A four-channel bi-directional CMOS core chip for X-band phased array T/R modules

This paper presents a four-channel bi-directional core chip in 0.13 um CMOS for X-band phased array Transmit/Receive (T/R) module. Each channel consists of a 5-bit step attenuator, a 6-bit phase shifter, bi-directional gain blocks (BDGB), and a bi-directional amplifier (BDA). Additional circuits such as low drop out (LDO) regulator, bias circuits with band-gap reference (BGR), and serial to parallel interface (SPI) are integrated for stable biasing and ease of interface. The chip size is 6.9 × 1.6 mm² including pads which corresponds to 2.8 mm² per channel. The phase and attenuation coverage is 360° with the LSB of 5.625°, and 31dB with the LSB of 1dB, respectively. The RMS phase error is better than 2.3°, and the RMS attenuation error is better than 0.25 dB at 9-10 GHz. The Tx mode reference-state gain in each channel is 11.3-12.2 dB including the 4-way power combiner insertion losses ideally 6 dB, and the Rx mode gain is 8.6-9.5 dB at 9-10 GHz. The output P1dB in Tx mode is > 11 dBm at 9-10 GHz. To the best of authors´ knowledge, this is the smallest size per channel X-band core chip in CMOS technology with bi-directional operation and competitive RF performance to-date.