E-band transceiver monolithic microwave integrated circuit in a waveguide package for millimeter-wave radio channel emulation applications

In the development of 5G prototype systems and terminal demonstration platforms, a wireless channel emulator plays a crucial role in the test and verification process. With online and real-time simulation characteristics such as path loss, shadowing and multi-path fading of transmitted signals from antenna ports in a wireless environment, a wireless channel emulator can accurately measure the effects of wireless environments on system performance. This is a high-end universal instrument for verifying the performance of system devices and terminals in various complex scenarios. As 5G new radio applications develop rapidly, radio channel emulators that cover the millimeterwave (mmWave) range are required, which have been rarely reported thus far. In the global market, Keysight first released its advanced PROPSIM channel emulator products along with multi-band transceivers, which support a frequency of up to 43.5 GHz [1]. However, in the 66–71 GHz band, which is one of the 5G mmWave spectrums approved at the World Radiocommunication Conference 2019 [2], similar high-performance emulators have not been reported publicly. As massive multiple-input multiple-output (MIMO) technology and the corresponding theory have matured, the number of antennas in 5G systems has increased. Therefore, systematic conductive testing has become increasingly impractical because of long calibration times, confined spaces, high cost and exponentially increasing complexity in the mmWave band. By contrast, over-the-air (OTA) testing with multiple probes in a shielded anechoic chamber has become the main solution [3,4]. The channel emulator plays an essential role in a typical 5G mmWave massive MIMO OTA measurement setup. In the E-band (60–90 GHz), however, dozens of conventional coaxial connectors are required, which are bulky, costly, and very lossy. Therefore, a lowcost, compact, and low-loss solution is a key consideration in designing E-band transceivers for channel emulators. Moreover, the dynamic power range should be high enough to simulate various channel characteristics. In this study, we present a mmWave transceiver monolithic microwave integrated circuit (MMIC) in a waveguide package. Highly selective band-pass and high-pass on-chip filters and multiple harmonic suppression techniques are employed to realize a compact transceiver module with a high dynamic output power range of up to 50 dB over a frequency range of 66–76 GHz. To the best of our knowledge, the proposed integrated module is the first demonstration of an E-band transceiver system for mmWave radio channel emulation applications. Transceiver architecture. The transceiver MMIC is realized by cascading a few function blocks including a tripler, a first band-pass filter (BPF), an amplifier, a high-pass filter (HPF), a mixer and a second band-pass filter, as shown in Figure 1(a). A tripler, rather than a doubler or higherorder multiplier is chosen here to realize the trade-off between the local oscillator (LO) source cost and gain budget. The tripler, power amplifier (PA) and mixer are all nonlinear components, which means that various idle harmonic signals are generated. To obtain a high operational power range, all nearand in-band combination signal powers need to be kept sufficiently lower than the minimum useful signal power. Therefore, we choose an appropriate intermediate frequency (IF) to push the potential high-power harmonics out of the band of interest. Under normal conditions of LO, the fourth harmonic has a relatively higher power than the fifth one. For the 66–76 GHz band, the fourth harmonic of the LO frequency could be pushed out when the IF is chosen as 27 GHz. Out-of-band spurious signals could be effectively suppressed by low-cost and highly selective offchip filters. Furthermore, new fourth and fifth harmonics could be converted from relatively higher-power, low-order harmonics because of mixer nonlinearity. An HPF is there-