# A Low-Band Multi-Gain LNA Design for Diversity Receive Module with 1.2 dB NF
###### Abstract  
This paper presents and discusses a Low-Band (LB) Low Noise Amplifier (LNA) design for a diversity receive module where the application is for multi-mode cellular handsets. The LB LNA covers the frequency range between 617 MHz to 960 MHz in 5 different frequency bands and a 5 Pole Single Throw (SPST) switch selects the different frequency bands where two of them are for the main and three for the auxiliary bands. The presented structure covers the gain modes from \(-12\) to 18 dB with 6 dB gain steps where each gain mode has a different current consumption. In order to achieve the Noise Figure (NF) specifications in high gain modes, we have adopted a cascode Common-Source (CS) with inductive source degeneration structure for this design. To achieve the S\({}_{11}\) parameters and current consumption specifications, the core and cascode transistors for high gain modes (18 dB, 12 dB, and 6 dB) and low gain modes (0 dB, \(-6\) dB, and \(-12\) dB) have been separated. Nevertheless, to keep the area low and keep the phase discontinuity within \(\pm 10^{\circ}\), we have shared the degeneration and load inductors between two cores. To compensate the performance for Process, Voltage, and Temperature (PVT) variations, the structure applies a Low Drop-Out (LDO) regulator and a corner case voltage compensator. The design has been proceeded in a 65-nm RSB process design kit and the supply voltage is 1 V. For 18 dB and \(-12\) dB gain modes as two examples, the NF, current consumption, and Input Third Order Intercept Point (IIP3) values are 1.2 dB and 16 dB, 10.8 mA and 1.2 mA, and \(-6\) dBm and 8 dBm, respectively.  
c 2021 21 The focus of this paper is to implement the LB Low-Noise Amplifier (LNA) part where the frequency range is 617-960 MHz. This frequency range has been covered in five bands where B8 (925-960 MHz) and B26 (859-894 MHz) are the main bands of this design and are selected with two of the switches in 5 Pole Single Throw (5 PST). Three auxiliary bands that are selected with the remaining three switches of the 5 PST, cover the whole frequency range again including B8, B26 in one band, B71 & B29 (617-652 MHz) & (717-728 MHz) in the other band, and B12, B28, B20 (729-746 MHz & 758-803 MHz & 791-821 MHz) in the third band for later uses. This structure covers the gains from \(-\)12 to 18 dB in 6 modes with 6 dB gain steps and with different current consumption. Phase of different gain modes (positive and negative) is usually set inside the modem. However, in this work to achieve \(\pm\)10\({}^{\circ}\) phase discontinuity in CMOS level, instead of a bypass mode for zero and minus gains, we have applied the second path of Common Source (CS) with degeneration. Nevertheless, to keep the area small, the degeneration and load inductors have been shared between these paths.  
To achieve the power consumption specifications, the bias voltages of the LNA is controlled. Additionally, to get the Process, Voltage, and Temperature (PVT) independency, a bias voltage compensator together with a Low Drop-Out (LDO) regulator have been applied in the design.  
The structure of the paper is as follows: Section 2 discusses the structure of the LNA. In Section 3, the structure of the voltage generator is presented. Section 4 summarizes the experimental results and finally, Section 5 concludes the paper.  
Figure 1: Block diagram of the diversity RF front-end for 2G/3G/4G/5G multi-mode cellular handsets.