-gate transistor. The output buffer, the second-stage circuit, uses a source follower to match the output impedance. Implementing this Balun-LNA using 130 nm CMOS technology achieves a noise figure of $\mathbf{2. 7 - 2. 8 ~ d B}$, a voltage gain greater than 12 dB, a gain mismatch of less than 1 dB, a phase mismatch of less than 2°, and an S11 of less than - 10 dB within the 800 MHz to 1.5 GHz frequency range.