Wideband Variable Gain Control Amplifier for 60 GHz Receiver
Yanjie Wang and Ali Niknejad
Recent advances in nanometer CMOS technology have made it possible to build low-cost radio transmitter/receiver systems operating around 60 GHz mm-wave frequencies. The wideband variable gain control amplifier (VGA) is an essential building block to maximize the dynamic range of receiver systems and adjust the received signal amplitude. To be practical for high-volume, low-cost applications, the chipset should achieve as high an integration level as possible and avoid using on-chip inductors. A VGA with wide bandwidth, large gain tuning range, small chip area, and low power consumption is highly desired. The goal of this project is to integrate the whole front end receiver (LNA, mixer, VGA) in a single-chip die. A novel wideband (0~2 GHz) inductor-less differential VGA with DC-offset cancellation network has been proposed for low power consumption and small chip size. A test chip has been fabricated in 90 nm digital CMOS technology and measured using on-chip probes. The functionality of the VGA has been verified. The high-speed oscilloscope plot clearly shows 2 GHz differential signals measured at the output.
Figure 1: Die micrograph of the VGA
Figure 2: Measured transient response of the VGA differential outputs with -38 dBm, 2 GHz input testing signal