Low power receiver with merged N-path LNA and mixer for MICS applications

Abstract

In this paper, a low power receiver for medical implant communication service (MICS) is presented. Low power design is vital in the MICS applications since the implanted chip has to work for a long time without the need to change its battery. As a result, a merged N-path low noise amplifier (LNA) and mixer block is proposed. In this structure, the LNA and down-conversion mixer share a transconductance to lower the overall power consumption. An N-path feedback is utilized around the shared transconductance not only to improve the LNA selectivity and relax the linearity requirements but also to downconvert the radio frequency (RF) component and create the intermediate frequency (IF) signal. In other words, the shared transconductance amplifies both RF and IF signals. First, the transconductance is used for amplifying the RF signal and then the IF signal. The complete receiver chain including merged N-path LNA and mixer, complex filter, IF amplifier, and frequency shift keying (FSK) demodulator are designed and simulated using standard 180 nm CMOS technology with a low supply voltage of 0.8 V and low power consumption of only 162.5 µW. The NF of the receiver is 9.2 dB at 1.5 MHz offset frequency.